Title: The effects of epistasis and linkage on the invasion of locally beneficial mutations
Abstract: This talk is mainly based on recent joint work with Martin Pontz, in which we studied local adaptation of a peripheral population by investigating the fate of new mutations using a haploid two-locus two-allele continent-island migration model. We explored how linkage, epistasis, and maladaptive gene flow affect the invasion probability of weakly beneficial de-novo mutations that arise on the island at an arbitrary physical distance to a locus that already maintains a stable migration-selection polymorphism.
By assuming a slightly supercritical branching process, explicit conditions were deduced on the parameters that permit a positive invasion probability and approximations for the invasion probability were derived. These approximations together with empirically motivated distributions of additive and epistatic effects can be used to analyze the influence of epistasis on the expected invasion probability if mutants are drawn randomly from such a distribution and occur at a random physical distance to the existing polymorphism. We founnd that the invasion probability generally increases as the epistasis parameter increases or the migration rate decreases, but not necessarily as the recombination rate decreases. These results were used to predict the size of emerging 'genomic island of local adaptation' by exploring the size of the chromosomal neighborhood of the already established polymorphism in which 50% or 90% of the successfully invading mutations become established.
About Reinhard Bürger: https://homepage.univie.ac.at/reinhard.buerger/
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