EES Seminar Series

Summer Semester 2025

28.07.25

Jon Bridle - Why do species have narrow niches? understanding limits to adaptation at ecological margins.

University College London, UK

Abstract: Understanding maximum rates of evolutionary change is crucial to understanding responses to rapid environmental change, and to the resilience of biological communities and their outputs in decades to come. Adaptation to novel environments may require genetic variation that is: (a) hidden from selection in native environments by adaptive plasticity and (b) may have a different genetic basis to that underlying existing local adaptation. I will discuss our work to understand the evolution and ecology of novel interactions with host plants and climate at the ecological margins of the UK Butterfly Aricia agestis, as well as the role of evolutionary responses in climate resilience across Lepidoptera more generally. I will also summarise our recent research to understand the genomics of plasticity to novel environments beyond the elevational margin of Senecio daisies in Sicily. Host: Richard Merrill

07.07.25

Violaine Llaurens - From ecological divergence to genetic architecture: what is driving sympatric speciation?

Collège de France, Paris

Abstract: Determining the evolutionary forces initiating and fuelling the speciation process is challenging, especially when population divergence occurs in sympatry. Sympatric speciation often involves complex interactions between ecological specialization generating divergent selection and the accumulation of genetic barriers to gene flow. Here we focus on a pair of sister-species of butterflies (M. achilles and M. helenor) observed in sympatry throughout the Amazonian basin, and sharing similar micro-habitat but diverging in the timing of male patrolling behaviour. Since M. helenor has a larger geographical range, we compared the temporal niche in sympatric and allopatric populations of this species and found a significant shift in patrolling hours, suggesting that the evolution of temporal niches might contribute to the speciation or reinforcement process. Using population genomics, we then reconstructed the history of speciation between these two species and investigated the heterogeneity in the level of genetic divergence throughout the genome. We found a very strong differentiation in the sexual chromosome (Z) as compared to the autosomes between species but not between populations within species. We then specifically tested for the effect of selection in such increased rate of evolution in the Z chromosomes and found significantly higher signals of positive selection in the Z vs. the autosomes in sympatric population, while such a signal was missing in the allopatric ones. Interestingly, we also noticed that the circadian gene Period, located on the Z chromosome, was found under positive selection throughout the genus Morpho. Altogether, our results raise questions on the implication of the Z chromosome in ecological specialization and speciation in sympatry. Host: Richard Merrill

30.06.25

Marie Lebherz - Exploring the Emergence of Newly-Evolved Expressed Open Reading Frames (neORFs) in Drosophila.

University Münster, Germany

Over the past decade, the study of de novo genes i.e. genes that originate from previously noncoding regions of the genome, rather than from the duplication or modification of existing coding sequences has gained increasing attention. To become a de novo gene, a noncoding sequence needs to aqcuire, at minimum, transcription as well as an open reading frame (ORF) with the potential for translation. Still, the precise mechanisms
underlying these processes are not fully understood.

In my talk, I will first discuss methodological approaches for detecting de novo genes and their precursors within genomes and transcriptomes. Next, I talk about the application of one of these approaches to a dataset of Drosophilagenomes and transcriptomes to investigate the early stages of de novo gene birth, specifically focusing on newly evolved expressed ORFs (neORFs). Our results show that neORFs are predominantly species-
specific, although a subset is shared across several species. Moreover, they differ from protein-coding genes in various features, including length, GC content, and expression level. Finally, I will address their noncoding homologs and highlight the mutations most often found there, which may help explain the emergence of these neORFs. Host: John Parsch

02.06.25

Thomas Schmitt- Ecology and evolution of cuticular hydrocarbons in solitary Hymenoptera

University Würzburg, Germany

Abstract: All insects investigated so far exhibit a complex blend of hydrocarbons (CHC) on their cuticle. These CHC profiles are often species and sex specific and play a crucial role in intra- and interspecific recognition processes and communication. Although CHC composition and function is studied intensively, our knowledge on the evolution of this ubiquitous trait is rather scarce. In order to understand the factors shaping these complex chemical profiles, we studied the function of hydrocarbons in solitary wasps’ nesting biology and antagonistic interactions of solitary predatory wasps and their brood parasites (Crabronidae, Vespidae, Chrysididae). These interactions involve chemical mimicry since CHCs of cuckoo wasps are suggested to be important cues for recognizing parasitisation processes. In my talk I will show how the use of hydrocarbons for prey preservation and the interaction between predatory wasps and their antagonists impacts the composition of complex CHC profiles and thus, potential recognition processes. Our research sheds light on the co-evolutionary processes selecting for ubiquitous chemical cues in Hymenoptera. Host: Sonja Grath

26.05.25

Armin Moczek - On the origins of novelty in development and evolution: insights through the study of horned beetles

Indiana University Bloomington, USA

Abstract: The origin of novel traits is among the most intriguing and enduring problems in evolutionary biology. It is intriguing because it lies at the heart of what motivates much of evolutionary biology: to understand the origins of exquisite adaptations, and the transitions and radiations that they fueled. It is enduring because it embodies a fundamental paradox. On the one hand, Darwin's theory of evolution is based on descent with modification, wherein everything new, ultimately, must come from something old. On the other hand, biologists are captivated by complex novel traits precisely because they often lack obvious homology to pre-existing traits. How, then, does novelty arise within the confines of ancestral developmental patterns and variation? Combining approaches from evolutionary developmental genetics, ecological genomics, behavioral ecology, and the biology of host symbiont interactions our research explores the genetic, developmental, behavioral, and ecological mechanisms, and the interactions among them, that promote innovation and diversification in the natural world. We enlist in this effort a diverse cast of non-traditional insect model systems, from treehoppers to fireflies, with horned beetles representing our focal taxonomic group. In this talk I will (i) explore the developmental genetic mechanisms underlying the origin and diversification of novel, exaggerated secondary sexual traits, (ii) investigate the evolution of sex-biased and nutrition- responsive development, and (iii) discuss the roles of symbioses and niche construction in organismal innovation, diversification, and adaptation. Host: Natascha Zhang

19.05.25

Tanja Schwander -The evolutionary causes and consequences of parthenogenesis: Insights from stick insects

University of Lausanne, Switzerland

Abstract: Parthenogenesis is predicted to have profound evolutionary consequences, as gamete production and the restoration of somatic ploidy levels via fertilization no longer take place, and male phenotypes are no longer exposed to selection. The empirical evidence for most predictions remains however scarce, partly because studies on isolated parthenogenetic species often conflate the effects of asexuality with species-specific patterns. To address this gap, we investigate independently evolved asexual species alongside their sexual relatives. In this talk, I will discuss the mechanisms driving the de novo evolution of parthenogenesis from sexual ancestors and present insights gained from comparative genomic and transcriptomic analyses of sexual and asexual stick insect species. Host: CAS and Axel Imhof

05.05.25

Karl Grieshop - The maintenance and identification of sexually antagonistic genetic variation

University of East Anglia, UK

Host: Bart Nieuwenhuis

Winter Semester 2024/25

03.02.25

Jana Isanta Navarro - Nutrients and the Food Web: Exploring Ecology and Evolution in Lake Ecosystems

University of Copenhagen - Denmark

Abstract: Humanity is altering the environment at an unprecedented pace and scale. Rising temperatures and CO2 levels, unsustainable phosphate mining—these are just a few of the many examples. Such rapidly changing conditions are creating or exacerbating stress on ecological communities and the species within them.
Stressors that affect survival and reproduction lead to shifts in selective pressures on organisms. Adaptive responses to these altered pressures can take various forms, including physiological phenotypic plasticity, changes in the microbiome, or evolutionary adaptation. These responses, in turn, can feedback into ecological processes at the population and community levels, ultimately influencing the functioning of entire ecosystems.
Understanding the intricate interplay between ecological and evolutionary processes that enable communities to navigate a changing world is crucial. This knowledge is essential if we are to predict, plan for, and manage the societal impacts of climate change effectively.
Join me in uncovering how ecosystem changes influence the ecology and evolution of aquatic organisms, and the pivotal role nutrients play in these processes. Host: Maria Stockenreiter

27.01.25

Sara Leonhardt - Food for health: the nutritional ecology of plant-pollinator interactions

Technische Universität München, Germany

Host: Alexander Keller

20.01.25

Joe Hoffmann - The effects of anthropogenic bottlenecks on genetic diversity and fitness in pinnipeds

Evolutionary Population Genetics, Bielefeld Universität, Germany

Abstract: In this presentation, I will describe research from my group investigating the effects of anthropogenic bottlenecks on genetic diversity and fitness in pinnipeds. The first part of the talk will take a comparative approach to explore how commercial hunting during the 18th and 19th centuries influenced genetic diversity and species viability. I will show that, although genetic diversity across species was strongly impacted by hunting, there is no clear relationship between genetic diversity and species viability. The second part of the talk will delve into the enigmatic case of the northern elephant seal, a pinniped that was hunted to the brink of extinction. I will present evidence suggesting that an extreme demographic reduction likely purged many of the deleterious alleles that would otherwise cause inbreeding depression. Host: Jochen Wolf

13.01.2025

Barbara Feldmeyer - Genome-wide selection signatures and environmental adaptation:
Insights from insects and trees

Senckenberg Biodiversity and Climate Research Centre Frankfurt/M, Germany

Abstract: Environmental adaptation is a fundamental process shaping the evolutionary trajectories of species. Organisms must continually evolve to cope with changing environmental conditions and exploit novel ecological niches. To understand the genetic basis of this adaptation, we employed genome-wide association studies (GWAS) and transcriptomic analyses on diverse organisms. Our research focused on climate adaptation, investigating how species adapt to varying temperature regimes and other climatic factors. Our findings reveal a complex genetic architecture underlying climate adaptation, involving polygenic traits. We identified a broad range of traits, from physiological to behavioral, that are influenced by climate. This suggests that adaptation to climate change can be rapid, but often involves a complex interplay of genetic factors. By integrating GWAS data with ecological niche modeling, we can improve predictions of species persistence under future climate scenarios. Understanding the genetic basis of adaptation can help us anticipate how species may respond to environmental challenges and inform conservation strategies. Host: Dirk Metzler

09.12.24

Susanne Foitzik -(Co)Evolution and Molecular Regulation of Behavioral, Chemical, and Life History Traits in Ants

Johannes Gutenberg Universität Mainz, Germany

Abstract: Social evolution in insects has driven the development and optimization of key traits such as division of labor, extended lifespan, and parasite defense. Our research focuses on Temnothorax ants, exploring molecular regulation underlying behavioral, chemical, and life history traits, with an emphasis on gene expression. We identified epigenetic mechanisms, including histone acetylation, and candidate genes that regulate division of labor and circadian rhythms. Functional annotation via RNAi revealed a role for vitellogenin-like A in modulating nursing behaviors and responsiveness to social cues. Differential expression of antennal odorant receptor genes suggests they act as sensory filters, influencing task-related cue responsiveness. Odorant perception and recognition cues further play a role in coevolutionary dynamics between social parasites and their hosts. Through resequencing and GWAS of over 120 colonies from 10 populations of slavemaking ants and their hosts, we identified SNPs associated with behavioral and chemical traits, parasite pressure, and climate variables, with host antennal transcriptomes correlating to parasite prevalence. Additionally, we investigated a parasitic cestode affecting ant physiology, finding that infected workers exhibit extended lifespans due to antioxidant proteins released into their hemolymph, impacting behavior and longevity through mechanisms still under study, including epigenetic modifications. Temnothorax ants, with their manageable societies, provide valuable insights into the molecular foundations of social regulation and defense, shedding light on their evolutionary trajectories. Host: Richard Merrill

02.12.24

Nick Barton - The Evolution of Reproductive Isolation in Snapdragons

IST Austria

Abstract: In the eastern Pyrenees, two populations of snapdragons (Antirrhinum majus) differ in flower colour, and meet in a narrow hybrid zone. In a long-term study, we have genotyped ~34,000 individuals at ~100 SNP markers, allowing us to build a pedigree that gives direct estimates of dispersal and fitness. This complements analysis of clines at six loci, which gives independent estimates of selection. Despite the striking divergence in flower colour, gene flow is only restricted across a small fraction of genome. Even with such a detailed study, it is difficult to disentangle the functional basis of selection, and still harder to find out the original causes of divergence. Host: Richard Merrill/CAS

25.11.24

Laurent Frantz - Tracking animal domestication using palaeogenomics

Faculty of Veterinary Medicine, LMU

Abstract: Our group’s research focuses on understanding how human activities have altered the evolutionary trajectory of wild and domestic species. We use a multidisciplinary approach, encompassing genomics, evolutionary biology, archaeology, anthropology and conservation biology. We exploit the power of (palaeo-)genomics (e.g. ancient DNA) to contrast current patterns of genetic diversity to those in the past: this allows us to track evolutionary processes including (artificial) selection, extinction, speciation and domestication through time. In this seminar, I will present some of our unpublished work focusing on the domestication of dogs and pigs, their global dispersal, and the transformative effects that their interactions with humans over millennia has had on their genome. Host: Richard Merrill/Jochen Wolf

18.11.24

Edward Ricemeyer - Genomes of an ancient hybrid fish defy the predicted costs of asexual reproduction.

University of Missouri

Abstract: Sexual reproduction is ancient and ubiquitous despite its obvious disadvantages of needing to find a suitable mate and the skewed investments of the sexes in the production of offspring. Therefore, the meiotic recombination and reallocation of alleles associated with sexual reproduction have long been considered to be necessary to maintain a viable genome in the face of mutational pressure and changing environments. According to this theory, a lineage without sex will rapidly accumulate deleterious mutations and eventually go extinct. Despite this dire prognosis, asexual organisms, although rare, are more widespread than previously thought, and many have existed for longer than theory predicts is possible. One such species is the Amazon molly Poecilia formosa, a clonally reproducing fish arising from a single hybridization of P. latipinna and P. mexicana over 100 thousand years ago. We test these predictions of the costs of asexual reproduction in the genomes of these three species, finding evidence for only a small increase in mutational load in the asexual P. formosa compared to its sexual progenitors. Instead, mutation rates across the three genomes are more reflective of ancestry than of reproductive mode. The prevalence of gene conversion between the haplotypes of P. formosa, which is significantly higher in coding sequence, suggests a mechanism through which deleterious mutations can be purged and beneficial mutations can be fixed in the absence of meiotic recombination. Together, these findings present some of the first contradictory evidence against a set of long-standing hypotheses about the negative consequences of asexual reproduction. Host: Richard Merrill