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
Speakers are invited from mainly around Europe across all three areas (Evolution, Ecology and Systematics), leading to a wide-range of presented research topics.
Winter Semester 2019/20
Alistair McGregor - Investigating the Evolution of Developmental Regulation in Spiders and Flies
Oxford Brookes University, UK
Abstract: Research in my lab focuses on questions that are key to understanding animal evolution: How does the genetic regulation of development evolve and what is the genetic and developmental bases for morphological variation within and between species. To address these questions we study the genomics and genetics of the development of the spider Parasteatoda tepidariorum, and gene regulation and morphological evolution among flies of the Drosophila melanogaster species subgroup. In this talk I will present our recent work on the regulation of segmentation in Parasteatoda, and on investigating cis-regulatory logic and morphology evolution among Drosophila species. Research in my lab focuses on questions that are key to understanding animal evolution: How does the genetic regulation of development evolve and what is the genetic and developmental bases for morphological variation within and between species. To address these questions we study the genomics and genetics of the development of the spider Parasteatoda tepidariorum, and gene regulation and morphological evolution among flies of the Drosophila melanogaster species subgroup. In this talk I will present our recent work on the regulation of segmentation in Parasteatoda, and on investigating cis-regulatory logic and morphology evolution among Drosophila species.
Marie Herbestein - Unlocking the paradox of imperfect mimicry using ant mimicking spiders
Macquarie University, Australia
Abstract: Batesian mimics are deliciously palatable species that gain protection from a predator by resembling a defended or unpalatable model. Theory predicts that mimics that closely resemble their model should have the greatest advantage, while inaccurate mimics should be recognised and attacked by predators. This is all fine and good, but in reality, we find that mimics are highly variable, some are excellent in mimicking their model and others are rubbish at it. There are many different hypotheses that try to explain the persistence of inaccurate mimics, and we have a research project at Macquarie University that tests these ideas using ant mimicking spiders. In this seminar, I will illustrate the range of mimic fidelity in ant mimicking spiders and present the evaluation of some of the common hypotheses. If time and technology permits we will even play an online game.
Julien Gagneur - Modelling the regulatory code: From basic biology to clinical research
Technical University of Munich, Germany
My lab is interested in understanding how gene expression is encoded in genomes, and how to leverage this knowledge for medical application. To this end, we employ statistical modeling of ‘omics data and work in close collaboration with experimentalists. I will provide an overview of recent studies on RNA metabolism and protein expression control and on deep learning based models of cis-regulatory elements. I will also report on methodologies for using RNA-sequencing as a powerful companion tool to genome sequencing for pinpointing causes of rare genetic disorders.
Aurelien Tellier -Inference of past demography and life history traits from whole genome genetic and epigenetic data
Technical University of Munich, Germany
Several methods based on the Sequential Markovian coalescence (SMC) have been developed to use full genome sequence data to uncover population demographic history, which is of interest in its own right and is a key requirement to generate a null model for selection tests. While these methods can be applied in principle to all possible species, they have two main limitations: 1) the underlying assumptions are sexual reproduction at each generation and no overlap of generations, and 2) the inference accuracy depends on the ratio of recombination to mutation. However, in many plants, invertebrates, fungi and other taxa, these assumptions are often violated due to different ecological and life history traits, such as self-fertilization, long term dormant structures (seed or egg-banking) or large variance in offspring production. In this presentation I will first describe a novel SMC-based method which we developed to infer 1) the rates of seed/egg-bank and of self-fertilization, and 2) the populations' past demographic history. Using simulated data sets, we demonstrate the accuracy of our method for a wide range of demographic scenarios and for sequence lengths from one to 30 Mb using four sampled genomes. As a test, we apply our method to a Swedish and a German population of Arabidopsis thaliana demonstrating a selfing rate of ca. 0:87 and the absence of any detectable seed-bank. In contrast, we show that the water flea Daphnia pulex exhibits a long lived egg-bank of three to 18 generations. Second, I will provide recommendations for the use of SMC-based methods for non-model organisms, highlighting the importance of the per site and the effective ratios of recombination over mutation. Third, I will show some preliminary results on the effect and estimation of a violation of the Wright-Fisher model assumption, namely the large variance in offspring production which is common to fish, invertebrates and fungal species. Finally, if time permits, I will show some preliminary results on the use of methylation patterns to enhance the power of inference under an SMC model using both genetic and epigenetic markers.
Björn Benning - Bryozoa in a nutshell: evolution, ecology, systematics
Oberösterreichisches Landmuseum Linz, Austria
Bryozoa are an exclusively colonial and clonal phylum with some 6000 described species that predominantly inhabit marine environments from the intertidal to abyssal depths. The most diverse clade in modern seas, the Cheilostomatida, are particularly interesting study objects as they show a number of evolutionary innovations and trends since their origin in the Late Jurassic. Their ability during colony growth to produce clones that differ slightly in form and function have resulted in the development of a variety of specialised zooids, in the division of labour at zooid and colony level, and therefore in the evolution of highly integrated colonies. As some of these colonies show the behaviour of a free-living solitary animal, they may be regarded as „superorganisms“.
I will give a quick overview of the Bryozoa as a whole, and then detail how the cheilostomatids became so successful in the present-day oceans.
Peter Kraiczy - A view to a kill: role of complement on host speciation of Lyme disease spirochetes
Goethe University Frankfurt, Germany
In nature, Lyme disease (LD) spirochetes like other blood-borne pathogens circulate in a stipulated vector-host-vector transmission cycle without affecting their tick vectors or their natural reservoir hosts. One of the most important findings in recent years is that the different genospecies of the so-called Borrelia burgdorferi sensu lato complex are maintained in nature by different spectra of vertebrate host species suggesting that host-specificity is independent of extrinsic ecological factors. Also, reservoir competence appears to be variable and depends on the combination of the Borrelia genospecies and vertebrate host species. In addition, natural reservoir hosts do not appear to develop a disease and do not have typical symptoms of borreliosis. It is now accepted that the innate immune system, in particular complement is a major determinant of host-specificity (i.e. niche-adaptation) of LD spirochetes. One of the strategies that LD spirochetes successfully utilize to escape from the innate immune defense mechanisms is to produce outer surface proteins that are capable of preventing complement activation on the spirochete surface by binding to complement regulator Factor H. These complement-regulator acquiring surface proteins (CRASPs) encompass CspA, CspZ, and OspE paralogs. The genes encoding these CRASPs differ in their expression patterns during the tick-to-host infection cycle, implying that these proteins may exhibit different roles during infection. While the means by which spirochetes overcome the immune defences of their natural reservoir hosts are far from being completely understood, there is a growing body of evidence suggesting that the species-specific binding pattern of Factor H plays a pivotal role for immune evasion of LD spirochetes during transmission cycles of various vertebrate hosts and, therefore, in the global ecology of LD.
CNRS Paris, France
Seminar cancelled. Will take place in summer semester.
Summer Semester 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
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.
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.
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.
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.
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.
Cristina Tuni - A journey inside the nuptial gift of a spider
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.