Recombination, Diversity and Differentiation at the MHC-B Region in Two Populations of Black Grouse (Tetrao tetrix)
Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
The genes of the major histocompatibility complex (MHC) encode proteins that are involved in the adaptive immune system. They are among the most polymorphic genes known in vertebrates and are mainly responsible for the presentation of antigens to T-cells in order to initiate an immune response. Evidence indicates that balancing selection is behind this extraordinary polymorphism. Known for it’s more compact and streamlined organization black grouse and other galliform birds have what is called a minimal essential MHC. Here, I investigate the patterns of recombination and linkage disequilibrium, genetic diversity, differentiation and signs of positive natural selection in two demographically distinct populations of black grouse (Tetrao tetrix). Using MHC linked microsatellites and MHC-BLB single locus sequences I showed that a small isolated population from the Netherlands is significantly differentiated from a large population from Finland , that the Dutch population has lower levels of genetic variation and a smaller number, but more divergent BLB alleles. Both populations also show signs of historical balancing selection acting on the codons responsible for the antigen binding site of the BLB genes. Lastly, the Dutch population shows overall signs of higher linkage disequilibrium resulting in lower population recombination rates compared to the Finnish population. Based on the estimated ratio between the population recombination rate and the population mutation rate I showed that mutations have been more prevalent in shaping diversity at the black grouse MHC-B region than recombination has been. The differences in variation, selection and recombination between the Dutch and Finnish population are likely a reflection of their very different demographic histories.
Place, publisher, year, edition, pages
2014. , 28 p.
MHC, genetic variation, recombination, linkage disequilibrium, conservation, black grouse, Tetrao tetrix
IdentifiersURN: urn:nbn:se:uu:diva-236226OAI: oai:DiVA.org:uu-236226DiVA: diva2:763570
Master Programme in Biology
Höglund, Jacob, ProfessorMeyer-Lucht, Yvonne, PhD
Brunberg, Anna-Kristina, Universitetslektor