Evolutionary forces shaping innate immune gene variation in a bottlenecked population of the Seychelles warbler
Year: 2015
Type: dissertation
Abstract: In this thesis, I investigated different evolutionary forces in shaping genetic variation within \na bottlenecked population of an island species, the Seychelles warbler (Acrocephalus \nsechellensis). I specifically explore pathogen-mediated selection within this system by using \navian beta-defensins and toll-like receptor genes to examine functional variation. First, I \ncharacterise variation within both gene groups in this population and show that this species’ \ndemographic history has had an overriding effect on selection and random drift is the \npredominant evolutionary force. I characterise variation within these gene groups across \nseveral other Acrocephalus species, in addition to looking at a specific locus in a prebottlenecked \npopulation in order to directly compare genetic variation pre- and postbottleneck. \nI use population genetic statistical methods to detect selection at several \npolymorphic genes and evaluate the robustness of these methods when applied to singlelocus \nsequence data, which may be lacking in power and not meet the demographic \nassumptions that come with these tests. To overcome this, I designed forward-in-time \nsimulations based on microsatellite markers used in pre- and post-bottleneck populations of \nthe Seychelles warbler. I am able to delineate the evolutionary effects of selection from drift \nand show that some toll-like receptor genes are indeed under positive balancing selection in \nspite of the recent bottleneck. I further explore how this variation is maintained by \nconducting association analyses investigating innate immune gene variation and its \nrelationship with individual survival and malarial susceptibility / resistance. Environmental \nfactors are also considered. By investigating the consequences of functional variation in a \nbottlenecked species we are able to assess its long-term viability and adaptive potential, \nwhilst elucidating the evolutionary importance of maintaining genetic variation in natural \npopulations.
Author: Danielle L. Gilroy
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2473090445