Previous Years

Summer Semester 2019

15.04.2019

Special EES seminar organised by Alexander Hutfluss and Niels Dingemanse with two speakers at 16:00 and 16:30

Hans Slabbekoorn - Anthropogenic noise impact on animals: concepts and conflicts

University Leiden, The Netherlands

Eira Bermudez Cuamatzin - Song, noise, and personality: a comparison between great tits and house finches

University Leiden, The Netherlands

06.05.2019

Maude Baldwin - Evolution of avian taste perception: sensory and physiological consequences of diet shifts

Max Planck Institute for Ornithology, Seewiesen, Germany

Abstract: Birds occupy a wide range of dietary niches- some species are generalists, others are specialists on fruit, nectar, seeds, or meat. Diet shifts across the bird phylogeny are accompanied by changes in many sensory and physiological systems. While differences in taste preferences as well as digestive enzyme activities have been explored in a variety of species using different assays, a clear mechanistic basis for the existing variation in both phenotypes is lacking for many birds. Physiological responses can also interact with sensory information and mask or alter apparent preference, so uncoupling the role of post-ingestive feedback from taste preferences can be challenging. Brief-access behavioral trials together with proteomics and functional assays in cell culture can help tease apart the sensory and metabolic mechanisms influencing food preference and diet selection. We present results from our ongoing work on taste receptors and digestive enzymes from birds with diverse diets to begin to understand the molecular underpinnings of diet choice, and to investigate the coevolution between the gustatory and digestive systems in birds.

13.05.2019

Tomer J. Czaczkes - Information use and value perception in social insects

University of Regensburg, Germany

Abstract: Social insects, such as ants and honeybees, have access to a wide array of information sources. These include private information (e.g. memories), and importantly social information from nestmates (e.g. pheromone trails). Oddly, social information is often ignored when private information is available. We find that this is likely due to social information lacking certainty along critical information dimensions. For example, pheromone trails are ambiguous about the quality of the food source they advertise. Supplementing social information along the lacking informational dimension can cause animals to begin relying on this type of information again, potentially explaining the frequent contacts of ants on trails. All this information integration is ultimately aimed at choosing the most valuable course of action. Animals are often considered economically rational, in that they assign fixed values to resources of fixed absolute qualities. However, humans show relative value perception – i.e. the value assigned to a resource is affected by many things extrinsic to the resource itself. Our research shows that ants also show relative value perception, judging the quality of a food source relative to their expectations. We also found that value perception is affected by value-neutral changes in food quality: ants devalue food which is different, but not worse, than what they expect. Most counterintuitively, we find that ants overvalue food which they had to work hard for. The many parallels between humans, non-human vertebrates, and insects suggest that relative value perception is a strongly adaptive behaviour, and that social insects can be valuable models of behavioural economic behaviour. Only by understanding how animals perceive value can we fully understand the decisions they make.

20.05.2019

Salvador Carranza - Forgotten in the ocean: the reptiles of the Socotra ArchIpelago as a model for the study of island biogeography and evolution

CMIMA, Barcelona, Spain

Abstract: Continental islands are very important hotspots of biodiversity and provide premier settings for studying the evolutionary and ecological processes that have resulted in such unique biotas. The Socotra Archipelago, in the western Indian Ocean, is a case example of an ancient continental fragment, a block of Precambrian Gondwanaland with a long biogeographic history. The Archipelago comprises four islands: Socotra, Darsa, Samha and Abd Al Kuri and is located in the Arabian Sea, situated 380 km southeast from the coast of Yemen and about 100 km east from the Horn of Africa (Somalia). Often referred to as the “Galapagos of the Indian Ocean”, it was designated a UNESCO World Heritage Natural site in 2008 as a result of its high level of endemicity at both specific and generic levels. Its ancient origin, long period of isolation from mainland, orographic diversity and unique climate affected by the monsoons have probably played important roles in the assemblage of its biota. However, a few studies have examined the congruence between these causal factors and the cladogenesis in the molecular phylogenies of various taxa. With 93.5% of the 31 species and 41% of the 12 genera being found nowhere else in the world, reptiles constitute the most relevant vertebrate group of the Socotra Archipelago and an excellent model to study in depth the role of historical and contemporary factors (i.e., island size and geographic isolation, biogeographic history and ecological disparity) in the origin and diversification of this unique faunal assemblage. In this talk I will review the work that we have been carrying on for the past years on the reptiles of the Socotra Archipelago to assess their origin and real diversity, to test the relative role of adaptive processes in the diversification of Socotran reptiles and compare the patterns of diversification and phenotypic differentiation of continental and Socotran sister groups to see whether island and continental species differ in their dynamics of diversification and eco-phenotypic evolution.

27.05.2019

Anita Narwani - Phyt to compete: evolutionary responses to competition for resources in phytoplankton

Eawag, Dübendorf, Switzerland

Abstract: Resource limitation is a major driver of ecological and evolutionary dynamics of all organisms, including phytoplankton. Short-term responses to resource limitation include plastic re-wiring of the molecular and metabolic phenotypes of cells. Yet little is known about the evolution of resource requirements and the molecular phenotype after longer-term selection by resource limitation. Can competitive abilities adapt to limiting resources? Do requirements for different resources evolve independently or are trade-offs intrinsic? What is the metabolic basis of this evolutionary adaptation? To answer these questions we combined experimental evolution of the green alga Chlamydomonas reinhardtii under multiple different types of resource limitation, with estimates of change in population-level resource requirements and protein expression. In my talk, I will present our findings from these experiments.

24.06.2019

Antonio Lazcano - Prebiotic chemistry and the origins of life: looking back again at the Miller experiment

UNAM, Mexico City, Mexico

Abstract: In a famous 1953 experimental simulation of the prebiotic environment, Stanley L. Miller, a graduate student of Harold Urey at the University of Chicago, demonstrated the ease with which organic compounds of biochemical significance could be synthesized under putative primitive conditions, supporting the idea of an heterotrophic origin of life. The robust nature of these reactions has been demonstrated by the finding that organic compounds are highly ubiquitous, as shown by their presence in carbon-rich meteorites, cometary spectra, and interstellar clouds where star and planetary formation is taking place. The remarkable coincidence between the monomeric constituents of living organisms and those synthesized in Miller-type experiments appears to be too striking to be fortuitous. The discovery of catalytically active RNA molecules provided considerable credibility to suggestions that the first living entities were largely based on ribozymes, in an early stage called the RNA world. At the time being the hiatus between the primitive soup and the RNA world is discouragingly enormous, and the problem of how RNA came into being remains an open one, shaping current attempts to study the conditions under which organic compounds were formed in the prebiotic environment.

01.07.2019

Cristina Tuni - A journey inside the nuptial gift of a spider

LMU-Munich, Germany

Abstract: In the Animal Kingdom males often offer edible donations to females during courtship or mating. These so-called nuptial gifts are intriguing male reproductive traits, taxonomically widespread and extremely diverse in form and function. Gifts have indeed evolved as a male mating effort to attract females and secure mating, as a form of parental investment due to the nutritious resources provided, and as a protective practice against cannibalistic mating partners. Despite being uncommon in spiders, Pisaura mirabilis has become one of the best-known model organisms in the study of nuptial feeding behaviour. Males of this species hunt for a prey, cover it in dense silk layers and offer it to females during courtship. Mating occurs only once the female accepts the donation and starts feeding from the gift. In this talk I will explore the evolutionary significance of gift giving in Pisaura mirabilis, addressing both, male and female reproductive interests. I will review findings from recent experimental laboratory studies and field surveys that have shed light on the evolution and maintenance of this male trait. Finally, I will illustrate how sexual selection and sexually antagonistic co-evolution have shaped this spiders’ fascinating mating system.

08.07.2019

Nigel Beebe - Evolution, distribution and movement of malaria mosquitoes of the Southwest Pacific

University of Queensland, Australia

Abstract: Much of my research revolves around integrating entomological procedures with molecular evolution and genetics tools to answer fundamental questions including: what mosquito species transmit disease pathogens, where do they exist, why are they there, as well as how do mosquito populations connect and move. Working out of the Southwest Pacific region (Papua New Guinea, the Solomon archipelago and Australia), I will present the journey to unravel the identity of our regional malaria mosquitoes. Starting with the development of molecular tools to separate cryptic mosquito species in Australasia, then exploiting these tools through productive collaborations with the Australian Defence Force to isolate the primary malaria vector species of the region from the many non-vector species. We also map their distributions and reveal, through population genetics studies, how these populations connect and move through this biogeographically complex region. Through this work, we are finding interesting host-feeding behaviour differences between and within species. This suggests the presence of gene flow barriers that permit this host-feeding behavioural variation to manifest and hint at some human fingerprints on these changes.

Winter Semester 2018/2019

12.09.2018

David Garfield - Single-cell and population genetic approaches to understand developmental evolution

Humboldt University, Berlin, Germany

Abstract: Mutations affecting non-coding, regulatory DNA play an important role in evolution and contribute disproportionately to human disease phenotypes. But identifying functional mutations in non-coding DNA is hard – typically we don’t know where to look, and when we do, we often find redundancy and degeneracy that complicate a simple mapping of genotype to phenotype. New advances in single-cell sequencing technologies, particularly single-cell ATAC-Seq, can help to delineate and identify regulatory elements active in different tissues. We recently used one such approach to construct a cell-type specific atlas of regulatory DNA used during embryonic development in Drosophila. In this talk, I will discuss our efforts to move this atlas one step farther, using population genetic information and allele-specific sequencing to understand how the impacts of selection and functional mutations are distributed across this regulatory landscape, with an eye towards the role that single-cell assays and evolutionary analyses can play in understanding the evolution of development across a range of taxa.

17.09.2018

Fritz Sedlazeck - Size matters: accurate detection and phasing of structural variations

Baylor University, Texas, USA

Abstract: In this presentation I will describe our latest work to obtain comprehensive genomes leveraging long and linked reads. The vast majority of NGS whole-genome data covers hundreds of thousands of samples with short illumina reads, which are unable to capture the full spectrum of genetic variation and genomic complexity. Such comprehensive variation is critical to understanding the full heritability and genetic foundations of human disease. In this seminar I will present our novel alignment strategy (NGMLR) for long read data (Oxford Nanopore and PacBio) and our novel Structural Variations (SVs) caller Sniffles. These two methods improved the accuracy for both technologies enabling the accurate and easy detection of SVs. This includes also nested events that we have previously been blind to or linked events connecting genes over multiple regions. We will discuss problems, characteristics and limitations of short reads. In addition, I will discuss the impact of these novel found SVs in cancer and other genomes with respect to RNA seq. In the end, I will highlight our current findings where we combine these long read technologies with linked reads to be able to phase SNV and SVs together to obtain a diploid genome per sample. These phased genomes are the most comprehensive representation of genomes up to date and we can now finally generate them within days.

22.10.2018

Kees van Oers - Genomic and epigenetic insights into the heritability of exploratory behaviour

Netherlands Institute for Ecology, Wageningen University

Abstract: For behavioural geneticists, the search for the hereditary mechanisms underlying quantitative traits traditionally focussed on the identification of underlying genomic polymorphisms such as SNPs, but this has not been very fruitful. It has now become clear that epigenetic mechanisms, such as DNA methylation, can consistently alter gene expression over multiple generations. Non-geneticists found out that these methylation patterns are prone to changes and such changes may be transmitted over generations. DNA methylation may therefore be an potential mechanism linking genetic and non-genetic inheritance. In this presentation, I will focus on exploratory behaviour in great tits (Parus major) as an example to highlight the successes and failures of modern genomic approaches. Furthermore, I will present preliminary results on the relative role of induced- versus genetic variation in DNA methylation for variation in exploratory behaviour. I will however also elaborate on the pitfalls when studying epi-genomics in an ecological model species. The explanation of variation in DNA methylation offers a great opportunity to combine genetic and non-genetic approaches to inheritance of complex traits.

12.11.2018

Markus Knaden - Olfactory-guided navigation in a desert ant

Max Planck Institute for Chemical Ecology, Jena, Germany

Abstract: The desert ant Cataglyphis inhabits the arid environment of North Africa where it forages individually for dead arthropods. Because of the ants’ high motivation to find the nest entrance and due to the almost lab-like conditions of their environment — the flat salt pan (where visual information and partly also olfactory information available to a homing ant can be easily manipulated) — Cataglyphis has become an important model for animal navigation. The ants use path integration, i.e. always compute their walking direction and distances and by that calculate their position to the nest entrance. In addition they learn visual and olfactory cues that help them pinpointing the nest entrance. The seminar will describe recent findings on olfactory navigation and will present how Cataglyphis combines the visual and olfactory navigational strategies efficiently.

19.11.2018

Krysztof Kozak - Drivers of diversification in Neotropical butterflies and beyond

Smithsonian Tropical Research Institute, Panama

Abstract: The richest diversity of life on Earth is found in the Neotropics, an area characterized by fast and dramatic environmental changes over the last 25 million years. Studies of complex adaptive radiations at the continental scale provide an opportunity to understand how speciation and adaptation have interacted with abiotic factors to produce high species richness. I focus on Heliconiini butterflies (Nymphalidae), a group of 77 species renown for spectacular diversity in aposematic wing patterns and formation of Müllerian mimicry rings. Phylogenetic analyses of entire genomes reveal rampant admixture across the genus Heliconius, with evidence for adaptive introgression at all five loci controlling the color and shape of the mimetic wing patterns. These findings suggest that the radiation ought to be represented as a network and imply that our ability to study traits in a comparative framework may be affected by the imposition of a bifurcating tree model.
To better understand the processes of diversification at the species level, I leverage the natural experiment formed by the radiations of Heliconius erato and H. melpomene, two widely spread species that mimic each other in a continental patchwork of 29 distinct wing pattern forms. Although the matching phenotypes have been used as an example of coevolution ever since Bates, it is unclear if the two species diversified in parallel. Using genomes of 170 H. melpomene and 260 H. erato and cognates collected widely across the Neotropics, I demonstrate substantial differences in the evolutionary history of the two species. Surprisingly, while mountain uplift left a strong signature on the early evolution of the two species, populations across the Amazon basin appear unexpectedly homogenous.
Finally, I will present first insights from a systematic survey of phylogenetic studies of American tropical taxa, highlighting perilously poor accessibility of published data. A re-analysis of a sample of chronograms for a wide spectrum of Neotropical taxa reveals that most extant species formed before Quarternary climatic disturbances. However, contrary to recent proposals, there is limited evidence for response to environmental disturbances in the Miocene, as many groups show surprisingly constant rates of diversification.
03.12.2018

Simone Immler - Haploid gametic selection in animals and its evolutionary consequences Cancelled

University of East Anglia, UK

Abstract: Biphasic life cycles with alternating diploid and haploid gametic phases are a traits shared by all sexually reproducing eukaryotes. Selection occurring during - even a short - haploid gametic phase may have substantial consequences for a wide range of biological processes including adaptation, inbreeding depression and sex chromosome evolution. While in plants, selection in haploid gametes is well established, in animals, the idea has remained largely untested. This is somewhat surprising given that particularly male gametes (sperm) are generally produced in large numbers but only few fertilise an egg offering an ideal opportunity for selection to act upon. We tested for selection on the haploid sperm genome in the zebrafish combining selection experiments with transcriptome and genome sequencing. We found clear evidence that the haploid sperm genome is more than just a silenced genome and selection at this stage has major fitness consequences for the following generations.

17.12.2018

Sonja Grath - Winter is coming – Cold tolerance in Drosophila

LMU Munich, Germany

Abstract: When organisms are faced with new environmental conditions, such as those caused by climate change or range expansion, they must adapt in order to survive. For evolutionary biologists, studying how species are formed and how they adapt to their environment are central questions. The evolutionary process by which individuals have their highest fitness in their local environment by means of natural selection is called local adaptation. Drosophila vinegar flies have been an important model system for biological studies since the early 1900s and Drosophila species having a worldwide distribution are excellent models for studying local adaptation. One example for local adaptation is adaptation to cold. Here, I will give insight into our work on cold tolerance in Drosophila ananassae. We used chill coma recovery time (CCRT) as proxy for cold tolerance in several fly strains. CCRT is the time required for a fly to recover from a cold-induced chill coma. We performed high-throughput gene expression analysis before and after a cold shock and conducted a quantitative trait loci (QTL) mapping experiment to identify candidate genes involved in cold tolerance. Finally, I will present our preliminary work on functional validation of these candidate genes by the means of CRISPR/Cas9-manipulated flies.

14.01.2019

Georg Oberhofer - Cleave and Rescue: a novel selfish genetic element and general strategy for gene drive

University of Göttingen, Germany

Abstract: Gene drive provides an opportunity to spread beneficial traits into a wild population. Here we describe a novel toxin-antidote type of synthetic selfish genetic element, Cleave and Rescue (ClvR), that is simple to build, and can spread a linked gene to high frequency in populations. ClvR is composed of two components. The first, germline expressed Cas9 and gRNAs (the toxin), cleave and disrupt versions of an essential gene located elsewhere in the genome. The second, a version of the essential gene resistant to cleavage, provides essential gene function (the antidote). ClvR spreads by creating conditions in which progeny lacking ClvR die because they have no functional copies of the essential gene. In contrast, those who inherit ClvR survive, resulting in an increase in ClvR frequency.

21.01.2019

Konrad Lohse - What determines genetic diversity in butterflies? Lewontin's paradox revisited

University of Edinburgh, UK

Abstract: The amount of genetic diversity segregating within a species is a function of its demographic and selective past and, in turn, determines its future evolutionary potential. Under the neutral theory genetic diversity is expected to be a linear function of population size. However, comparative studies have consistently failed to find any strong correlation between measures of census size and genetic diversity. Instead, a recent comparative study across several animal phyla identified propagule size as the strongest predictor of genetic diversity, suggesting that r-strategist which produce many offspring but invest little in each, have a greater long effective population sizes. I present a comparison of genome-wide levels of genetic diversity across 38 species of European butterflies. Analyses of these data suggest that across Lepidoptera genetic diversity varies over an order of magnitude and that this variation cannot be explained by differences in abundance, fecundity, host or geographic range. Instead, genetic diversity is correlated with genetic map length suggesting that the effect of selection on linked neutral diversity varies substantially between species.

Summer Semester 2018

16.04.2018

Martin Kapun - Clines and inversions as evidence for local adaptation in Drosophila melanogaster

University of Fribourg, Switzerland

Abstract: Clines, which are gradual changes of genotypes or phenotypes along environmental transects, are often taken as prima facie evidence for the action of spatially varying selection. However, only due to recent advances in sequencing technology it now becomes possible to compare genome-wide clinal patterns and test for alternative models. We use the Drosophila melanogaster system to study genomic diversity along a latitudinal temperature gradient at the North American east coast. We found evidence for steep and temporally stable clinal variation associated with In(3R)Payne, a common cosmopolitan inversion, that cannot be explained by demography alone. To learn more about the potential adaptive effect of this inversion, we compare karyotype-specific genomic and transcriptomic variation on different continents. We find genomic regions in the center of the inversion that are in strong linkage disequilibrium with the inversion breakpoints possibly as a result of selection for inversion-specific genetic variation. Finally, with the help of a newly founded population genetics consortium, we now expand the genome-wide analysis of clinal genomic variation to the yet largely unexplored European continent and find further evidence for the clinal variation of In(3R)Payne despite complex demographic patterns.

23.04.2018

Dieter Heylen - Evolutionary ecological interactions between songbirds, ticks and Borrelia burgdorferi s.l.: a community perspective

University of Antwerp, Belgium

Please note that this seminar will Mutations affecting non-coding, regulatory DNA play an important role in evolution and contribute disproportionately to human disease phenotypes. But identifying functional mutations in non-coding DNA is hard – typically we don’t know where to look, and when we do, we often find redundancy and degeneracy that complicate a simple mapping of genotype to phenotype. New advances in single-cell sequencing technologies, particularly single-cell ATAC-Seq, can help to delineate and identify regulatory elements active in different tissues. We recently used one such approach to construct a cell-type specific atlas of regulatory DNA used during embryonic development in Drosophila. In this talk, I will discuss our efforts to move this atlas one step farther, using population genetic information and allele-specific sequencing to understand how the impacts of selection and functional mutations are distributed across this regulatory landscape, with an eye towards the role that single-cell assays and evolutionary analyses can play in understanding the evolution of development across a range of taxa.

Abstract: Dieter Heylen is postdoctoral at the University of Antwerp (Biology department, Evolutionary Ecology group). He has more than ten years of experience in the study of ticks, songbirds and tick-borne diseases (TBD). He studies how the evolutionary ecology of host-parasites interactions relates to virulence, ecological specialization, adaptation, and spatio-temporal occurrence of ticks and TBD in songbirds. In more recent work, he investigates how ticks and birds contribute in the maintenance and establishment of TBD foci, by studying the reservoir competence of songbird species, and the vector-competence of bird-specialized tick species. He currently investigates how landscape determines TBD transmission flows over urbanisation gradients, and how isotope ratios of ticks can help in
elucidating transmission dynamics in the wild. In his seminar, he will consider the findings on the ecological interactions between ixodid ticks, common European songbirds and the Lyme disease causing bacteria Borrelia burgdorferi s.l..

30.04.2018

Chris Jiggins - Understanding porous species boundaries by studying butterfly genomes

University of Cambridge, UK

Abstract: A major undertaking in evolutionary biology is to link genotype to phenotype and understand the evolutionary changes that lead to adaptation and speciation. Here I will give an overview of our work on the brightly coloured Heliconius butterflies, showing that hybridisation makes species boundaries remarkably porous across the genome. Patterns of species relationships are highly variable across the genome, and this can offer insight into the process of speciation. There is little evidence for changes in recombination rate or inversion differences between species during speciation. Despite these loci of large effect, across the genome there is evidence for pervasive polygenic selection maintaining species differences in the face of ongoing gene flow, indicated by a strong association of admixture with regions of high recombination.

14.05.2018

Gergely Szollosi - Gene transfers, like fossils, can date the tree of life

University of Budapest, Hungary

Abstract: The geological record provides the only source of absolute time information to date the tree of life. But most life is microbial, and most microbes do not fossilize, leading to major uncertainties about the ages of microbial groups and the timing of some of the earliest and most important events in life's evolutionary history. I discuss our recent results, which show that patterns of lateral gene transfer deduced from analysis of modern genomes encode a novel and highly informative source of information about the temporal coexistence of lineages throughout the history of life. We use new phylogenetic methods to reconstruct the history of thousands of gene families and show that dates implied by gene transfers are strongly correlated with estimates from relaxed molecular clocks in Bacteria, Archaea and Eukaryotes. A comparison with mammalian fossils shows that gene transfer in microbes is potentially as informative for dating the tree of life as the geological record in macroorganisms.

04.06.2018

Rodrigo Medellin - How to do conservation science, implement it, and not die trying.

Instituto de Ecología, UNAM, Mexico

Abstract: Conducting research for conservation is, unfortunately, too often cut short or rarely implemented. I will discuss a few examples of research projects that have become official federal government programs with nation-wide implications. Mexico is the fifth country with the greatest biodiversity in the world. Challenges are thick and plentiful. Recently Mexico became the first country in the world to have an estimate of how many jaguars inhabit the country and the National Jaguar Strategy is fully in place and being implemented today. I will also speak about bighorn sheep and how a sustainable harvest has become the heart and soul of a strong conservation and development program for the Seri indigenous group. Bats represent about one-fourth of Mexico’s mammals and they include critically endangered and endangered species. The lesser long-nosed bat has been a focal species for my research and after 25 years it was recently delisted from Mexico’s Endangered Species List. The recovery implied lots of research, education, and specific conservation actions. The job of conservation professionals must include working with government and public to be effective.

11.06.2018

Tuncay Baubec - Function and regulation of mammalian DNA methylation

University of Zurich, Switzerland

Abstract: DNA methylation is a prevalent epigenetic modification involved in transcriptional regulation and essential for mammalian development. In mammalian genomes, DNA methylation is a prevalent modification that decorates the majority of cytosines. It is found at the promoters and enhancers of inactive genes, at repetitive elements, and within transcribed gene bodies. Its presence at promoters is dynamically linked to gene activity, suggesting that it could directly influence gene expression patterns and cellular identity. While the genome-wide distribution of this mark has been studied to great detail, the mechanisms responsible for its correct deposition, as well as the cause for its aberrant localization in cancers, have not been fully elucidated. I will present our recent efforts to elucidate the targeting preferences of DNA methyltransferases to the genome, and how chromatin states, histone modifications and DNA sequence help to guide deposition of DNA methylation to specific genomic sites.

18.06.2018

Homa Papoli - The evolution of sex chromosomes and sex-linked sequences in systems with female heterogamety

Uppsala University, Sweden

Abstract: Sex chromosomes evolved from a pair of autosomes between which recombination stopped. We can look at sex chromosome evolution at two levels. The first is looking at a large evolutionary time scale to investigate the steps involved in recombination cessation. In another level, we can look at the consequences of recombination cessation in the evolution of sex linked sequences. We used ostrich, as a representative of a basal clade of birds, together with several avian species to infer the chromosomal inversions involved in the evolution of sex chromosomes. To understand the consequences of recombination suppression on the evolution of DNA sequences, we used multiple avian species and a population level data of ostrich sex chromosomes to infer determinants of genetic diversity.

02.07.2018

Thomas Gilbert - Dogs and Wolves in Time and Space

University of Copenhagen, Denmark

Abstract: Despite the key position that dogs hold in the lives of many of us, and the extensive efforts of many previous scientific studies, a surprising amount remains to be learnt about our faithful friends. For example, considerable controversy exists over such basic questions as: When did we first domesticate the dog? Where was the domestication centre? Was there more than one? And perhaps most surprisingly, what was the dog even domesticated from? Given the extent to which we have both moved and shaped dog breeds in recent centuries, and taken a good stab at eradicating their wild relatives, it seems unlikely that analyses of modern genetic material alone will be able to solve these questions. As such deciphering dog domestication represents an exciting frontier on which palaeogenomic approaches stand to make enormous contribution, and indeed, in light of a vastly expanded reference dataset of contemorary genomic material, a number of intriguing findings are already coming to light.

Winter Semester 2017/2018

23.10.2017

Stefan Lüpold - Sperm wars: rise of the giants

University of Zurich, Switzerland

Abstract: Sexual selection drives the evolution of male ornaments and armaments used in gaining access to mates. However, whenever females mate with multiple males, sperm of different males will compete for fertilization. Selection for sperm that are both more competitive and better able to overcome the challenges of the female reproductive tract has brought about tremendous variation in sperm size and shape. I will discuss our recent work on the causes and consequences of variation in sperm form and function, including the evolution of the longest sperm ever measured. I will further discuss how males trade off the allocation of their limited resources between producing masses of high-quality sperm and the costly ornaments and armaments to gain mating opportunities in the first place.

 

6.11.2017

Christiane Fuchs - Estimating single-cell heterogeneities from small cell populations

HelmholtzZentrum München, Germany

Abstract: Cell-to-cell variation in gene expression occurs in a number of biological contexts, such as development and cancer. Discovering such heterogeneities from large bulks of cells is impossible due to the inherent population averaging. The analysis of single cells, on the other hand, is challenging because of e.g. technical noise. Here, I show that we can infer single-cell regulatory states by statistically deconvolving measurements from small groups of cells. This averaging-and-deconvolution approach allows us to quantify single-cell heterogeneities while avoiding the measurement noise of global single-cell techniques. Application of the statistical technique to breast epithelial tissues helped gain new insights about some breast cancer associated genes. I will outline how the method can be used to detect transcriptomic heterogeneity in leukemia cells within the CRC 1243 “Cancer Evolution”.

13.11.2017

Robert Page - Beyond the Superorganism: how social mechanisms evolve

Arizona State University, USA

Abstract: More than a century ago (1911) William Morton Wheeler proposed that social insects should be considered organisms because they have the defining properties of individuals "... a complete, definitely coordinated and therefore individualized system of activities, which are primarily directed to obtaining and assimilating substances from an environment, to producing other similar systems, known as offspring, and to protecting the system itself and usually also its offspring from disturbances emanating from the environment. The three fundamental activities enumerated in this definition, namely nutrition, reproduction, and protection ... ." In 1928 Wheeler first used the term "superorganism" to describe social insects, which became a permanent part of the vocabulary of social insect biologists. But, Wheeler's superorganism was little more than a metaphor created to explain the evolution of cooperative behavior, something he thought impossible with Darwinian selection, focused on the struggle for life and reproduction, best depicted by the phrase of Herbert Spencer "the survival of the fittest". Over the past century the metaphor has gone through phases of use and abuse and at least two different "revivals", but always as a metaphor, a conceptual scaffold on which analogies are hung, offering a way to explain observed social phenomena, but little in the way of predictive hypothesis and new questions. What is missing, in my view, is a theory of the superorganism that incorporates and integrates the following components: 1) how cooperation resulting in reduced reproduction (altruism) evolves (a major theoretical enterprise for 50 years), 2) how colony level selection affects multiple levels of biological organization -- genes to societies, 3) the mechanisms by which coordinated division of labor emerges from a group of individuals without a global control system and how such mechanisms evolve. I will discuss a 25-year experiment with honey bees where I addressed components 2 and 3.

11.12.2017

Daniel Jeffares - Populations, genomics and transposon mutagenesis in the (fission) yeast model

University of York, UK

Abstract: The fission yeast Schizosaccharomyces pombe is an important model for molecular and cellular biology. In contrast to the budding yeast, we knew very little about the diversity, ecology or evolution of the species until very recently. I’ll introduce what little is known about the ecology of this yeast (1), and then describe three of my studies of genome diversity and function. First, I’ll outline our study of genomic and phenotypic diversity, where we describe population structure, date the dispersal of the species and show that genome-wide association studies are feasible in this species (2). Secondly, I’ll describe our analysis of structural variation from short read data demonstrating that copy number variants both contribute to heritable traits, and are unstable (3). On a slightly different track, I’ll describe our recent analysis of saturating transposon mutagenesis in S. pombe (unpublished). In this study, we generated very dense transposon insertion libraries using the Hermes transposon, to one insertion per 14nt of the genome. We developed a hidden Markov Model that uses the transposon insertion density to classify the relative importance of each position in the genome. We show that HMM states assign similar functional constraints to comparative genomics and genetic diversity, but with far higher resolution. This data will bring us closer to quantifying the functional significance of every base in the genome.

08.01.2018

Jonathan Jeschke - Hierarchies of hypotheses and other new tools for research synthesi

Freie Universität Berlin, Germany

Abstract: Massive amounts of ecological and other data are accumulating each year. In the current era of Big Data, the statement by Naisbitt that “we are drowning in information but starved for knowledge” from the 1980s seems to be more applicable than ever before. We arguably lack effective tools for research synthesis at a macro level, tools that help “connect the dots.” I will present new synthesis tools – Hierarchies of Hypotheses (HoHs), networks of major hypotheses and research questions, among others – and give examples for applications of these tools in invasion ecology and biogeography.

15.01.2018

Daniel Hooper - Chromosome inversions and avian speciation

Cornell University, USA

Abstract: Species divergence is associated not just with the accumulation of molecular changes in DNA composition but oftentimes also with structural changes to the genome, such as chromosomal inversions. Because the speciation process is protracted, it appears that gene flow among incipient species is common and may often influence the generation of reproductive isolation. While gene flow generally acts to homogenize differences between diverging populations it can, paradoxically, play a creative role in speciation by promoting the evolution of chromosome inversions that encompass and keep together sets of locally adapted genes. Chromosome inversions commonly distinguish the genomes of closely related bird species and are increasingly found as polymorphisms within species. Why? I will first share results from a pair of comparative studies on inversion evolution using cytological data from more than 400 species in the most speciose order of birds, the
passerines, in order to test support for alternative models of inversion fixation (1,2). Secondly, I will share results from an ongoing project examining the extent to which chromosome inversions contribute to reproductive isolation in an avian hybrid zone.
1. Hooper, D. M. & T. D. Price. Rates of karyotypic evolution in Estrildid finches differ between island and continental clades. 2015. Evolution 69:890-903.
2. Hooper, D. M. & T. D. Price. Chromosomal inversion differences correlate with range overlap in passerine birds. 2017. Nature Ecology & Evolution 1:1526-1534.

22.01.2018

Christian Schlötterer - Evolution of gene expression in Drosophila

VedMedUni Vienna, Austria

Abstract: Temperature is a major environmental factor affecting many traits, including gene expression. While at benign temperatures the gene expression pattern is very similar between genotypes, at more extreme temperatures large genotype specific differences can be detected. Most of the differences in expression can be attributed to trans-effects. Nevertheless, it is not apparent to what extent these differences in gene expression reflect adaptive responses. We address this question by exposing a natural Drosophila population to new temperature environments and study the change in gene expression after more than 60 generations of experimental evolution. We show that the ancestral plasticity in natural Drosophila populations is most likely adaptive, because after 60 generations most of the ancestrally plastic genes increased their plasticity at the extreme laboratory environments.

29.01.2018

Katie Peichel - Genetics of adaptation in sticklebacks: the roles of pleiotropy and linkage

University of Bern, Switzerland

Abstract: Despite recent progress, relatively little is known about the specific genetic and molecular changes that underlie adaptation to new environments. Stickleback fish have been at the forefront of research to uncover the genetic and molecular architecture that underlies adaptation and speciation. A wealth of quantitative trait locus (QTL) mapping studies in sticklebacks has provided insight into the distribution of effect sizes during adaptation and has also revealed that several regions of the genome contain more loci than expected for traits involved in adaptation. It is unknown whether these trait clusters result from tight physical linkage of multiple genetic changes responsible for different traits, or from a single genetic change with pleiotropic effects. I will discuss recent research in my group that is focused on disentangling the roles of pleiotropy and linkage in adaptation, using both genome-wide approaches and more focused studies of specific loci with a major effect on adaptation.

05.02.2018

Samantha Patrick - Life history correlates of consistency and variability in behaviour

University of Liverpool, UK

Abstract: How individuals obtain the resources they need for survival and reproduction is integral to their fitness. Individuals may differ in the way in which they search for food or the spatial and temporal consistency in their foraging strategy. The fitness consequences of short and long term consistency are poorly understood and whether differences within populations emerge due to adaptive strategies or constraints linked to quality has rarely been studied. In this presentation I will discuss the emergence of individual differences in the exploration-exploitation trade off, indicative of differences in searching behaviour. I will present evidence of short and long term consistency in foraging area and habitat choice and examine whether specialists and generalist coexist or whether specialisation is always adaptive. I will look at how these foraging traits change over the lifetime of individuals and reveal the importance of intrinsic drivers in shaping the links between foraging and fitness.

Summer Semester 2017

29.05.2017

Kris Murray - "Pathogeography - the biogeography of human infectious diseases"

Imperial College London, UK

Abstract: With infectious diseases having repeatedly altered the course of human history, and still responsible for almost a fifth of the global burden of disease, understanding the distributions of infectious diseases is a central public and global health objective. I will discuss some recent work in which we show that human infectious diseases exhibit striking biogeographic grouping patterns at a global scale, reminiscent of “Wallacean” zoogeographic patterns. This result is surprising, given the global distribution and unprecedented connectivity of humans as hosts and the homogenizing forces of globalization; despite these factors, infectious disease assemblages appear to remain fundamentally constrained in their distributions by ecological barriers to their dispersal or establishment. Biogeographic processes thus appear to provide an overarching context in which other factors promoting infectious disease emergence and spread are set, providing a potentially useful prior with which to evaluate a range of disease risks and potential management interventions.

12.06.2017

Robert Whittaker - "Oceanic island biogeography through the lens of the General Dynamic Model"

University of Oxford, UK

Abstract: The general dynamic model of oceanic island biogeography (GDM) provides a theoretical framework incorporating the dynamics of island platforms alongside the key biological drivers of immigration, extinction and speciation. It provides an essentially non-equilibrium framework generating novel predictions for emergent diversity properties of oceanic islands and archipelagos. Based on efforts of the biodynamics of islands workshop group I review progress, both in testing the GDM’s predictions and in developing and enhancing ecological-evolutionary understanding of oceanic island systems, through the lens of the GDM. The presentation considers such themes as: 1, what we have learnt from species-area relationships for remote islands; 2, macroecological tests of the GDM using a space-for-time rationale; 2, extensions of theory to islands following different patterns of ontogeny; 3, the implications of GDM dynamics for lineage diversification and trait evolution; 4, the potential for downscaling GDM dynamics to local-scale ecological patterns and processes within islands; 5, island theory and non-native species.

19.06.2017

Justin Crocker - "Decoding evolution and development: from enhancer structure to function"

EMBL Heidelberg, Germany

Abstract: In animals, Hox transcription factors define regional identity in distinct anatomical domains. How Hox genes encode this specificity is a paradox because different Hox proteins bind with high affinity in vitro to similar DNA sequences. Here, I will show that the Hox protein Ultrabithorax (Ubx) binds specifically to clusters of very low-affinity sites in Drosophila. These low-affinity sites conferred specificity for Ubx binding in vivo, but multiple clustered sites were required for robust expression when embryos developed in variable environments. Although most individual Ubx binding sites are not evolutionarily conserved, the overall enhancer architecture—clusters of low-affinity binding sites—is maintained and required for enhancer function. Natural selection, therefore, works at the level of the enhancer, requiring a particular density of low-affinity Ubx sites to confer both specific and robust expression. Finally, I will discuss results that suggest that low-affinity sites drive efficient transcription by utilizing nuclear microenvironments with high concentrations of transcription factors and cofactors. Mechanisms that generate these microenvironments are likely to be a general feature of eukaryotic transcriptional regulation.

26.06.2017

Martin Wikelski - "The ICARUS Project"

Max Planck Institute for Ornithology, Konstanz, Germany

Abstract: The goal of the ICARUS (International Cooperation for Animal Research Using Space) Initiative is to observe global migratory movements of small animals through a satellite system. Global data about animal movements are indispensable in our today international networked world to understand how to safe human health and wildlife simultaneously. To this date scientists are unable to follow small animals and insects on their long journey. Billions of songbirds move every year from continent to continent. Also many bats and numberless species of insects manage long distances and in doing so possibly move from one continent to another. We do not know exactly. However, this knowledge plays a fundamental role to understand the propagation of pathogens through their hosts for instance to preserve ecosystem services or to predict natural disasters through intelligent sensors of animals. To remedy the worldwide lack of knowledge about the distribution and the individual migratory habits of small animals and insects, an international consortium of scientists got the ICARUS project underway in 2002. With the data generated by ICARUS, scientists expect revolutionary new insights about life, behavior, vital functions and death of the animals on our planet. The globally collected data allows us among other things conclusions for the spread of diseases (zoonosis), understanding of climate change and disaster forecast. The research results to be expected here are of invaluable importance for mankind and finally for life on earth.

17.07.2017

Susanne Foitzik - “The evolution of division of labor and parasite defense: from the phenotype to changes in gene expression and regulation”

University of Mainz, Germany

Abstract: Social insects show fascinating behaviours, from slavery, over social immunity to an effective division of labour in their societies. In this talk, I will give insights into the evolution and molecular basis of behaviour in ants and present recent results that reveal, which proteins, genes and gene regulatory mechanisms are involved. In most insect societies, division of labour among workers is age dependant and we demonstrate this also for the small Temnothorax ants. Transcriptome analyses allowed us to identify candidate genes, which control the behavioural transition from brood care to foraging behaviour. RNAi-mediated knockdown of a brood care gene, vitellogenin-6, showed that division of labour is indeed controlled via response thresholds to social cues, which shift with gene expression. Inhibition of histone-acetyltransferase revealed that behavioral transitions in ant workers are controlled by histone acetylation via an alteration of gene expression. Parasites can also affect ant behaviour, either by direct manipulation or by selecting for behavioral defense mechanisms. Our study on a cestode parasite and its ant host show, that parasite infection not only affects behaviour (by lowering general activity), but also increases longevity. Proteome analyses of proteins released by the cestode into the host indicate that the parasite directly manipulates the host phenotype. Finally we investigate the evolution of slavery in ants and can show, which genes are differently expressed during slave raids and host defence in three slavemakers and their three hosts. We could functionally characterize some of these candidates using RNAi. Selection analyses reveal that different genes are under selection in independent origins of slavery, suggesting convergent evolution of these fascinating behaviours.

24.07.2017

Meike Wittmann - "Fluctuating balancing selection and its effects on neutral genetic diversity”

University of Vienna, Austria

Abstract: For organisms with several generations per year, seasonally fluctuating selection can be a powerful mechanism to maintain genetic polymorphism. For example, an allele favored during summer may stably coexist with an allele favored during winter, a form of balancing selection. Despite intense debate over decades, it is still unclear how much of the variation observed in the genomes of natural populations is due to balancing selection. In recent years, evolutionary biologists have started scanning genomes for genetic footprints of balancing selection (e.g. regions of increased diversity and positive Tajima's D). However, these scans have generally assumed the simplest form of balancing selection where alleles are maintained at constant frequencies over time. There is currently insufficient theory to tell us what genetic footprint to expect under seasonally fluctuating selection, and how to distinguish it from neutrality but also from other forms of balancing selection. In this talk I will present results from coalescent models and stochastic simulations to characterize the impact of fluctuating balancing selection on neutral genetic diversity at various scales: at closely linked sites, at the scale of the chromosome, and at the genomic scale.

Winter Semester 2016/2017

31.10.2016

Nico Posnien - "Systems-Evo-Devo: Evolution of developmental gene regulatory networks”

University of Göttingen, Germany

Abstract: The size and shape of an organism and its organs is tightly controlled during embryonic and postembryonic development to ensure proper functionality. However, in the light of the breath-taking diversity of body forms observed in nature, adult features are certainly targets for evolutionary changes. This contradiction suggests that developmental gene regulatory networks (GRNs) are constrained to a certain level, but nodes within this network are prone to change to give rise to morphological divergence.
We have previously shown that the three closely related Drosophila species D. melanogaster, D. simulans and D. mauritiana exhibit natural variation in eye size and overall head morphology. In this survey, D. melanogaster has the smallest eyes and D. mauritiana has the largest eyes. The aim of our research is to identify flexible nodes within the GRN underlying adult head formation in these three Drosophila species. To this end, we combine unbiased genome-wide approaches like quantitative trait loci (QTL) mapping and comparative transcriptomics with developmental genetics and geometric morphometrics to identify genes and developmental processes responsible for the observed differences in head morphology.
Our genome-wide expression analysis of different developmental stages of eye and head development shows that many genes that are differentially expressed between D. melanogaster and D. mauritiana are regulated by the GATA transcription factor Pannier (Pnr). Using interspecific crosses with D. melanogaster pnr deficiency lines, we provide further support for an involvement of the pnr locus. Eventually, we place pnr in the developmental gene regulatory network underlying eye development. All this data strongly suggests that divergence at the pnr locus is likely to be responsible for the morphological differences between D. melanogaster and D. mauritiana.

21.11.2016

Qi Zhou - "Evolution of sex chromosomes of flies, birds, snakes and beyond"

University of Vienna, Austria

Abstract: Sex is a nearly universal biological feature, and is determined by sex chromosomes in many, but not all the eukaryotes. After the birth of sex-determining genes, X and Y chromosomes start their separate evolutionary trajectories and form opposite patterns of gene content and epigenomic landscapes. Over the past several years, I have studied birds, snakes and Drosophila species, and will use them as examples to introduce my current and future research. We have studied complete genomes of 50 bird species. We reconstructed complex scenarios of recombination loss between sex chromosomes, caused by Z- or W-chromosome inversions, and uncovered a great diversity of their evolution rate comparing to the mammalian XY systems. In Drosophila, we show Y chromosomes can degenerate very quickly, manifested by increased bindings of heterochromatin modification, and decreased bindings of euchromatin modification together. This process is not random across the Y-linked regions, but constrained by the ancestral chromatin configuration. It is probably triggered by the vulnerability of Y against the transposable element insertions, and further results in the chromosome-wide silencing of Y-linked genes. It also creates an arms-race between the piRNA and TEs, which forms my main topic of research in Vienna for the next five years.

05.12.2016

Tom Tregenza - "Ageing in the wild"

University of Exeter, Cornwall, UK

Abstract: In recent years a growing number of field studies have identified senescent declines (age-related degeneration) across a broad range of taxa. However, studies examining changes in behaviour are rare, and insects in their natural context have hardly been studied all, despite their importance as laboratory model systems. I will describe our decade long study of a population of wild crickets which has allowed us to analyse patterns of mortality and the effect of age on a suite of traits including naturally and sexually selected behavioural traits measured at the individual level. We find substantial evidence of actuarial senescence, with the probability of death increasing with individual age. However the nature of these declines varies among years and the key prediction that males should age faster than females is only true in some years. Behavioural traits show a range of patterns, although evidence of senescence is abundant. I will discuss potential explanations for the striking variation we observe.

12.12.2016

Patrik Fink - "The challenged consumer - aquatic herbivores’ response to variable resource quantity and quality”

University of Cologne, Zoological Institute, Workgroup Aquatic Chemical Ecology &
Heinrich-Heine-University of Duesseldorf, Institute for Zoology and Cell Biology, Germany

Abstract: Herbivores play a key role in aquatic food webs as they are responsible for the trophic transfer of photosynthetically assimilated carbon into the animal food web, which makes them crucial for the functioning of marine and freshwater ecosystems. It is hence of paramount importance for ecologists to understand the reasons for constrained efficiency of the transfer of matter and energy at the plant-herbivore interface, but also the potential compensation mechanisms that consumers have evolved to cope with such constraints. This relies on a firm understanding of food web structure and the physiological ecology of the respective organisms. In this presentation, I summarize some of my recent research on the structure of aquatic food webs with particular focus on aspects of biodiversity and the impact of invasive species. I highlight some of the nutritional constraints for the efficient transfer of algal biomass to benthic and pelagic herbivores and their consequences for herbivore fitness. I further discuss potential strategies of aquatic herbivores to compensate or overcome nutritional constraints through the evolution of physiological and/or behavioural adaptation strategies and show case studies for such strategies from both marine and freshwater environments.

09.01.2017

Siegfried Roth - "The evolution of dorsoventral patterning in insects"

University of Cologne, Germany

Abstract: Toll-dependent patterning of the dorsoventral axis in Drosophila represents one of the best-understood gene regulatory networks. However, its evolutionary origin has remained elusive. Outside the insects Toll is not known for a patterning function, but rather for a role in pathogen defense. I will present our recent findings on the evolution of dorsoventral patterning in insects. In particular, I will describe our work on a hemimetabolous insect, the milkweed bug Oncopeltus fasciatus, whose lineage split from Drosophila’s more than 350 million years ago. In Oncopeltus, Toll is only required to polarize a dynamic BMP signaling network. Modeling of this network reveals that shallow Toll signaling gradients are sufficient to initiate axis formation. Dynamic BMP signaling combined with long-range, shallow Toll signaling gradients can explain the twinning of embryos upon egg fragmentation which has been observed in many insect lineages except the higher dipterans to which Drosophila belongs. Broad Toll signaling during early embryogenesis may also explain the emergence of Toll’s patterning function from a prior role in protecting the egg and embryo against microbial attacks.

23.01.2017

Stefan Laurent - "Using population genetics and field experiments to study molecular evolution at Agouti: a gene underlying coat color adaptation in the Nebraskan deer mouse"

University of Lausanne, Switzerland

Abstract: Natural selection is widely accepted as the evolutionary force driving adaptation in natural populations, but in higher organisms, there are only a limited number of adaptive events that have been described not only at the phenotypic but also at the molecular and ecological level. One of these well-described adaptations is the evolution of cryptic coat color in the deer mice (Peromyscus maniculatus) living in the Nebraskan Sand Hills. In this region, a large field of dunes established around 10 to 15 thousand years ago and caused the color of the soil to become significantly lighter than the ancestral (and currently surrounding) darker soils. This change in substrate color is thought to have had dramatic consequences for dark-coated wild-type individuals because they are preys of visually-hunting predators. It has been hypothesized that by increasing their camouflage, light-coated mutants increase their fitness and that strong and recent positive selection, acting on the Agouti gene, is responsible for the correlation between substrate color and coat color observed in populations on and off the Sand Hills. In this talk I will present the results of population genomic analyses that improved our understanding of the selective sweep on Agouti and show that several mutations and recombination events contributed to this adaptive event. I will also present the results of a manipulative field experiment in which survival rates and genome-wide allele frequency changes (before/after predation) have been measured in controlled populations of dark and light populations on and off the Sand Hills. The results of this experiment highlight the reproducibility of positive selection on Agouti in this system. Finally, I will discuss statistical issues related to the analyses of this new type of temporal population genetic data.

06.02.2017

Daniel Wegmann - "Inferring evolutionary processes from temporal and ancient data"

University of Fribourg, Switzerland

Abstract: Evolutionary change is the result of both genetic drift and selection, but disentangling these two processes has been proven difficult. Recent technological progress now hold promise to address this by looking at data from many individuals and the entire genomes. I will discuss recent statistical advances to make use of such new data and argue that power is maximized by investing into larger samples or over larger temporal scales, rather than the accuracy of individual samples. I will first discuss the potential of time series data to observe evolutionary change and introduce a novel method to jointly infer demography and selection from such data. As an example I will identify the loci conferring resistance to Influenza viruses that were evolved experimentally in the presence of Oseltamivir. Second, I will discuss statistical challenges along with solutions to include ancient DNA into evolutionary analysis to increase the temporal scale at which we quantify evolution of long-lived organisms such as humans. As an example I will discuss our latest insights into the spread of farming into Europe that we gained from sequences of the very first farmers in both the fertile crescent as well as the Aegean region. Interestingly, these data suggest that while farming spread from the Aegean mainly by the movement of people, it initially reach the shores of Europe by cultural diffusion.

Summer Semester 2016

09.05.2016

Katja Räsänen - "Phenomics of maternally mediated adaptive divergence: insight from Rana arvalis and Salvelinus alpinism"

EAWAG Zürich, Switzerland

Abstract: Natural selection acts on the composite phenotype of organisms, meditated through a web of interactions between the external environment and genotype. One important source of phenotypic variation – especially at early life stages - are maternal effects, which can influence speed and direction of evolutionary responses and facilitate rapid local adaptation. Katja will focus on egg coats (maternally derived extra-embryonic membranes) as facilitators of adaptive divergence along an acidification gradient in the moor frog (Rana arvalis), and on egg size as facilitators of resource polymorphism evolution in sympatric arctic charr (Salvelinus alpinus). She will provide insight to the molecular and functional basis of these maternal effects, and emphasize that early life stage traits can play an important role in evolutionary diversification.

13.06.2016

Tobias Uller - "Adaptive evolution of inheritance"

Lund University, Sweden

Abstract: Evolution by natural selection requires three conditions: variation between individuals, that some variants leave more descendants than others, and that offspring resemble their parents. The high-fidelity replication of DNA gives the impression that inheritance can be treated as a fixed channel of transmission. However, there is more to heredity than genes. Treating parent-offspring similarity as an evolving feature of life cycles allows us to address how mechanisms of inheritance change under natural selection. This sheds light on the adaptive evolution of a suite of transgenerational phenomena, from environmental maternal effects to incomplete epigenetic resetting. This perspective demonstrates that epigenetic and behavioural mechanisms can play several roles in evolution – from being a cause of phenotypic variation to enabling adaptive transgenerational plasticity and stable transmission of species-typical phenotypes.

20.06.2016

Marc Naguib - " The evolution of communication: information flow in territorial animal societies"

Wageningen University, The Netherlands

Abstract: Many animals hold specific social relations to other individuals, like their mates, relatives, other group members, or territorial neighbours. To maintain such relations, communication is essential. Among such signals, advertisement signals are particularly interesting as they attract and repel others and are important in mating decisions and decisions to defend resources. To obtain information from such signals individuals often need move around to be in range of the signals, so that communication and spatial relations are strongly linked. This presentation will provide an overview over signalling, communication networks and spatial behaviour in animals, mainly using our long-term research on nightingales (Luscinia megarhynchos) and great tits (Parus major) as example. This includes also a current large-scale automatized radio-tracking project where we integrate social and communication networks to better understand the functioning on territorial animal societies.

04.07.2016

Leonida Fusani - "The interplay between condition, food, and rest in migratory birds"

University of Vienna, Austria

Abstract: During migration, birds experience continuous changes in body condition. During long migratory flights over ecological barriers, such as deserts and seas, they use most of their energy stores. Therefore, birds spend a considerable amount of time at so-called stopover sites to refuel between flights. In the last decade, we studied the mechanisms controlling decision-making at stopover sites, that is, how birds decide whether they are ready to resume migration or not. Our work showed that when controlling for environmental factors, the extent of subcutaneous fat stores is the best predictor of the migratory disposition and in fact of the duration of the stopover. However, food has a strong effect on migratory behaviour, which is not necessarily linked to changes in body mass. As migratory birds literally eat their guts during migration, they need to rebuild their gastrointestinal tract before they can restore their energy reserves. This requires a fine control of activity patterns, because refuel occurs during the day whereas migration is mostly nocturnal. In this talk, I will present some highlights of our recent research on stopover physiology.

 

Winter Semester 2015/2016

23.11.2015

Beatriz Vicoso - "Frequent sex chromosome turnover in dipteran insects"

IST Austria

Abstract: In many species, sex is determined by a pair of sex-chromosomes, such as the X and Y chromosomes of mammals. Although they originally arise from a pair of autosomes, X and Y chromosomes eventually acquire very specialized biologies. This is thought to prevent them from reverting to autosomes, so that the acquisition of differentiated sex chromosomes has been assumed to be an irreversible state.

Dipteran insects (flies, mosquitoes and midges) generally have XY sex chromosomes and a conserved karyotype, consisting of six chromosomal arms (5 large rods and a small dot). The XY pair of Drosophila melanogaster was assumed to be ancestral and shared by most Dipteran insects, an assumption supported by the apparent homology of the mosquito and Drosophila X-chromosomes.

Our genomic analysis of 37 species of Diptera shows that, contrary to this hypothesis, there is tremendous diversity of sex chromosome karyotypes in this group. First, we found that the X of Drosophila is not ancestral to Diptera. Instead, the ancestral X corresponds to the small “dot chromosome”, which then reverted to an autosome in Drosophila, demonstrating that such X to autosome reversals can happen. We also identified species with undifferentiated sex chromosomes, and others where a different chromosome replaced the dot as a sex chromosome, or where up to three chromosomes became incorporated into the sex chromosomes.

While surprising in itself, this diversity also allows us to test theories of sex chromosome evolution more systematically than was previously possible. Our multi-species transcriptome analysis shows that dosage compensation has evolved multiple times in flies, consistently through upregulation of the single X in males. However, X chromosomes generally show a deficiency of genes with male-biased expression, possibly reflecting sex-specific selective pressures. These species thus provide a rich resource to study sex chromosome biology in a comparative manner, and show that similar selective forces have shaped the unique evolution of sex chromosomes in diverse fly taxa.

30.11.2015

Denis Reale - "Pulses resources and the ecology of eastern chipmunks"

UQAM, Montreal, Canada

Abstract: Animal populations have to deal with temporal and spatial availability of resources. Pulsed resources represent an extreme case of resources fluctuation in a way that they are produced in huge amounts during restricted periods and are almost inexistent the rest of the time. Pulsed resources create a challenge to animals exploiting them, as these consumers have to find ways to adjust their life history in response to these fluctuations. This is the case of the eastern chipmunk (Tamia striatus) a small Sciurid commonly found in North-American forests, and that relies mainly on the American beech (Fagus grandifolia) in the northern regions of its distribution range. Once every 2-3 years, beech trees produce massive amounts of seeds, during what is generally called a masting even. Although eastern chipmunks can feed on different plants, small invertebrates, and other sources of food, they rely mostly on beech seeds for their reproduction and winter survival. Chipmunks store seeds into their burrow over the summer and the fall, and use these resources for their winter needs. Here we show the case of a chipmunk population in Southern Quebec that we have followed for 10 years. In this individually marked population we have collected information on individual burrow locations, habitat characteristics, behaviour, physiology, and genetics. Using this long-term data set we show how chipmunks life history and ecology depends strongly on beech seed fluctuations. Chipmunk reproductive cycles and population demography depend on masts; chipmunks do not reproduce every year, but concentrate their reproductive effort around masting events. Masts affect winter torpor, dispersal and the genetic structure of the population. Furthermore, because of the temporal fluctuation of seed production, chipmunks born at different cohorts show different life history strategies and personalities, and our results show cohort-dependent personality types fitted with specific life histories. Our results shed light on how fluctuation in ecological conditions may maintain personality differences and relationships between animal personality and life history.

07.12.2015

Angela Hay - "Morphomechanical innovation drives explosive seed dispersal"

MPI Cologne

Abstract: How mechanical and biological processes are integrated across different scales to create complex traits is largely unknown. In this work, we combine biological, mathematical, and computational approaches to understand the mechanical basis for explosive seed dispersal - a key life history trait underpinning invasive behavior in the common weed Cardamine hirsuta. We have exploited the experimental tractability of C. hirsuta - a close relative of the model organism Arabidopsis thaliana – to understand the mechanism of explosive pod shatter and provide insights into the origin of this striking trait.

14.12.2015

Krushnamegh Kunte - "Speciation and morphological diversification in Papilio swallowtail butterflies"

NCBS, India

Abstract: The hallmark of life on earth is morphological diversity, which is often represented in spectacular sexually dimorphic and polymorphic phenotypes across species. I will address ecological pressures and genetic mechanisms that shape the evolution of morphological diversity with three stories of the iconic PapilioSwallowtail Butterflies. First, I will discuss the species radiation of Papilio in the geologically complex Indo-Australian Region, which has shaped reproductive isolation and speciation in Papilio as a function of biogeographic separation. Second, I will show how Batesian mimicry has driven wing pattern diversification, sexual dimorphism and polymorphism in Papilio. I will show that frequency dependent natural selection (predation) and sex-specific advantages of mimicry appear to have driven most of the wing pattern diversification in Papilio and related tropical butterflies. Finally, I will present the remarkable wing pattern polymorphism in Papilio polytes, which is an emerging genetic model system. Earlier I showed that doublesex, a transcription factor that regulates sexual differentiation in insects, also controls this female-limited mimetic polymorphism. I will present some recent work on the genetics of this polymorphism, which is beginning to characterize molecular variation in doublesex in nature. Thus, in this talk I will present a broad picture of the evolution of morphological diversification with respect to ecological and biogeographic processes, and its genetic and developmental regulation.

18.01.2016

Amanda Bretman - "No fly is an island: how Drosophila respond to socio-sexual environments"

University of Leeds, UK

Abstract: We all modify our behaviour in different social situations to adapt, fit in or to become more competitive. Fruit flies also have complex social lives, aggregating independently of any resources, engaging in social learning, forming social networks and having a genetic propensity for different types of social environments. Using Drosophila melanogaster fruit flies as a model, we can investigate both the fitness consequences of changes of social environment and the mechanisms by which individuals can respond to such changes.
One aspect of the social environment that has a particular impact on males is how much mating competition (both before and after mating) they encounter. Theory predicts that if males can mate more than once they need to trade-off current and future mating opportunities, hence they should modify their mating effort at a particular mating depending on the amount of competition they face. Males of many species use plastic strategies to cope with this uncertainty, taking cues from the presence of other males or the mating status of females, and making adjustments to behaviour and ejaculate content accordingly. In D. melanogaster, after being exposed to a potential competitor, males mate for longer and transfer a higher quality ejaculate. This is has fitness benefits, at least in the short term, but is costly. By combining behavioural and life history data with transgenics and transcriptomics, we can investigate how such responses are coordinated and regulated, an important step in understanding how sophisticated, flexible social behaviours evolve. We are also starting to use this paradigm to investigate other consequences of social contact on traits such as ageing, immunity and cognition.

25.01.2016

Jochen Blath - "On the role of dormancy in population genetics"

TU Berlin, Germany

Abstract: We analyse patterns of genetic variability of populations in the presence of a large seed bank with the help of a new coalescentstructure called the seed bank coalescent. This ancestral process appears naturally as scaling limit of the genealogy of large populations that sustain seed banks if the seed bank size and individual dormancy times are of the same order as the size of the active population. Mutations appear as Poisson processes on the active lineages, and potentially at reduced rate also on the dormant lineages. The presence of 'dormant' lineages leads to qualitatively altered times to the most recent common ancestor and non-classical patterns of genetic diversity. To illustrate this we provide a Wright-Fisher model with seed bank component and mutation, motivated from recent models of microbial dormancy, whose genealogy can be described by the seed bank coalescent. Based on our coalescent model, we derive recursions for the expectation and variance of the time to most recent common ancestor, number of segregating sites, pairwise differences, and singletons. The effect of a seed bank on the expected site-frequency spectrum is also investigated using simulations. Our results indicate that the presence of a large seed bank considerably alters the distribution of the site-frequency spectrum. Thus, one should be able to detect the presence of a large seed bank in genetic data.

Summer Semester 2015

01.06.2015

Maria Anisimova-"Disentangling tandem repeats with computational prediction"

ETH Zürich, Switzerland

Abstract: Tandem repeats (TRs) are frequently observed in genomes across all domains of life. Evidence suggests that some TRs are crucial for proteins with fundamental biological functions, and can be associated with virulence, resistance and infectious/ neurodegenerative diseases. Genome-scale systematic studies of TRs have the potential to unveil core mechanisms governing TR evolution and TR roles in shaping genomes. However, TR-related studies are often non-trivial due to heterogeneous and sometimes fast evolving TR regions. In this talk I will discuss our recent contributions to computational and statistical approaches for TR annotation, TR-aware sequence alignment, and phylogenetic analyses of TR conservation. All these methods explicitly rely on the evolutionary definition of a tandem repeat as a sequence of adjacent repeat units stemming from a common ancestor. The discussed work has a focus on protein TRs, yet is generally applicable to nucleic acid TRs, sharing similar features.

08.06.2015

Frank Oliver Glöckner - Environmental Bioinformatics - with a focus on “Marine”

Max Planck Institute for Marine Microbiology & Jacobs University Bremen gGmbH

Abstract: Investigations in molecular biology have transitioned from single experiments to high-throughput “big data” endeavours spearheaded by genomic sciences. New integrative approaches are needed to transform the wealth of environmental sequences and contextual (meta)data into biological knowledge on microbial diversity and function.
The talk will elaborate on the goals and perspectives of bioinformatics capacity building in the EU 7FP “Ocean of Tomorrow Project” Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology, www.microb3.eu). It will explain the concept, standards and implementation of the community driven Ocean Sampling Day (OSD, www.oceansamplingday.org). The first OSD took place worldwide on 21st of June (summer solstice) 2014, mobilizing over 190 marine sampling sites. The next OSD is planned for June 2015 with a strong involvement of citizen scientists (www.my-osd.org). These cumulative samples, fixed in time and space supplemented with a broad set of geo-referenced environmental parameters will provide new insights into the relationships between organisms, their genomic repertoire, and the environment surrounding them. Since most of the sampling sites are coastal, OSD provides the unique opportunity to study the effect of human pressure on the unseen majority in our ocean.

22.06.2015

Jose Jimenez-Gomez- "Natural variation in circadian rhythms suggests effect of domestication on the circadian clock of tomato"

MPI Cologne, Germany

Abstract: The circadian clock controls many important aspects of plant physiology and development, including several traits of agronomical significance. Variation in circadian rhythms appears to be important for adaptation to specific environments. Domestication in tomato (Solanum lycopersicum) has drastically affected its geographical distribution and many characters of agricultural interest. I will show our work using tomato as a model system to study the importance of circadian rhythms during domestication.

29.06.2015

Julian Glos - "Species and functional diversity of amphibian assemblages in a rainforest in Madagascar"

University of Hamburg, Germany

Abstract: Functional diversity illustrates the range of ecological functions in a community, and it allows revealing the appearance of functional redundancy in communities and processes of community assembly. Functional redundancy illustrates the overlap in ecological functions of community members which may be an indicator of community resilience. I will present patterns of species richness and species turnover, and of functional diversity and functional redundancy, in tadpole and frog communities in a rainforest of Eastern Madagascar. This habitat harbours one of the world's most species-rich amphibian communities. It is characterized by environmental changes and steep environmental gradients that are due to either natural changes (i.e., between two seasons) or anthropogenic impact (i.e., habitat fragmentation, disturbances). Accordingly, I will show how the patterns of species and functional diversity in amphibian assemblages vary along these environmental changes.

06.07.2015

Ivan Gomez-Mestre- "Micro- and Macroevolution of Life Histories in Anurans:
Can Developmental Plasticity help Connect the Dots?"

Donana Biological Station, Spain

Abstract: Developmental plasticity allows populations to withstand rapid environmental changes and confers an overall faster rate of adaptation. However, selection in stable environments can result in genetic assimilation, potentially leading to trait divergence and species diversification. In that case, we would expect ancestral plasticity to mirror differences among taxa. Thus in that light, we are studying mechanisms of plasticity behind the evolutionary divergence of spadefoot toads. By studying the mechanisms of developmental acceleration in response to pond drying and comparing them across species, we have found that Pelobates tadpoles, which reflect the ancestral state of the group, increase their metabolic rate, and thyroid hormone and corticosterone concentrations in response to decreased water levels. All these parameters, however, seem to have been canalized in the descendant-state group Scaphiopus, leading support to the hypothesis of genetic accommodation.

13.07.2015

Holger Goerlitz - "Auditory interactions in the night sky: bats, moths, and global warming"

MPI Seewiesen

Abstract: Echolocating bats and moths with bat-detecting ears interact in a predator-prey-relationship that is solely based on acoustic information. Bats use echolocation, an active-sensing strategy, to detect their insect prey. In turn, ears and evasive flight evolved in many insect taxa to prevent being captured by bats. We study these auditory-guided interactions between echolocating bats and eared moths in the field and lab, using neurophysiological recordings from moth ears, molecular diet analysis, flight path tracking in the field and acoustic modelling. This talk will present auditory adaptations in the prey to their sympatric predator ensemble, counter-measures in predators to avoid being heard by the prey, and additionally how external factors such as global warming might affect auditory interactions.

Winter Semester 2014/15

13.10.2014

Clelia Gasparini - "Sex in the tank: what guppies can tell us about sexual selection and sexual conflict before and after mating"

The University of Western Australia, Perth, Australia

Abstract: Sex is rarely a harmonious process, and males and females often have conflicting evolutionary interests over reproduction. In most species such conflict rarely ends at mating because females typically mate with multiple males (polyandry), thus extending the opportunities for sexual selection to include sperm competition (where ejaculates from different males compete for fertilization) and cryptic female choice (where females moderate this competition). Using a small livebearing fish, the guppy, I study pre- and post- copulatory sexual selection to unravel strategies used by males and females to maximize their own reproductive success. In this seminar I will present results from my ongoing research that explores how these reproductive conflicts of interest play out across the sexual selection continuum (pre- and postcopulatory sexual selection). Insights from this work reveal how the females’ choice of attractive mates can be undermined by male behavioural strategies, how males make faster sperm to win the (sperm competition) race while ‘fussy’ females potentially counteract these effects by slowing them down, and ultimately why choosing the most popular male may yet pay off for females.

27.10.2014

Robert Ptacnik - "Fresh and salty: Spatial pattern in plankton diversity along natural stress gradients"

WasserCluster Lunz, Austria

Abstract: Salinity represents about the strongest selective gradient in aquatic habitats, which is reflected in the distinctive biotas of freshwater and marine habitats. In estuaries, the transition from freshwater to marine conditions is populated by a few tolerant freshwater and marine taxa forming opposing ends of the gradient, plus a limited number of specialized brackish taxa. The brackish taxa, however, do not compensate for the species loss of other taxa. As a result, communities of most higher taxa exhibit a characteristic diversity minimum at intermediate salinities ('Artenminimum', Remane 1934).

This relationship can be understood regarding the limited connectivity among estuaries. It implies that the total species pool available for colonizing this intermediate zone is considerably smaller than the species pools populating its end points. Microscopic organisms are assumed to be highly mobile and at the same time expected to evolve rapidly. Salinity gradients therefore represent a test ground for the assumptions that biogeography of microbes differs fundamentally from higher organisms. I will show data on the spatial pattern of phytoplankton diversity in the Baltic Sea with a focus on the species pools and their origin that populate different salinities in the Baltic Sea.

03.11.2014

Michal Kucera - "Cryptic diversity in marine plankton"

MARUM & Fachbereich Geowissenschaften, University of Bremen, Germany

Abstract: Species of marine eukaryotic plankton have numerically enormous populations, exposed to constant passive dispersal by currents that is not limited by physical barrier. Intuitively, these factors can be expected to inhibit speciation. Yet, marine plankton is highly diverse and, paradoxically, genetic fingerprinting has revealed that its biological diversity has been severely underestimated due to the abundance of cryptic speciation. Our research seeks to understand the nature and origin of cryptic species in the plankton and unravel the consequences for the study of biodiversity and evolution in the largest environment on the surface of the Earth. We use planktonic foraminifera, which produce one of the best fossil records available to study, allowing us to combine present-day phylogeography with the evolutionary history of the group. I will present the results from extensive global surveys of single-cell sequence data in three clades that revealed unexpected patterns of geographical and ecological structure in what previously seemed to be cosmopolitan species. Using well constrained molecular clocks, I will show that cryptic divergences are ancient and their existence reflects a fundamental de-coupling of morphological evolution from genetic divergence.

10.11.2014

Marie Manceau - "Morphogenesis and Molecular Regulation of Colour Patterning in Natural Populations"

College de France, Paris, France

Abstract: The distribution of color across the body (i.e., color pattern) is a crucial morphological trait involved in survival and reproductive success which varies tremendously both within and between species. Despite their ecological importance, the genetic and developmental mechanisms responsible for the formation and variation of naturally-occurring color patterns have remained a black box. We showed that in deer mice (genus Peromyscus), the formation of a simple bicolor pattern typical of most vertebrates relies on the establishment of an embryonic “pre-pattern” (i.e., the spatial restriction of pigmentation genes) causing regional differences in pigment cell behavior. Moreover, we showed that large adaptive changes in the adult color pattern seen in a derived Peromyscus population are provoked by small accumulating changes in the pre-pattern. These findings laid the groundwork for studying (1) the embryonic origin of pre-patterns in the skin, (2) the molecular control of their formation and (3) the genetic basis of their evolution in other vertebrates groups. To this end, we propose to use analyses of gene expression and function in natural populations of birds displaying a vast array of skin patterns.

17.11.2014

Julien Gagneur - "Insights from genetics of gene expression into mutational robustness and causal inference."

LMU Genzentrum, Munich, Germany

Abstract: I will present two of our systems genetics studies.
1. Mechanisms conferring robustness against regulatory variants have been controversial. Previous data suggested widespread buffering of RNA misexpression on protein levels during translation. We do not find evidence that translational buffering is common. Instead, we find extensive buffering at the level of RNA expression, exerted through negative feedback regulation acting in trans, which reduces the effect of regulatory variants on gene expression.

2. We show how non-additive effects between genotype and environment can be exploited for causal inference in molecular networks. Using genome-wide perturbation assays in yeast, we experimentally demonstrate the validity of the approach.

01.12.2014

Andrea Betancourt - "Transposable element dynamics in Drosophila”

VedMedUni Vienna, Austria

Abstract: Transposable elements are genomic parasites with an evolutionary strategy of increasing their copy number; the success of this strategy can be seen in many eukaryotic genomes, which contain large fractions of transposon derived DNA. Recently, we have begun to acquire an in-depth picture of the population dynamics of transposable elements in Drosophila, with both bursts of transposition and purifying selection against new insertions appear to affect population frequencies of insertions. However, another important process in transposable element evolution -- horizontal transmission between species -- is less wellunderstood. The classic example of a horizontally transmitted element is that of the P-element in D. melanogaster. Recently, we have found that the P-element appears to have recently spread from D. melanogaster into a sister species, D. simulans. P-element appears to have spread quickly in D. simulans, with strains from the same geographic region showing P-element to have increased from low to high frequency within a decade.

19.01.2015

Brian Hollis - "Adaptation and antagonism in populations evolving without sexual selection"

University of Lausanne, Switzerland

Abstract: Sexual selection may accelerate adaptation, as "good genes" theory predicts, or act as a load upon populations because of conflict between the sexes. We investigate these possibilities with fly populations that have evolved in the laboratory for over 150 generations either with sexual selection (a polygamous mating system) or without sexual selection (a monogamous mating system). Monogamous populations benefit from the evolution of reduced sexually antagonistic interactions, which can be detected in the female post-mating transcriptional response. Male selection pressures are also greatly relaxed under monogamy. This has resulted in the evolution of feminized patterns of gene expression, suggesting strong constraints on sexually dimorphic gene expression in nature.

26.01.2015

Wolfgang Stephan - "Population genomics of adaptation in Drosophila melanogaster"

LMU-Munich, Germany

Abstract: In several organisms (whose genome has been sequenced) scans of DNA sequence variation have been carried out to elucidate the recent demographic and adaptive histories of these species. Using selective sweeps, it is possible to identify adaptive events in the genome. I will present results from our work on Drosophila melanogaster. I show that selective sweep analysis can be used to accurately map targets of positive selection in the genome. Furthermore, I will discuss whether selective sweep mapping can be combined with QTL mapping to determine the phenotype selection has been operating on. Two case studies will be highlighted: (1) the divergence of the tandemly duplicated polyhomeotic (ph) genes under positive selection, and (2) the localization of candidate genes for cold tolerance.

Summer Semester 2014

14.07.2014

Miltos Tsiantis - "From genes to geometry: towards understanding development and diversification of leaf form"

MPI for Plant Breeding Research, Cologne, Germany

Abstract: A key challenge in biology is to understand how diversity in organismal form is generated. Genetic analyses in model systems have identified key regulators that sculpt the body plans of metazoa and seed plants. However, less is known about how the action of such regulators produces particular organ shapes, or how the balance of conservation versus divergence of such form regulating pathways generated the tremendous morphological diversity of multicellular eukaryotes. One impediment to answering these questions is the relative paucity of experimental platforms where genetic tools can be utilized to unambiguously study morphogenesis and its evolution in a genome-wide, unbiased fashion. To circumvent this problem we developed the Arabidopsis thaliana relative Cardamine hirsuta into a versatile system for studying morphological evolution. We aim to understand the molecular mechanisms through which leaf morphology evolved in these species, resulting in simple, undivided leaves in A. thaliana and dissected leaves with distinct leaflets in C. hirsuta. This presentation will discuss our progress towards understanding the genetic pathways that specify dissected versus entire leaf shapes and that regulate the number, position and timing of leaflet production.

30.06.2014

Jonathan Jeschke - "What we know and don’t know about invasive species and other novel organisms"

Technical University of Munich, Germany

Abstract: The talk will consist of two parts, the first one focusing on invasive species and the second one on other types of novel organisms, e.g. range-expanding species, GMOs, or emerging pathogens. I will start with an overview of current understanding, and lack thereof, about invasive species. The focus will be on animals, but comparisons to plants and other organisms will be made as well. I will address the following fundamental questions about biological invasions: (1) How many species become invasive in a given region? (2) Which ecosystems are especially susceptible to invaders? And (3) What are the long-term effects of invaders? In the second part of the talk, I will present a framework that compares invasive species with other types of novel organisms, e.g. emerging pathogens, and allows knowledge transfer among researchers and managers working on different novel organisms.

16.06.2014

Gerald Wilkinson - "Sexual selection, genomic conflict and speciation in stalk-eyed flies"

University of Maryland, USA, and Wissenschaftskolleg zu Berlin, Germany

Abstract: Speciation occurs when isolated populations diverge sufficiently to cause reproductive isolation. The processes that drive such divergence remain poorly understood. One possibility is sexual selection, which can cause rapid evolution of traits that influence precopulatory or postcopulatory success, but should only cause divergence if populations exhibit differences in mating preferences. An alternative is some type of genomic conflict, such as that responsible for biased transmission of X or Y-bearing sperm, that leads to an arms race between driving and suppressing elements. If coevolution among elements proceeds independently in isolated populations, then heterogametic hybrid sterility or inviability could occur. In this talk, I will present results from a series of studies on stalk-eyed flies that show how sexual selection and genomic conflict operate and interact to cause rapid evolution of reproductive isolation among allopatric populations in southeast Asia. I will also discuss recent genome and transcriptome studies that provide insight into the genetic causes and consequences of the ongoing sex chromosome conflict. The results suggest the genomic landscape, especially of the sex chromosomes, is remarkably dynamic in this extraordinary group of flies.

02.06.2014

Gerald Schneeweiss - "Phylogeny and evolution of the non-photosynthetic parasitic broomrapes (Orobanchaceae)"

University of Vienna, Austria

Abstract: A hallmark of plants is their ability to utilize light as the primary energy source for producing complex organic compounds. Some plants, however, developed deviating nutritional modes including parasitism, which within angiosperms has independently evolved about twelve times. A major lineage of parasitic angiosperms is the family Orobanchaceae, containing c. 2000 species, where the full range of nutritional modes from non-parasitic via facultative and obligate photosynthetic parasites (hemiparasites) to non-photosynthetic parasites (holoparasites) is realized, rendering Orobanchaceae the model group for studying genetic, genomic, physiological and morphological adaptations and changes associated with the shift to and the intensification of parasitism. Here, I will focus on the exclusively holoparasitic clade containing Orobanche and related genera to address phylogenetic-taxonomic and evolutionary questions with respect to, for instance, genome or life history evolution.

26.05.2014

Christian Sturmbauer - "Adaptive evolution and phenotypic plasticity in the context of adaptive radiation"

Department of Zoology, University of Graz, Graz, Austria

Abstract: Allopatric speciation often yields ecologically equivalent sister species, so that their secondary admixis enforces competition under sympatry. The rocky shores of Lake Tanganyika harbor more than 100 distinct populations and sister species of the cichlid genus Tropheus, but only some are sympatric. When alone Tropheus occupies a relatively broad depth zone, but in sympatry fish segregate by depth. To assess the effects of competition we studied the partial co-occurrence of Tropheus moorii “Kaiser” and “Kirschfleck” with Tropheus polli along a section of the central eastern shores of the lake. Hybridization experiments demonstrated that some observed differences between Tropheus “Kaiser” living alone and in sympatry to T. polli have a genetic basis despite large-scale phenotypic plasticity. Using geometric morphometrics and neutral genetic markers, we investigated whether sympatric populations differ consistently in body shape from populations living alone and if the differences are adaptive. We found significant differences in mean shape between non-sympatric and sympatric populations, whereas all sympatric populations of both color morphs clustered together in shape space. Sympatric populations had a relatively smaller head, smaller eyes, and a more anterior insertion of the pectoral fin than non-sympatric populations. Genetically, however, non-sympatric and sympatric “Kaiser” populations clustered together to the exclusion of “Kirschfleck”. Genetic distances, but not morphological distances, were correlated with geographic distances. Within- and between-population covariance matrices for T. moorii populations deviated from proportionality. We conclude that natural selection acts on both phenotypic plasticity and heritable traits, and that both factors contribute to the observed shape differences. The consistency of the pattern in five populations suggests ecological character displacement.

12.05.2014

Fabian Staubach - "Approaches to better understand the role of microbes in the adaptation of metazoans"

University of Freiburg, Germany

Abstract: Almost all organisms on earth are associated with microorganisms. These microorganisms are important for the evolution of their hosts. However, the role they play for the evolution of their hosts can be very different. On the one hand, disease causing pathogens can exert strong selection pressures on the host that are reflected by fast evolution of host immune genes. On the other hand, microbes that are beneficial for the host have facilitated major adaptations of their host. A prominent example of an adaptation through microorganisms is the protistan microbiota in the gut of termites that facilitates the digestion of wood. I will present approaches to better understand the role of microbes in adaptation using Drosophila and termites as models.

05.05.2014

Gerton Lunter - "Inferring demography from whole-genome data"

University of Oxford, UK

Abstract: Genetic data is informative about demography, and holds for instance evidence of past population bottlenecks, admixture and migration. Inferring these from genetic data is however not trivial. Most existing approaches rely on summary statistics, such as site-frequency spectra. More recently, approaches that directly model the process of recombination and coalescence along the sequence have succeeded in inferring past population changes from a single diploid genome. However, extending this approach to multiple samples is not straightforward.

In the talk I will discuss an approach we have been taken, using a fairly recent statistical technique known as particle filters. This approach has the promise to scale to high-dimensional models, and is well suited to this particular inference problem.

28.04.2014

Detlev Arendt - "Evolution of the central nervous system in Bilateria"

EMBL Heidelberg, Germany

Abstract: We are intrigued by one of the great remaining mysteries in animal evolution: how did our central nervous system (CNS) come into existence? What did it look like at first and how did it function? We are especially interested in the CNS of an extinct animal known as Urbilateria, the last common ancestor of humans, flies and most other ‘higher’ animals that live today, which lived some 600 million years ago in the ocean. Our lab has chosen to investigate a new molecular animal model, the marine annelid Platynereis dumerilii. As a ‘living fossil’, Platynereis represents an ideal connecting link between vertebrates and the fast evolving protostome models, Drosophila and Caenorhabditis. Genomic resources and molecular techniques have been generated that make it a model marine invertebrate for ocean biology and for organismal systems biology. As characteristic for the Platynereis life cycle with different stages exploring different ecological niches, environmental influences impact directly on the organismal state (eco-devo) or are sensed via the nervous system (organismal neurobiology) and are reflected by the variation on genome, transcriptome or any other level of the cellome.

14.04.2014

Miguel Gallach - "Recurrent turnover of chromosome-specific satellites in Drosophila"

CIBIV-Vienna, Austria

Abstract: Non-coding repetitive DNA has the ability to adopt specific folding structures that may help cells identify chromosomes. In addition, repetitive DNA elements have also become a major interest among evolutionary biologists since species-specific interactions between chromatin remodeling proteins and repetitive DNA elements are disrupted in hybrids. Remarkably, in Drosophila, the X and dot chromosomes are identified by chromosome-specific binding proteins and they are particularly involved in genetic incompatibilities between closely related species. I found that these two chromosomes are overpopulated by certain repetitive elements that undergo recurrent turnover in Drosophila species. The biology and evolutionary patterns of the characterized satellites suggest that they provide both chromosomes with some kind of structural identity and are exposed to natural selection. The rapid satellite turnover fits some speciation models and may explain why these two chromosomes are typically involved in hybrid incompatibilities

Winter Semester 2013/14

03.02.2014

John Colbourne - "How Genomic Responses to the Environment Vary"

Environmental Genomics Group, School of Biosciences, University of Birmingham, UK

Abstract: Daphnia, or the water flea, is a sentinel species of freshwater ecosystems. Their populations are defined by the boundaries of ponds and lakes, are sensitive to modern toxicants in the environment, and thus are used to assess the ecological impact of environmental change. Their short generation time, large brood sizes, and ease of laboratory and field manipulation have assured Daphnia’s importance for setting regulatory standards by environmental protection agencies, testing chemical safety, monitoring water quality, and as a model for environmental genomics research. In this study, we take advantage of the animal’s clonality and mature genomics tools to dissect the sources of gene expression variation in the stress response of genetic isolates to six environmentally relevant pollutants, and their binary mixtures. One isolate originates from a natural population that has faced severe chemical challenges for over a century of industrial iron/ore smelting and thus demonstrates evolved tolerance to toxic levels of certain metals. Another isolate originates from a population that has no history of chemical stress and is clearly harmed by metal exposure. By interrogating differential expression of 31,000 annotated genes from 50 comparisons across conditions and between isolates, the current study provides new insights into the functional interactions among genes and environment.

The research was conducted during hands-on training in “Environmental Genomics” – an annual summer course offered at the Mount Desert Island Biological Laboratory.

27.01.2014

Alexandre Courtiol - "What can humans tell us about mate choice in other species?"

Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany

Summary: My talk aims at demonstrating that anthropocentrism is a flaw that can be turned into an asset. Keeping humans in mind can indeed help us to better understand animal behaviour and working on humans allows researcher to gather data that are difficult to collect in other organisms. I will rely on the work I performed on mate choice in humans to illustrate this claim. I will show you how some trivial observations of our everyday life has lead me to rethink the theory of sexual selection. In short, I will explain why humans could be considered as a model organism for the study of mate choice.

Winter Semester 2013/14

09.09.2013

Masaru Iizuka - "A Model of Compensatory Molecular Evolution with Indirect Compensation"

Division of Mathematics, Kyushu Dental University, Japan

Abstract: Consider two sites under compensatory fitness interaction. If there is an extra pair of sites that can reduce the deleterious effects of single mutants at the original sites, this reduction is called indirect compensation. We develop a mathematical model of indirect compensation and discuss the effects of indirect compensation on the rate of compensatory molecular evolution.

19.09.2013

Rosemary G. Gillespie - "Community assembly through adaptive radiation: Spiders on islands"

University Of California, Berkeley, USA

Abstract: Remote islands are heralded as “natural laboratories”, with communities largely comprising species that have evolved within the islands as a result of adaptive radiation. I have been examining commonalities underlying patterns of adaptive radiation and how communities are filled in such situations, focusing on spiders in conjunction with other lineages of both animals and plants. Here, I examine patterns of morphological and ecological differentiation across the Pacific and how diversity can arise from a small sample of colonists. Specific topics will include: (1) Patterns of diversification and species accumulation within an adaptive radiation. What are the relative roles of colonization or dispersal versus parallel or convergent evolution and associated niche shifts, in shaping ecologically similar sets of species on different islands of the Hawaiian chain? (2) Integrating population genetics and macroecological metrics to assess biodiversity dynamics. How can we use the dynamic geology of the Hawaiian Islands to understand feedbacks between adaptation, population divergence, and associated community succession? Overall, this research promises insights into the interplay between selection and the biotic environment in the evolution of species within a community, and the nature and timing of species accumulation and equilibrium.

21.10.2013

Ines Hellmann - "Evidence for local selection in northern Swedish Arabidopsis thaliana"

Section of Anthropology and Human Biology, LMU Munich, Germany

Abstract: Arabidopsis thaliana is the model organism for plant genetics and that is at least partially due to the wealth in natural phenotypic variation. Moreover, there is accumulating evidence that some of the phenotypes represent adaptations to local environments. Keeping this in mind, the lack of genetic evidence for positive selection is surprising. Here, we investigate signatures of selection more closely in southern and northern Swedish A. thaliana. After characterizing the demographic history of Swedish A. thaliana, we find evidence for hard selective sweeps in the northern and southern population, although selection in the south appears to be weaker. Further, characterizing synonymous and non-synonymous polymorphisms suggest that this difference in selection strength is due to a more heterogeneous environment in the south.

04.11.2013

Kavita Jain - "Fixation of beneficial mutations in finite asexual populations"

J Nehru Centre for Advanced Scientific Research, Bangalore, India

Abstract: I will discuss the adaptive evolution of finite asexual populations on simple and complex fitness landscapes.
In the first part of the talk, I will describe a model in which deleterious and beneficial back mutations occur and fitnesses are multiplicative. As a result of reversible mutations, the population reaches an equilibrium at large times and I will explain how the number of deleterious mutations in the stationary state depend on various population genetic parameters. Our results are relevant to an understanding of the bias in codon usage and halting the Muller's ratchet.

In the second part of the talk, I will describe the adaptive walk performed by a population under strong selection-weak mutation conditions on a fitness landscape with many local fitness peaks. We find a simple relationship between the trends in the fitness gain during successive steps of the adaptive walk and the extreme value domain of the distribution of beneficial fitness effects (DBFE). This result may be useful in the experimental determination of DBFE using adaptation dynamics .

18.11.2013

Nicolas Gompel - "The genetics underlying the emergence and diversification of a wing decoration”

Evolutionary Ecology, LMU Munich, Germany

Abstract: The typical pattern of morphological evolution associated with the radiation of a group of related species is the emergence of a novel trait and its subsequent diversification. From butterfly eyespots and their various colorful rings to the diversity of shapes assumed by vertebrate teeth, seashells or horn beetles, this pattern of emergence-diversification holds for countless characters across most animal groups. Yet the genetic mechanisms associated with these two evolutionary steps are poorly characterized. We're studying the evolution of wing pigmentation patterns in flies to address from a gene regulatory perspective how morphological novelties (rarely) emerge and how they (often) diversify. We're also studying the function of wing pigmentation patterns in mating behavior to identify the possible selective mechanisms underlying the evolution of this morphological trait.

25.11. 2013

Francesco Catania - "Networks, competition, trade-offs, and the evolution of genes in eukaryotes"

Institute for Evolution and Biodiversity (IEB), University of Münster, Germany

Abstract: The instructions for the synthesis of proteins are stored within genes in sequences called exons. In eukaryotes, genes contain additional DNA sequences, known as spliceosomal introns, which neither inform nor regulate the assemblage of amino acid chains. Why do eukaryotic genes have introns, and where do introns come from are still open questions in biology. In this talk, I will revisit one mechanism for the origin of spliceosomal introns, the intronization of exonic sequences, which describes the physical establishment and distribution of spliceosomal introns along transcripts. I will then discuss some ramifications that result when the model is applied to a scenario that accounts for 1) the extensive network of interactions between mRNA-associated processes and 2) the antagonistic relationships between molecules mediating the co-transcriptional processes of mRNA splicing and mRNA 3-end formation. The simple and logical connections that result from this molecular scenario suggest that a number of gene properties may be the byproduct of structural molecular constraints rather than adaptive selection.

09.12.2013

Philipp Assmy - "Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current"

Norwegian Polar Institute, Tromsoe, Norway

Abstract: Diatoms of the iron-replete continental margins and North Atlantic are key exporters of organic carbon. In contrast, diatoms of the iron-limited Antarctic Circumpolar Current sequester silicon, but comparatively little carbon, in the underlying deep ocean and sediments. Because the Southern Ocean is the major hub of oceanic nutrient distribution, selective silicon sequestration there limits diatom blooms elsewhere and consequently the biotic carbon sequestration potential of the entire ocean. We investigated this paradox in an in situ iron fertilization experiment by comparing accumulation and sinking of diatom populations inside and outside the iron-fertilized patch over 5 weeks. A bloom comprising various thin- and thick-shelled diatom species developed inside the patch despite the presence of large grazer populations. After the third week, most of the thinner-shelled diatom species underwent mass mortality, formed large, mucous aggregates, and sank out en masse (carbon sinkers). In contrast, thicker-shelled species, in particular Fragilariopsis kerguelensis, persisted in the surface layers, sank mainly empty shells continuously, and reduced silicate concentrations to similar levels both inside and outside the patch (silica sinkers). These patterns imply that thick-shelled, hence grazer-protected, diatom species evolved in response to heavy copepod grazing pressure in the presence of an abundant silicate supply. The ecology of these silica-sinking species decouples silicon and carbon cycles in the iron-limited Southern Ocean, whereas carbon-sinking species, when stimulated by iron fertilization, export more carbon per silicon. Our results suggest that large-scale iron fertilization of the silicate-rich Southern Ocean will not change silicon sequestration but will add carbon to the sinking silica flux. Significance statement: Silica-shelled diatoms dominate marine phytoplankton blooms and play a key role in ocean ecology and the global carbon cycle. I will show how differences in ecological traits of dominant Southern Ocean diatom species, observed during the in situ European Iron Fertilization Experiment (EIFEX), can influence ocean carbon and silicon cycles. I argue that the ecology of thick-shelled diatom species, selected for by heavy copepod grazing, sequesters silicon relative to other nutrients in the deep Southern Ocean and underlying sediments to the detriment of diatom growth elsewhere. This evolutionary arms race provides a framework to link ecology with biogeochemistry of the ocean.

16.12.2013

Rita Adrian - "Windows of opportunity: The role of extremes and thresholds in ecological research"

IGB Berlin, Germany

Abstract: We use Long-Term Ecological Research to understand lake ecosystem dynamics with a focus on plankton communities. The value of long-term ecological research is that the observed pattern and temporal dynamics incorporate the entire complexity of internal and external driving forces, which cannot by mimicked in experimental or modelling exercises. I will present a couple of case studies showing responses of lakes to environmental change such as climate warming. The case studies encompass the role of critical time windows, the quantification of critical thresholds, the impact of heat wave events, etc. Moreover, I will provide an example documenting- how long-term ecological research can help to test and combine ecological theory – and by that help to understand the complex nature of driving forces.

Summer Semester 2013

29.04.2013

Julia Schroeder - "Indirect genetic effects through social interactions - a case study"

Max Planck Institute for Ornithology, Seewiesen, Germany

Abstract: The social environment - the presence and behaviour of conspecifics - can influence the expression of phenotypes i.e., individuals other than the one expressing the focal trait can explain some of the phenotypic variation. The genetic part of this indirect effect represents an indirect genetic effect (IGE). Not accounting for IGEs can considerably under- or over-estimate the total heritable variation available for selection to act on, and thus predict misleading evolutionary trajectories. Yet, empirical studies on wild populations often ignore IGEs. I will present a quantitative genetic analysis of biparental care in a wild bird population. My results suggests that the female trait could evolve through indirect selection by her mating partner, which most theoretical models explaining the evolution of biparental care do not assume. Notably, the within-individual repeatability of female parental care was lower than the total heritable variation. This shows that the assumption that repeatability is the upper limit of heritability should be used cautiously when applying to socially interactive traits, and highlights the importance of accounting for social effects.

06.05.2013

Daniel Wegmann - "Model based inference of evolutionary histories"

Swiss Federal Institute of Technology (EPFL) Lausanne, Switzerland

Abstract: A detailed understanding of the evolutionary history of a species or population is crucial when identifying the targets of selection, inferring modes and tempo of speciation or designing appropriate management efforts in conservation. However, inferring evolutionary histories has been proven difficult, mainly because neutral processes are extremely stochastic and analytical solutions are difficult to obtain expect for the most simple models. This situation only recently changed with the advent of ever more powerful sequencing technologies allowing us to generate enormous data sets to overcome the stochastic nature of neutral processes, and numerical approaches that allow us to side-step or facilitate the calculation of likelihood functions. In this talk, I will make the case for model based inference in an evolutionary context and illustrate various numerical strategies, focusing on a composite likelihood approach and, in particular, Approximate Bayesian Computation (ABC). I will then discuss ideas on how to render ABC fit for complex models and large data sets, and illustrate them by inferring aspects of the evolutionary history of humans, rose finches and the clade of all carnivora.

13.05.2013

Wolfgang Weisser - "Ten years of the Jena Biodiversity Experiment – a selective review"

Department of Ecology and Ecosystem Management, Technische Universität München & The Jena Experiment Consortium, Germany

Abstract: The Jena Experiment was set up in 2002 to investigate the effects of plant diversity on closed element cycling and trophic interactions and presents today one of the largest and longest-running functional biodiversity experiments. In the talk I will review the results of the almost 10 years of research in the experiment. I will review which ecosystem variables are more strongly affected by biodiversity and which ones are less affected, including measurements of element cycling and biotic interactions. A main conclusion that emerges from the work is that the future of biodiversity research lies in understanding why the magnitude of biodiversity effects differs between processes. Future studies need to concentrate on the identification of the mechanisms underlying the observed patterns, in particular on how ecosystem variables are driven by species interactions and how these interactions are affected by diversity.

27.05. 2013

Michael Monaghan – "Large-scale evolution and local adaptation in aquatic insects"

Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Germany

Abstract: Large-scale sequencing projects of communities in nature (DNA barcoding, next-generation "meta-barcoding") are increasingly applied to species delineation and identification in biodiversity research and bio-monitoring applications. These same methods also provide novel insights into large-scale patterns of evolution across taxa, which in turn lead to interesting interface of basic and applied biodiversity research is whether and how the nature of the evolutionary process makes the observed patterns scale-dependent. Here I present ongoing work on how the evolutionary process makes the application of sequence-based inventorying scale-dependent for a group of aquatic insects in Europe. In contrast to this large-scale work (100s - 1000s km) using neutral markers, ongoing work in natural populations using genome scans (AFLP) shows consistent patterns of local adaptation (1-10 km) in aquatic insect populations in nature.

03.06.2013

Piet Spaak - "Daphnia hybridization in peri-alpine lakes over space and time"

EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Switzerland

Abstract: The three Daphnia species of the D. longispina complex (D. galeata, D. longispina and D. cucullata) and their hybrids can be found in lakes all over Europe. Many factors (e.g. food quality and quantity, predation, diseases, competition) have been studied to explain why parentals and hybrids co-occur. We reconstructed some of the Daphnia populations North of the Alps over time, using sediment cores, and showed that eutrophication is an important factor in determining the composition of Daphnia populations over time.
To study on a spatial scale the composition of Daphnia populations we surveyed Daphnia populations north and south of the Swiss Alps. We found that Lakes North of the Alps were invaded with one species (D. galeata) and hypothesize that lakes south of the Alps were invaded with D. longispina. A first life history experiment shows some evidence for this hypothesis. Further, testing of this hypothesis needs to come from sediment cores from lakes from the south side of the alps. I will present recent data about these studies.

10.06.2013

Urban Friberg - "Genetics of sexual dimorphism"

Evolutionary Biology Centre, Uppsala University, Sweden

Abstract: Evolution of sexual dimorphism (SD) is a paradox. On the one hand it shouldbe constrained, because it is restricted to occur only through geneexpression and because it relies on gene expression having a sex-specificgenetic architecture. On the other hand SD is common and SD traits are amongthose that evolve the fastest. How is this possible? Is evolution of SDreally constrained, or is SD evolving rapidly despite constraints? Previousstudies have given inconsistent answers to this question, when applied totraits at a high level of phenotypic organization (morphological, behavioraland physiological). We addressed this question at the lowest level ofphenotypic organization – gene expression – and found substantial evidencefor constraints hindering evolution of SD in the Drosophila genus. I willpresent results from this study, as well as preliminary data which indicatesthat the X-chromosome may play a key role in mediating evolution of SD. Iwill also present data from a study on the genetics of SD for lifespan inDrosophila. Lifespan turns out to have a surprisingly decoupled geneticarchitecture between the sexes, which results in large differences in theheritability of this trait within and across the sexes and points to thatdisease genetics in fruit flies is vastly different in males and females.

17.06.2013

Volker Sommer - "Neither Good Nor Bad. Morality And Evolution"

Department of Anthropology, University College London, UK

Abstract: Many people judge a behaviour as morally wrong, because it is allegedly "unnatural". A prominent example is the condemnation of homosexual conduct as directed "against nature". Such arguments are typically ill-informed. For example, same-sex sexual contacts are quite common in non-human animals. Still, this doesn't imply that one should condone such behaviour either. Virtually all conceivable human behaviours are also shown by animals - be it cannibalism, cooperation, incest, infant-killing, empathy, masturbation, food-sharing, sex with immatures, polyandry, sacrifice for one's group or war. Whether or not we judge such traits as reprehensible, acceptable or desirable, depends on our cultural background. Nevertheless, solid natural history can certainly be helpful in debates about how societal norms should be constructed.

24.06.2013

Vasilis Promponas - "Genome evolution and large-scale protein function prediction"

Department of Biological Sciences, University of Cyprus, Cyprus

Abstract: Since the first complete genome sequences of free-living organisms became available, a number of computational methods –collectively known as "genome-aware methods"– were proposed for the inference of protein function, structure and interactions. Such methods (including gene clusters, gene fusions and phylogenetic profiles) have proved invaluable for the in silico functional characterization of proteins, especially in cases where no identifiable sequence similarity exists to proteins of known function.

In this presentation, I will describe the basic principles behind these genome-aware methods, using as examples applications to real-world complete genome data. I will try to highlight specific success stories and pitfalls, elaborating on how genome-aware methods (in particular gene-fusion analysis) are confounded by genome sequence quality, including gene prediction accuracy and assembly validation. Finally, I will conclude with a discussion on how such limitations can be addressed in the context of automated function prediction methods, while we are rapidly approaching the $1000 genome era.

08.07.2013

Adam Petrusek - "Diversity and impact of invasive crayfish and the crayfish plague: old menace is back with new surprises"

Charles University, Prague, Czech Republic

Abstract: Crayfish plague, caused by an oomycete Aphanomyces astaci, is a well-studied invasive disease of wildlife with substantial conservationaland economic impact. Having stricken Europe already in the second half of 19th century, it has been substantially studied in the past, and became one of the best known diseases of aquatic invertebrates. Still, many aspects of its ecology and host-pathogen interactions are only being discovered in recent years. Original hosts of the crayfish plague pathogen are North American freshwater crayfish that are usually able to resist the infection without major symptoms or mortalities. Crayfish from other biogeographicregions are susceptible to the disease, which remains one of the key threats to native European populations. Several North American invasive crayfish species are found in European waters, three of these crayfish plague carriers being very widespread. In the talk, I will first summarise the history and present status of invasive crayfish in Europe, and their ecology and diversity. Afterwards, I will discuss the crayfish plague, its life cycle and impact, and some of the most interesting recent discoveries facilitated by development of molecular tools.

26.07.2013

Fani Papagiannouli - "Close contacts in the Drosophila testis: Crosstalk of germline and somatic cells promotes stem cell niche and testis homeostasis"

Centre for Organismal Studies (COS) Heidelberg, Germany

This seminar will take place on a special day and time: Friday at 14:00 at Biozentrum, Großhaderner Str. 2, 82152 Planegg-Martinsried. Also, it is in a different room than usual (B01.015)!

Abstract: Stem cells reside in microenvironments, known as the stem cells niches, that play an important role in stem cell behavior. The Drosophila testis provides a powerful system to study stem cell behavior. Stem cell niche and testis morphogenesis is achieved through the physical contact and diffusible signals exchanged between the germline and somatic cell populations. The cytoskeletal proteins Dlg, Lgl and Scrib are required in the somatic lineage for testis development and homeostasis with Dlg acting on survival, growth and membrane proliferation of the somatic cyst cells. On the other hand, the Hox gene Abd-B in the testis spermatocytes provides upstream positional cues to maintain niche architecture and localization, and ensure proper niche function and germline stem cell activity. Identification of Abd-B binding regions throughout the genome, revealed that Abd-B mediates its effects by directly controlling at multiple levels the localization, recycling and thus signaling activity of the Sevenless (Sev) ligand, Bride of Sevenless (Boss), via its direct targets src42A and sec63. Using genomic, genetic and molecular techniques combined with the related microscopy, I am interested in understanding the fundamental regulation of testis cell communication. In particular, my focus is to elucidate how testis-specific gene regulation and cytoskeletal components affect endocytosis, membrane trafficking as well as the signaling events that shape the germline-soma microenvironment and promote testis homeostasis.

Winter Semester 2012/13

29.10.2012

Katja Nowick - "Changes in transcription factor genes and gene regulatory networks during primate evolution"

TFome and Transcriptome Evolution, Bioinformatics, University of Leipzig, Germany

19.11.2012

Aurelien Tellier - "Ecological and evolutionary importance of soil seed banks for plant species"

Population Genetics Group, Center of Life and Food Sciences Weihenstephan, TU München, Germany

26.11.2012

Felicity Jones - "The genetics and genomics of stickleback adaptive diversity"

Molecular Mechanisms of Adaptation and Speciation, MPI for Developmental Biology, Tübingen, Germany

10.12.2012

Julien Dutheil - "Ancestral population genomics: sequencing the present to infer the past"

Evolutionary Bioinformatics, Institut des Sciences de l'Evolution de Montpellier, France

14.01.2013

Nicole Kammerer / Bernhard Busch - "Multiplatform-based sequencing: combining libraries, sequencing technologies and software tools"

DNA Sequencing and Bioinformatics, GATC Biotech, Konstanz, Germany

28.01.2013

Johannes Söding - "Protein structure prediction, transcriptional regulation, and core promoters"

Soeding Lab, Gene Center, Munich, Germany

04.02.2013

Harold P. de Vladar - "The different facets of evolutionary genetics: from bean-bag genetics to statistical mechanics & computer science"

Barton Group, Institute for Science and Technology Austria, Vienna, Austria