Evolutionary and conservation genetics of the Seychelles warbler (Acrocephalus sechellensis)
Year: 2014
Type: dissertation
Abstract: In this thesis, I investigated how evolutionary forces and conservation action interact to shape \nneutral and adaptive genetic variation within and among populations. To accomplish this, I \nstudied an island species, the Seychelles warbler (Acrocephalus sechellensis), with \nmicrosatellite markers and major histocompatibility complex (MHC) genes as measures of \nneutral and adaptive variation respectively. First, I used museum DNA and historical records to \nreveal a recent bottleneck that provides context for the contemporary genetic variation \nobserved in this species. I then determined the impact of four translocations on genetic \ndiversity over two decades. I found that diversity does not differ significantly between islands \nbut the use of smaller founder sizes in two translocations has caused population divergence. \nThese results indicate that stochastic genetic capture is important in translocations and that \nfuture assisted gene flow between populations may be necessary. As a tool for conservation \npractitioners, I wrote a technical report of the most recent translocation - to Frégate Island - \ndetailing practicalities and outcomes to help inform future translocation policy. Using two \ntranslocation events as experiments, I then tested whether MHC-based social mate choice acts \nto maintain MHC diversity in the Seychelles warbler, finding that male age and heterozygosity, \nbut not MHC, predicted pairing success. Lastly, I investigated survival and reproductive \nconsequences of Ase-ua4, an MHC class I allele previously shown to confer a survival \nadvantage in the Seychelles warbler. I found widespread patterns of allele frequency increase \nwithin cohorts consistent with the survival effect, but no overall increase in population allele \nfrequency over time. I investigated potential antagonistic reproductive mechanisms, but found \nno clear evidence for why this allele is not driven towards fixation. Collectively, my results \nprovide an interesting case study of the evolutionary conservation approach, whilst providing \ninsight into the importance of maintaining genetic variation in natural populations.
Author: David Wright
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2036335764