Seminar Series
Every semester, EES organise a seminar series, which takes place on Mondays at 16:00 at Biozentrum, Großhaderner Str. 2, 82152 Planegg-Martinsried, Lecture Hall B 01.027
External speakers are invited across all three areas (Evolution, Ecology and Systematics), leading to a wide-range of presented research topics.
Summer Semester 2024
09.09.2024
Max Farnworth - Distinct selection regimes shaping the evolution of integrative
centres in the brains of Heliconiini butterflies
University of Bristol
Abstract: Central neural circuits integrate sensory and internal information to cause a behavioural output.
Evolution modifies such circuits to generate adaptive change in sensory detection and behaviour, but it
remains unclear how selection does so in the context of existing constraints. We have explored this
question by analysing evolutionary dynamics in the circuits of the insect mushroom body and central
complex. While the central complex seems to be largely conserved in term of size and shape, there is
huge diversity in the mushroom body circuit. However, an empirical framework as well as a general
understanding of how evolution modifies the function and architecture of these circuits is largely
lacking. To address this, we leveraged the recent radiation of a Neotropical tribe of butterflies, the
Heliconiini (Nymphalidae), which show a massive amount of variation in mushroom body size over
comparatively short phylogenetic timescales, linked to specific changes in foraging ecology, life history
and cognition. We combined immunostainings of structural markers and neurotransmitters as well as
neural injections with comparative, quantitative datasets to understand the mechanism by which such
an extensive increase in mushroom body size is accommodated through changes in its internal as well
as its external circuitry. Inside the mushroom bodies, we identified that only some Kenyon cell
populations expanded with a higher rate than others, in those Heliconiini faced with specific cognitive
demands for their foraging ecology. We also identified that feedback neurons external to the
mushroom body show a large increase in cell number. This is accommodated with large conservation
inside central complex and peripheral circuitries, with highly intriguing specific differences. Our results
demonstrate an interplay of evolutionary malleability inside the mushroom body lobes and functional
constraints inside connected circuits as an evolutionary pathway guiding adaptation in cognitive ability
through distinct selection regimes.
13.05.2024
Linda Weiss -Molecular Mechanisms of phenotypic plasticity: Environment perception, signal transmission and the development of adaptive phenotypes in the freshwater crustacean Daphnia
Ruhr University Bochum
Abstract: Phenotypic plasticity describes the ability of an organism to respond to changing environmental conditions by the adaptation of its phenotype. Thereby, organisms can conquer environments with fluctuating conditions as their genotype is geared with adaptive strategies increasing the individual’s fitness. The freshwater crustacean Daphnia reacts highly plastic to a wide variety of environmental cues, by developing adaptive context-dependent phenotypes. I will present the progress that has been made in deciphering mechanistic underpinnings underlying adaptive strategies in Daphnia. I focus on inducible defence expression as well as environmentally induced diapause. These strategies allow Daphnia to overcome harsh environmental conditions. In this context, causes of climate change negatively affect these adaptive strategies, makig Daphnia susceptible to anthropogenic environmental challenges.
(host: Mia Stockenreiter)
27.05.2024
Vicencio Oostra - How butterflies cope with the seasons - mechanisms, evolution and ecology of seasonal phenotypic plasticity
Queen Mary University of London, UK
Abstract: Phenotypic plasticity – the conditional expression of different phenotypes from the same genome in different environments– is a key adaptation to environmental variability. It is particularly important in seasonal habitats, where ecological pressures differ dramatically through the year. Understanding how organisms have adapted in the past to changes in seasonality can help us predict how they may adapt to future changes.The work in our lab addresses open questions in phenotypic plasticity using tropical butterflies as models. How do developing larvae or adult butterflies sense the environment and upcoming seasonal changes? How is gene expression regulated by the environment, and how does this lead to alternative morphology, physiology or behaviour? What genetic variation for these environment-sensing pathways segregates in natural populations, and what role does that variation play in local adaptation? Is the same variation involved in evolution of plasticity over longer evolutionary timescales? How does the ability to express alternative phenotypes vary across ecological gradients?Here I will present previous and ongoing work in our lab aimed at resolving these questions using tropical butterflies. We apply experimental approaches, natural populations, transcriptomics and genomics to Satyrinae from the Old World tropics and Neotropical Biblidinae. We study how they express different reproductive physiology and wing pattern between dry and wet seasons, and how this plasticity evolves between seasonal and aseasonal environments.
host: Richard Merrill (merrill@bio.lmu.de)
03.06.2024
Simon Segar- Caterpillars, chemicals, mountains and more (including the importance of local lore).
Harper Adams University, UK
Abstract: Plants, the insects that feed on them and their insect predators to comprise 75% of terrestrial macro diversity. These networks underpin many of the ecosystem services that we rely on for survival and understanding how they are structured is a priority. Here I attempt to synthesise ten years of research in tropical and temperate biomes focussed on the questions: Why do insects eat what they eat? And why are there so many of them? This is very much a team effort and I draw extensively on historical data from a tropical mountain and the surrounding lowland forests to answer these questions. Throughout the presentation I will highlight the role of individuals and local communities, especially where an intimate understanding of these fascinating habitats was required. We start our journey by attempting to predict structure in complex food webs using chemical traits and phylogeny. Can we draw any generalities at this broad scale and pull-out key nodes in our food web? Zooming in on dominant plant hosts helps to refine our predictions and incorporate increased chemical diversity through targeting key groups of compounds. Armed with a set of focal compounds and some expectations on how these organisms ‘should’ interact we assess chemical turnover across ecological gradients, and test how well this explains insect herbivore community structure. We work within a developing framework for understanding chemical diversity. Our results highlight how broad ecological data sets can inform more targeted mechanistic approaches, and our journey (to date) ends with a set of feeding experiments on individual caterpillars where we explore the fate of individual compounds from leaf to larva to adult. Many questions remain, but I hope that our synthesis is of use to those exploring the chemical diversity of insects on plants.
host: Richard Merrill (merrill@bio.lmu.de)
10.06.2024
Nicola Nadeau - Polygenic adaptation in Heliconius butterflies
Sheffield University, UK
Abstract: Arguably the majority of traits are controlled by large numbers of genes, yet our understanding of the genetic basis of phenotypic variation is biased towards traits that are controlled by a small number of major effect loci, largely because these are the easiest to study. In this talk I will present work investigating divergence in quantitative traits in two species of Heliconius butterflies, H. erato and H. melpomene, which have undergone parallel radiations across South America. Firstly, we investigate clines in iridescent structural colour. Unlike previously-studied colour-pattern clines in these species, iridescence shows continuous variation, due to continuous variation in scale nanostructures, with very broad geographic clines. Using crosses between populations, gene expression analyses and developmental imaging, we identify candidate genes that control of some of this variation. Secondly, we have been working on altitudinal clines, where the butterfly populations show little obvious phenotypic difference, but we find evidence for morphological, physiological, genetic and gene expression variation, associated with altitude.
host: Richard Merrill (merrill@bio.lmu.de)
17.06.2024
Carina Mugal - An integrative omics approach to study speciation in Ficedula flycatchers
Laboratory of Biometry and Evolutionary Biology, Lyon
Abstract: The recent rise of high-throughput sequencing technologies has significantly improved our ability to study the molecular mechanisms that underlie reproductive isolation and speciation in natural species. Population-level whole-genome sequencing can be employed to characterize the genomic differentiation landscape of diverging species and to identify relevant genetic loci and/or evolutionary processes. Other omics technologies, such as transcriptomics and epigenomics, provide a complementary angle to study the divergence of molecular phenotypes and their relevance to reproductive isolation and speciation. Here, we take advantage of these technologies and combine multiple omics approaches for an ecological model system of speciation research, the collared flycatcher and the pied flycatcher. While classical speciation genomics approaches reveal a role of genomic architecture in shaping the differentiation landscape, they fail to reveal the evolutionary history of speciation in our study system. The integrative approach, however, enables us to identify molecular processes of interest. Our analyses provide evidence that differential transcription patterns between the collared flycatcher and the pied flycatcher are associated with genomic differentiation and differential methylation of the promoter region, particularly for genes with CGI promoters. However, these mutational processes fail to explain transcriptional dysregulation observed in several organs of the F1 hybrids. In addition, contrary to observations in other species, transcriptional dysregulation appears not to be the basis of hybrid sterility. Instead, initial evidence suggests a role of meiotic recombination regulation in hybrid sterility and reproductive isolation.
host: Jochen Wolf (j.wolf@bio.lmu.de)
24.06.2024
Dang Liu - Population Genomics of Austronesian Peoples Sheds Light on the Human Settlement of the Pacific
Institute Pasteur, France
Abstract: The Austronesian language family is one of the largest in the world and the most widespread across the Pacific. Its geographical distribution is thought to reflect the “Austronesian expansion”, which posits that a small group of farmers from Taiwan expanded, from 5,000 years onwards, to numerous islands across the Indian and Pacific Oceans, reaching as far as Madagascar to the west and Easter Island to the east. Reconstructing the detailed history of this large-scale expansion helps understanding how humans have settled pristine insular ecosystems and has attracted research across many disciplines. Over the decades, simple syntheses of the migration routes have been proposed, as well as subsequent admixture with different groups, including the indigenous Papuan-speaking people and recent European settlers. Yet, many questions remain unanswered, such as the tempo and timing of the migrations, and new questions have emerged from recent genomic studies. In this seminar, I will focus on how genomics studies of Austronesian populations can illuminate the human settlement of the Pacific islands and the demographic and cultural processes that have been at play. Specifically, I will present my past and current work relating to Austronesian populations from Taiwan, New Guinea, to Polynesia, showing how historical migrations have shaped their genetic structure, linguistic differences, and ultimately, their phenotypic diversity. Taken together, my genetic studies support the notion that the human settlement of the Pacific involved multiple, long-distance waves and interactions, contributing to the establishment of the unique cultural and biological diversity of the region.
host: Jochen Wolf (j.wolf@bio.lmu.de)
08.07.2024
Luisa Pallares - Exploring the environment-dependent nature of genotype-phenotype maps in Drosophila.
MPI Tübingen, Germany
Abstract: Genotype-phenotype maps are a core concept in evolutionary biology, however building comprehensive maps for complex traits is challenging given the large samples sizes and precise environmental control that is needed to find small effect associations between genetic and phenotypic variation. We are using outbred Drosophila melanogaster populations to bypass such limitations and dissect the genetic basis of complex traits. I will discuss first, the degree to which genotype-by-environment interactions are core to understanding G-P maps, and second, our ongoing efforts to understand the environmental and genetic basis of phenotypic robustness, going from gene expression to morphological to functional robustness.
host: John Parsch (parsch@bio.lmu.de)
Winter Semester 2023/24
30.10.2023
Jonna Kulmuni -Semipermeable species boundaries and adaptive potential of hybridization
University of Amsterdam
Abstract: Hybridization is widespread across the Tree of Life, and it is predicted to increase due to climate change and human action, which bring previously isolated populations into contact. Increased rate of hybridization can lead to erosion of species barriers and biological diversity, but it can also provide the raw material for adaptation via introgression or increased genetic diversity. Using mound-building wood ants I show both deleterious and beneficial consequences of hybridization. Moreover, evolution of hybrid populations is repeatable at the genomic level, suggesting some outcomes of hybridization could be predictable. With on-going climate change semipermeable species boundaries may provide an advantage and allow persistence of populations in the new environmental conditions.
Host: Richard Merrill (merrill@bio.lmu.de)
06.11.2023
Claudia Bank - Epistasis and adaptation on fitness landscapes
University of Bern
Abstract: Epistasis occurs when the effect of a mutation depends on its carrier's genetic background. Although increasing evidence indicates ubiquitous epistasis for fitness, its role during evolution is debated. Fitness landscapes are mappings of genotype or phenotype to fitness, which capture the full extent and complexity of epistasis. Theoretical studies of fitness landscapes have shown how epistasis affects the path and the outcome of evolution. In addition, empirical fitness landscapes, in which the competitive fitness of sets of tens to thousands of connected genotypes was measured, have shown that epistasis is common and depends on the measure of fitness, the choice of mutations for the fitness landscape, and the environment in which fitness was assessed. Here, I present an overview of the field of evolutionary fitness landscape research and highlight ongoing work in my research group that aims at bridging the gap between fitness landscape theory and the role of epistasis in nature.
Host: Dirk Metzler (metzler@bio.lmu.de)
13.11.2023
Jordan Martin - Social drive explains rapid adaptation and eco-evolutionary feedback in small-scale human societies
University of Zurich
Abstract: Social interactions play a crucial role in generating feedback between ecological and evolutionary dynamics, due to their joint effects on the expression and selection of functional traits. Developing generalizable models of eco-evolutionary feedback in social environments is, therefore, crucial for understanding convergent social evolution across the natural world, as well as for predicting population growth or decline in response to ongoing environmental change. In this talk, I will present a novel eco-evolutionary feedback model developed during my PhD research, which attempts to explain otherwise paradoxical patterns of rapid adaptation in small-scale human societies. This ‘social drive’ model demonstrates how phenotypic plasticity among group members can generate and maintain feedback between the quantitative genetic causes and ecological effects of social interactions in fluctuating environments. Using extensive long-term data on the indigenous Tsimane people of Bolivia, I then provide strong empirical support for the predictions of this social drive model. Results show how (i) indirect genetic effects due to plasticity among Tsimane neighbors are accelerating the contemporary adaptation of fertility, and also how (ii) density- and frequency-dependent selection among Tsimane neighbors is acting to maintain these accelerating effects across generations.
Host: Niels Dingemanse (n.dingemanse@bio.lmu.de)
20.11.2023
Stefan Prost - The use of genomics for applied conservation.
University of Oulu
Abstract: Global change is impacting wildlife around the world, making conservation of threatened species and environments paramount. State-of-the-art genomic methods can be used to better understand threatened species and to inform conservation management strategies (both in situ and ex situ). However, efficient conservation can only be achieved when science, policy and society work together. In this talk, I will highlight different modern genomic techniques and how they are being used for applied conservation and to inform policy. I will also show how some methods can be used for local capacity building, education and citizen-science to support conservation of threatened species and environments around the world.
Host: Sarah Mueller (s.mueller@bio.lmu.de)
27.11.2023
Melanie Dammhahn - Patterns and consequences of individual variation in landscapes of fear: who takes the risk and does it matter?
University of Münster
Abstract: To eat or to feed others - that is one of the most fundamental problems governing animal behaviour. Besides direct predation risk, the mere presence of predators might change prey foraging behaviour. This perceived predation risk varies in space and time creating a landscape of fear. Hitherto, landscapes of fear have been studied as species-specific layers, assuming that each individual of a species perceives the same risk. However, individuals differ in risk-taking behaviour. In this talk, I will present results of empirical studies in which we illuminated patterns and consequences of individualised landscapes of fear.
Host: Niels Dingemanse (n.dingemanse@bio.lmu.de)
4.12.2023
Linda Weiss - Molecular Mechanisms of phenotypic plasticity: Environment perception, signal transmission and the development of adaptive phenotypes in the freshwater crustacean Daphnia
Ruhr University Bochum
Abstract: Phenotypic plasticity describes the ability of an organism to respond to changing environmental conditions by the adaptation of its phenotype. Thereby, organisms can conquer environments with fluctuating conditions as their genotype is geared with adaptive strategies increasing the individual’s fitness. The freshwater crustacean Daphnia reacts highly plastic to a wide variety of environmental cues, by developing adaptive context-dependent phenotypes.
I will present the progress that has been made in deciphering mechanistic underpinnings underlying adaptive strategies in Daphnia. I focus on inducible defence expression as well as environmentally induced diapause. These strategies allow Daphnia to overcome harsh environmental conditions. In this context, causes of climate change negatively affect these adaptive strategies, makig Daphnia susceptible to anthropogenic environmental challenges.
Host: Maria Stockenreiter (stockenreiter@bio.lmu.de)
29.01.2024
Nico Posnian - Georg-August-University Göttingen (postponed to the next semester)
Host: Richard Merrill (merrill@bio.lmu.de)
05.02.2024
Nathan Baker - The spatio-temporal patterns of European riverine biodiversity
Nature Research Centre, Lithuania
Abstract: Like a fingerprint, no two riverine communities are alike. Then again, since riverine communities are in a constant state of flux shifting and changing both spatially and temporally, a community’s uniqueness is only but a snapshot representing an exact moment in time, the moment in which it was sampled. By collecting enough of these ‘snapshots’ we can derive broader ecological patterns and, with coupled snapshots of environmental conditions, explore their potential drivers. Accordingly, my research addresses two simple questions: HOW and WHY freshwater biodiversity is changing. Using an ecological and statistical approach, I explore the spatio-temporal patterns of a changing freshwater landscape, first at a very localized scale, then at a supraregional scale, and lastly at the pan-European scale. Findings show that freshwater biodiversity is context dependent, with local and regional factors playing key roles in shaping the observed patterns. In a nutshell, European freshwater biodiversity is changing, with some parts showing improvements, while others showing deterioration. This makes monitoring and mitigation efforts challenging, since the “blanket” approach is not as effective as once thought. So, where to from here? The short answer: it’s complicated. The long answer: After some initial recovery, European freshwater biodiversity is entering a new era of challenges. It is up to us to mitigate these challenges, beginning with better predictive tools, conscious planning, and improved monitoring.
Host: Sarah Mueller (s.mueller@bio.lmu.de)
Summer Semester 2023
08.05.2023
Hannah Rowland - How toxins mediate ecological interactions - C A N C E L L E D
MPI for Chemical Ecology, Jena, Germany
Abstract: My research examines how toxins mediate ecological interactions between plants, herbivores, and predators. My primary study system is centred around toxic steroidal heart poisons produced by milkweed plants. I also have major projects on poison frogs, tiger moths, and snakes. My goal is to understand how multi-trophic interactions lead to evolutionary innovation and diversification. To achieve this I integrate research across different biological levels of organisation, and use multidisciplinary tools from small molecule chemistry, to molecular and cell biology, to whole animal behaviour. I will present my research examining the evolution of – and new adaptations to – toxicity, that has broad implications for the evolutionary dynamics of signalling systems and animal behaviour. My talk will addresses specific evolutionary questions such as the role of epistasis and contingency in molecular evolution, and how novel protein functions arise.
Host: Richard Merrill (merrill@bio.lmu.de)
15.05.2023
Stuart Baird- Genome Polarisation
IVB, Czech Academy of Sciences, Czech Republic
Abstract: Incomplete barriers to geneflow allow admixed inheritance across, not down the tree of life. This may change the rate of adaptation in times of rapid environmental shifts such as the current climate crisis.To understand this potential requires knowledge of the prevalence of barriers in nature and their barrier strength. Genome polarisation paints genomes with respect to the sides of barriers, and so may help in building this knowledge base.
Host: Jochen Wolf (j.wolf@bio.lmu.de)
22.05.2023
Sean Stankowski - Selection on many loci drove the origin and spread of a key innovation
IST, Austria
Abstract: Key innovations are fundamental to biological diversification, but their genetic architecture is poorly understood. A recent transition from egg-laying to live-bearing in Littorina snails provides the opportunity to study the architecture of a young innovation. Samples do not cluster by reproductive mode in a genome-wide phylogeny, but local genealogical analysis revealed numerous genomic regions where all live-bearers carry the same core haplotype. Associated regions show evidence for live-bearer-specific positive selection, and are enriched for genes that are differentially expressed between egg-laying and live-bearing reproductive systems. Ages of selective sweeps suggest live-bearing alleles accumulated gradually, involving selection at different times in the past. Our results suggest that innovation can have a polygenic basis, and that novel functions can evolve gradually, rather than in a single step.
Host: Jochen Wolf (j.wolf@bio.lmu.de)
05.06.2023
Ivan Kolidarov - Evolution of Functionally Novel Genes: Insights From the Animal Venoms
(TUM, Germany)
Abstract: In this talk, we will explore the evolution of novel functions in animals, with a focus on toxins in venomous bees and snakes. We will base our discussion on a combination of genomic and proteomic data, as well as tools such as synteny, phylogenetic and protein space AI analyses that were used to investigate the origin and diversification of toxin-encoding genes. We will delve into the mechanisms of gene duplication and its relationship to the emergence of novel biological functions, illustrating it by the evolution of g2 family of phospholipase A2 in Vertebrata and the 3-finger toxins in caenophidian snakes. Our reconstruction of evolutionary history suggests that duplication events and the resulting functional redundancy have played a significant role in the evolution of these gene families. However, our research also highlights that the evolution of functionally diverse genes is a complex process that is shaped by a variety of historical, genomic, and ecological factors, and that neofunctionalization may not always be the best model to explain the evolution of genetic novelty
Host: Andrea Pozzi (pozzi@bio.lmu.de)
19.06.2023
Daven Presgraves - The roles of selfish genes during complex speciation in Drosophila
University of Rochester, USA and Wissenschaftskolleg zu Berlin, Germany
Abstract: Eukaryotic genomes contain a diversity of evolutionarily “selfish” genetic elements (SGEs) that obtain transmission advantages at the expense of their host carriers. SGEs tend to use one of two broad strategies: over-replicate relative to the host genome (e.g., transposable elements) or distort Mendelian transmission (e.g., meiotic drive elements). Sex chromosomes, it turns out, are especially susceptible to the accumulation of meiotic drive elements that, by distorting X versus Y chromosome transmission, bias progeny sex ratios. Such “sex-ratio drive” potentiates evolutionary conflicts of interest between drivers and drive-suppressors at X-linked, Y-linked, and autosomal loci. Molecular arms races arising from recurrent bouts of sex-ratio drive and suppression can have far reaching consequences for genome evolution and for speciation. In this talk, I will show how a system of sex-ratio drivers & suppressors evolved recently and then rapidly amplified and diversified among three closely related species of Drosophila— D. simulans, D. mauritiana, and D. sechellia. I will discuss how this drive system contributed to the evolution of genetic incompatibility and to the history of gene flow among between species.
Host: John Parsch (parsch@bio.lmu.de)
26.06.2023
Rahel Sollman- Hierarchical statistical models in wildlife ecology
Leibniz Institute for Zoo and Wildlife Research
Abstract: Hierarchical statistical models (HSM) are multi-level models in which one level is conditional on another. These models are used in a myriad ways, for example, to account for nested sampling designs, to model processes on multiple scales (e.g., spatial or temporal), or to disentangle ecological from observation processes. The latter is particularly important in wildlife research, as animals are notoriously difficult to observe. As a result, ecological state variables of interest, such as species presence or abundance, are observed imperfectly, e.g., a species may be present but never detected by sampling; or a population may consist of more individuals than are counted. In my talk, I will provide an overview over HSM that address this form of observation bias, also called imperfect detection, by describing an observation model that is conditioned on the true, but latent, underlying ecological state. I will present occupancy models, in which repeated species-level detection/non-detection data collected across multiple sites (observation) are used to estimate species occurrence (ecological state) while accounting for imperfect species detection, and which are often fit to joint data from multiple species (i.e., community occupancy models). I will touch on count-based models to estimate abundance, with a focus on distance sampling, in which individual detection probability is described as a declining function of distance from the observer, allowing for estimation of abundance (ecological state) from counts (observations). Finally, I will discuss traditional and spatial capture-recapture, the gold standard of abundance estimation, based on repeated detection data of animals that can be identified individually, through natural or artificial marks. I illustrate all approaches with case studies that also showcase extensions to the basic models. Overall, HSM is a flexible framework that can be tailored to specific sampling circumstances to investigate spatio-temporal processes in wildlife ecology while addressing imperfect detection.
Host: Richard Merrill (merrill@bio.lmu.de)
03.07.2023
Andreas Fleischmann - Food, sex and crime: interactions between carnivorous plants and insects
Botanische Staatssammlung München
Abstract: Carnivorous plants are generally considered deadly traps for insects and small animals. However all of the currently known ca. 860 species of carnivorous plants have flowers that are pollinated by insects. How do they avoid eating their pollinators? Modes of prey attraction and pollinator "protection" are presented. Moreover, several insects have adapted to live in or on the traps of carnivorous plants, as herbivores (feeding on the carnivorous plants), kleptoparasites (feeding on the prey of carnivorous plants) or mutualists (in a symbiotic relationship with carnivorous plants). These specialized insect associates will also be illustrated in the talk, including their adaptions to survive in the deadly habitat they live in.
Host: Gundrun Kadereit (G.Kadereit@biologie.uni-muenchen.de)
10.07.2023
Markus Möst - The multifarious outcomes of hybridization and the consequences of life cycle variation
University of Innsbruck
Abstract: Hybridization and introgression are now recognized as important evolutionary processes that can facilitate speciation and rapid adaptation to new environments. However, a hybridization event may have various outcomes and may range from a collapse of species into a hybrid swarm, over hybrid speciation and adaptive introgression to a complete removal of hybrids and purging of introgressed alleles via intrinsic or extrinsic forces that may eradicate the traces of a hybridization event and contribute to the maintenance of stable specie boundaries. The results of a secondary contact may even differ within the same pair of species, for example along an extended contact zone or among multiple contact zones. Factors affecting the outcome and dynamics of hybridization include spatial heterogeneity and – often underappreciated – features of species’ life cycles, such as cyclical parthenogenesis or propagule banks. I will contrast different outcomes of hybridization and the role of life cycle in the Heliconius butterflies and a hybridizing Daphnia water flea species complex. I will highlight a few intriguing cases of adaptive introgression in Heliconius butterflies and continue with recent work leveraging whole-genome time series obtained from Daphnia resting eggs deposited in lake sediments reconstructing recent cases of secondary contact and interspecific hybridization following anthropogenic habitat disturbance through cultural eutrophication in European peri-Alpine lakes. Despite periods of extensive hybridization and extended backcrossing during ecological transitions, the parental species still exist as distinct units alongside hybrid lineages. I will discuss possible mechanisms reducing the impact of hybridization and highlight the role and interaction of life cycle features and spatio-temporal ecological heterogeneity in maintaining species boundaries in this hybridizing species complex. To conclude, I will discuss ongoing work studying the consequences of hybridization in a keystone species for its community and ecosystem.
Host: Richard Merrill (merrill@bio.lmu.de)