EES seminars 0910
From EESwiki
EES and Forschergruppe Seminars take place on Mondays at 17:00h in the Biozentrum, first floor, right lecture hall.
26/10/09. Dr Anthony Herrel. Why are mainland anoles different?
MNHN Paris, France
Website: http://webh01.ua.ac.be/funmorph/anthony/
Abstract: Anolis lizards have become a model system for the study of adaptive radiations as species with similar morphologies have radiated independently into similar ecological niches on each island of the Greater Antilles. However, Anolis lizards on the mainland of Central and South America have undergone an equally spectacular adaptive radiation, occupying similar ecological niches but without converging onto the same morphologies. Why mainland species have not converged on similar morphologies has remained unclear, but differences in predation pressure, competition, and behavior have been suggested. However, tests of these hypotheses have not been conducted due to a lack of quantitative ecological, morphological, behavioral, and performance data. Here we provide such data for 21 species of Anolis from Central and South America to explore ecomorphological relationships among mainland anoles. Our data suggest that differences between mainland and Caribbean Anolis are not a consequence of insularity per se, but rather indicate basic differences in ecomorphological relationships on the mainland versus the Greater Antilles.
Contact person: S. Greif
02/11/09.Prof Dr Walter Salzburger. Evolution in Darwin's Dreamponds: The adaptive radiations of cichlid fishes in East Africa
University Basel, Switzerland
Website: http://www.evolution.unibas.ch/salzburger/
Abstract: As many as 150 years after the publication of Charles R. Darwin’s The Origin of Species, the identification of the processes governing the emergence of novel species remains a fundamental question to biology. Why is it that some groups have diversified in a seemingly explosive manner, while other lineages have remained unvaried over millions of years? And what are the external factors and environmental conditions that promote diversification? A key to these and related questions is the comparative study of exceptionally diverse yet relatively young species assemblages that have radiated in geographically well-defined areas, such as the Darwin’s finches on the Galapagos archipelago, the Caribbean Anoles lizards or the cichlid fishes in the Great Lakes of East Africa. Lakes Tanganyika, Malawi, and Victoria are each teeming with a unique set of hundreds of endemic cichlid species, which are likely to have evolved in the last few millions to several thousands of years only. East Africa’s cichlid species differ greatly in ecologically relevant, hence naturally selected, characters such as mouth morphology and body shape, but also in sexually selected traits such as coloration. One of the most fascinating aspects of cichlid evolution is the frequent occurrence of evolutionary parallelisms, which has led to the question whether selection alone is sufficient to produce these parallel morphologies, or whether a developmental or genetic bias has influenced the direction of diversification.
09/11/09. Dr Angus Buckling. Antagonistic coevolution between bacteria and viruses
University of Oxford, UK
Website: http://www.zoo.ox.ac.uk/staff/academics/buckling_agj.htm
Abstract: Host-parasite antagonistic coevolution has potentially massive implications for a range of ecological and evolutionary processes. Microbes are particularly useful for studying coevolution, because of the speed at which their evolution can occur. I will describe experiments that attempt to identify the ecological and genetic drivers and consequences of coevolution, in both laboratory and natural communities of bacteria and their parasitic viruses.
16/11/09. Dr Sergey Nuzhdin. Genomics approaches to study adaptation
University of Southern California, USA
Website: http://nlab.usc.edu/drupal/user/5
Abstract: Genetic variation results in phenotypic variation through the in-between-ome: epigenetic modification, transcript metabolism, and protein networks. Some network structures might hide genetic imperfections, resulting in a larger amount of maintained variation; while others expose it, resulting in stronger conservation. These pathways are also reshuffled during adaptation of populations to local environments. Here, genomics tools will be used to assess how genetic variation is shaped by the network structures, and how it is rearranged in populations during local adaptation. The interpretative focus will be on transcription networks. The data and examples will be sampled from Drosophila, Arabidopsis, and Medicago research
Contact person: Forschergruppe
23/11/09. Dr Sven Bacher. General Patterns in Biological Invasions
University of Fribourg, Switzerland
Website: http://www.unifr.ch/biol/ecology/bacher/
Abstract: Alien invasive species are a large threat to biodiversity (Mack et al. 2000; IUCN 2009), and the economic damage they cause exceeds 5% of the global gross product (Pimentel 2002). Although there is a general consensus that the overall negative effects of alien species have to be reduced, strategies on how to do this effectively with a limited budget and which species should be targeted first are controversial matters. One promising way to address the problem is to prioritize actions against alien species that cause the highest level of impact or to prevent species with a high impact potential from becoming established or spreading. Thus, what is needed are methods to predict which species are transported and released, which of these then have a high potential to establish, spread and cause serious damage. This is not an easy task, because it requires comparisons among species with different phylogenetic and geographical origins. In my talk I will outline pitfalls in such comparisons and show some recent advances in invasion theory and statistics on how to avoid them. I will use examples from different taxonomic groups, but will concentrate mainly on insects and mammals.
Contact person: J. Jeschke
07/12/09. Dr Artyom Kopp.How the fly got its sexy legs. The origin and evolution of Drosophila sex combs
University of California, Davis, USA
Website: http://www.eve.ucdavis.edu/kopplab/
Abstract: The sex combs of Drosophila are a recent evolutionary innovation.This male-specific structure is used by males during courtship and is important for mating success. Sex combs show rapid evolutionary diversification and many instances of convergent evolution. We have shown that nearly identical adult structures can develop using entirely different cellular mechanisms. Sex comb evolution was associated with the origin of novel and previously undocumented interactions between HOX and sex determination genes. Activity of the sex determination pathway was brought under the control of the HOX code to become segment-specific, while HOX gene expression became sexually dimorphic. At the same time, both HOX and sex determination genes were integrated into the intrasegmental spatial patterning network, and acquired new joint downstream targets. Together, these changes reflect the assembly of a novel sex-specific developmental pathway under sexual selection.
Contact person: Forschergruppe
14/12/09. Dr Hideki Innan. Coevolution of Duplicated Genes by Gene Conversion
Graduate University for Advanced Studies, Hayama 240-0193, Japan
Website: http://www.sendou.soken.ac.jp/esb/innan/InnanLab/Index_En.html
Abstract: Concerted evolution is a phenomenon that copy members in a multigene family coevolve by exchanging their DNA fragments. Gene conversion should be responsible for this process in a small multigene family or duplicated genes. Recent genomic surveys demonstrate that concerted evolution by gene conversion is quite common in various species, indicating an important role of gene conversion in the early stages of the evolution of duplicated genes. Here, I will introduce our continuing research on gene conversion in duplicated genes. The topics include: - Genome-wide demonstration of the impact of gene conversion in duplicated genes. - Development of basic theories on single nucleotide polymorphisms (SNPs) in duplicated genes. - Modeling the nucleotide divergence between duplicated genes under concerted evolution. - Selection operating for and against gene conversion.
Contact person: Forschergruppe
18/01/10. Dr Evelyne Heyer. Social behaviour, lifestyle and genetic diversity in human populations
MNHN/CNRS Paris, France
Website: http://www.ecoanthropologie.cnrs.fr/spip.php?article300
Abstract: Cultural practices such as social organization and lifestyle in human populations can affect both Intra and Inter population genetic diversity. I will present results of two of our field studies, one in Central Africa where Pygmies hunter-gatherers coexist with neighbouring farmers, one in Central Asia where nomadic herders coexist with farmers. The ways in which individuals choose their mates and where they settle are known to affect the genetic diversity inside population and between populations. In this context, I will highlight the impact of the social organization of herders from Central Asia into patrilineal descent groups on their neutral genetic diversity. I will also present some of our work on the genetic adaptation to different lifestyles, focusing on diet adaptation. Regarding the Pygmies from Central Africa, I will present our recent studies of the population history of this group and show how this information can be used to demonstrate that genetic factors are involved in the short height of Pygmies.
25/01/10. Dr Oscar Gaggiotti. Disentangling the effects of evolutionary, demographic and environmental factors influencing the genetic structure of natural populations
University of Grenoble, France
Website: http://www-leca.ujf-grenoble.fr/membres/gaggiotti.htm
Abstract: The spatial structuring of intraspecific genetic diversity is the result of random genetic drift, natural selection, migration, mutation, and their interaction with historical processes. The contribution of each has been typically difficult to estimate, but recent advances in statistical genetics have provided valuable new investigative tools to tackle such complexity. During the talk I will explain how we can capitalise on such advances in order to develop a statistical framework that allows us to disentangle the effects of selective forces and demographic processes. The use of this framework will be illustrated with an application to the study of a widely distributed and abundant marine pelagic fish of economic importance, Atlantic herring (Clupea harengus)
Contact person: Forschergruppe
01/02/10. Prof.Dr Christoph Scheidegger. Dispersal and estabishment of a lichen symbiosis: patterns and processes at the landscape level
ETH/WSL Zurich, Switzerland
Website: http://www.wsl.ch/personal_homepages/scheideg
Lichens reveal various reproductive strategies where the mycobiont and its photobionts either disperse separately, in the case of sexual reproduction (horizontal transmission of photobionts) or where the lichen symbionts are codispersed with clonal, symbiotic propagules (vertical transmission of photobionts). With a few exceptions, where photobionts grow between the meiosporangia of the mycobiont and are codispersed with the ascospores, sexual reproduction is always associated with horizontal transfer of photobionts. Clonal propagules are generally relatively large and are likely to have a more limited dispersal range than the sexual propagules. Several lichen species including Lobaria pulmonaria reproduce both with vegetative and sexual diaspores.
Dispersal is the precondition for new habitats to be occupied, for habitat patches of a metapopulation to get colonised and for new populations to be founded. Some tree colonising lichen species reproducing with large propagules have been suggested to be dispersal limited. Such species are often restricted to old-growth sites and forests with a low disturbance regime und thus threatened in many parts of their distribution area. Establishment, i.e. the post-dispersal processes that involve adhesion, attachment and morphogenesis to a juvenile thallus that shows chemical and physiological properties of an adult thallus, is equally important as dispersal for a species to be successful at colonising new sites and for its long-term persistence. I will present recent studies on how disturbance at different spatial scales influence abundance, genetic diversity and dispersal range of the threatened forest –dwelling lichen species Lobaria pulmonaria.
Contact person: A. Beck
