DFG FOR 1078 Natural Selection in Structured Populations

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Seminars 2009

18/05/09 - Prof. John Kelly - "The maintenance of genetic variation in quantitative traits: Results from the yellow monkeyflower"

Dept. of Ecology and Evolutionary Biology, University of Kansas

kellyAbstract: A balance of evolutionary forces--mutation, selection, drift, and gene flow--maintains quantitative trait variation within populations. For a variety of questions, it is essential to understand whether natural selection is mainly purifying (acts to eliminate variation) or balancing (acts to maintain polymorphisms). Our group uses a combination of genomic and biometric techniques to investigate quantitative trait variation in the yellow monkeyflower, Mimulus guttatus. Thus far, the accumation of evidence from a variety of experiments indicates that natural selection likely maintains a large fraction of the standing genetic variation in floral morphology, development rate, and male fitness components.

25/05/09 - Prof. Andrea Betancourt - "Recombination and adaptation in the Drosophila genome"

University of Edinburgh

betancourtAbstract: In anisogamous organisms, sex carries a cost: every sexually reproducing female must produce two offspring to maintain a stable population size, while asexual females only need to produce one (Maynard Smith, 1978). In spite of this cost, sexual reproduction is widespread. * *One possible explanation is that recombination is advantageous, as it allows selection to act on alleles independently. If so, the advantage of recombination may be evident within genomes, by contrasting regions with different levels of recombination. I will discuss patterns of protein polymorphism and divergence in high vs. low recombination regions of the /Drosophila /genome. These patterns reveal that both purifying and positive selection are impaired in low recombination regions.

06/07/09 - Prof. Mark Beaumont - " Likelihood-free inference of local selection"

University of Reading, UK

beaumontAbstract: Approximate Bayesian computation (ABC) has proved useful for complex models in which the likelihood function is difficult or expensive to obtain. This approach typically requires the data to be compressed into summary statistics. In a hierarchical setting one may be interested both in hyper-parameters and parameters, and there may be very many of the latter - for example, in a genetic model, these may be parameters describing each of many loci or populations. This poses problems for ABC in that one then requires summary statistics for each locus and/or population with concomitant problems of scaling. We develop a general method for addressing these problems efficiently, and we describe recent work in which the ABC method can be used to detect loci under local selection. Authorship: Eric Bazin (CIRAD, Montpellier), Kevin Dawson (Rothamsted Research), Mark Beaumont (University of Reading)top

20/07/09 - Prof. Alistair McGregor - " Investigating the genetic basis of morphological variation within and between Drosophila species"

Institute for Population Genetics, University of Veterinary Medicine Vienna

mcgregorAbstract: In the last 10 years there has been much progress in understanding the genetic basis of morphological variation among species. However, there are three areas that need to be further addressed to test current models and give a more complete picture of morphological evolution: What is the genetic basis of differences in quantitative traits such as organ shape and size? What evolutionary forces have shaped morphological differences? To what extent does standing genetic variation contribute to differences between species? I will discuss ongoing projects in my lab investigating the evolution of eye size and trichome patterns within and among Drosophila species that aim to address these questions.

16/11/09 - Dr. Sergey Nuzhdin - "Genomics approaches to study adaptation"

University of Southern California, USA

nuzhdinAbstract: 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

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

koppAbstract: 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.top

14/12/09 - Dr. Hideki Innan - "Coevolution of Duplicated Genes by Gene Conversion"

Graduate University for Advanced Studies, Hayama 240-0193, Japan

innanAbstract: 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.