Year: 2013
Type: dissertation
Abstract: Yhteenveto: Populaation syklisyyden ja eristyneisyyden vaikutuksista geneettiseen monimuotoisuuteen Diss.Genetic diversity within natural populations is essential for populations' vitality, adaptation and evolution.Small population size, population isolation, and fragmentation are potential risks of losing genetic variability.Also cyclic population dynamics can cause the loss of genetic diversity because of reductions in population size.Lowered genetic diversity often translates to decreased fitness of individuals.In this thesis I aimed to study the maintenance of genetic diversity in the contexts of population dynamics and fragmentation.More specifically, I examined if frequent population crashes and fragmentation affect genetic diversity, how it is maintained (especially the role of density-dependent selection), and how it is translated to individual fitness.I assembled a panel of genetic markers for a cyclic rodent, the bank vole (Myodes glareolus).The panel consisted of anonymous, expressed sequence taglinked and social behavior-associated (vasopressin and oxytocin-linked) microsatellite loci.I used long-term data to see if genetic diversity was maintained within a population and if density-dependent selection was affecting on social behaviorassociated loci.I also contrasted mainland and island populations to examine if fragmentation had reduced their genetic diversity.Finally, I studied whether lowered genetic variability translated to decreased fitness of individuals.I found that genetic variability was maintained within populations despite the frequent crashes in population size.Genetic diversity was presumably promoted by high effective population size and migration, and density-dependent selection did not substantially act on those social behavior-associated loci.Furthermore, my research showed that population fragmentation was associated with reduced genetic diversity of females, and, surprisingly, the females with lower genetic diversity gained fitness benefit.Taken together, this thesis hopes to bring new insights into the associations between population size, population isolation and genetic diversity.It shows that the genetic diversity might bear both positive and negative effects on individual fitness.Moreover, it suggests that cyclic population dynamics do not provoke density-dependent selection on social behavior-associated loci.
Author: Kaisa Rikalainen
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2267513138