Abstracts (first author)
Genetic signature of local adaptation of MHC genes to varying parasite pressures
Author(s): Eizaguirre C, Lenz TL, Kalbe M, Milinski M
Although crucial for the understanding of adaptive evolution, genetically resolved examples of local adaptation are rare. To maximize survival and reproduction in their local environment, hosts should resist their local parasites and pathogens. The major histocompatibility complex (MHC) with its key function in parasite resistance represents an ideal candidate to investigate parasite-mediated local adaptation. Using replicated field mesocosms, stocked with second-generation lab-bred three-spined stickleback hybrids of a lake and a river population, we show local adaptation of MHC genotypes to population-specific parasites, independently of the genetic background. Furthermore, the multi-locus specificity of MHC genes revealed that increased individual allele divergence of lake MHC genotypes allows lake fish to fight the broad range of lake parasites, whereas more specific river genotypes confer selective advantages against the less diverse river parasites. Such results demonstrate that not only the presence of given alleles is important for local adaptation but also that the combinations of alleles on the different duplicated loci are crucial for host-parasite coevolution.