In preliminary investigations I have shown that Eurasian perch (Perca fluviatilis L.) of Lake Constance that form local aggregations with kin can olfactory discriminate between kin and non-kin, and additionally between the own and a foreign population that lives in sympatry within the same lake. Specific allelic compositions at MHC (major histocompatibility complex) genes have been shown to play a major role in kin recognition and to influence mate choice decisions in a variety of vertebrate species, including freshwater fishes, by affecting the individual body odour. In this project I want to investigate the role of MHC genes for kin- and population recognition. First, I will test if perch differentiate individuals by "family specific" MHC alleles learned by phenotype matching and use this information for kin recognition. Secondly I develop and test a new hypothesis that kin recognition could be the basal mechanism from which olfactory based population recognition may have derived. There I would show that in species using chemical communication for social interactions like e.g. kin recognition, MHC genes that determine specific odours could be under strong disruptive selection during the speciation process. This could lead to "population specific" MHC genes that can be used to olfactory discriminate between populations and drive reproductive isolation. Molecular genetic investigations about differences in the individual composition of specific MHC alleles within and between the coexisting perch populations of Lake Constance will be combined with behavioural experiments for MHC-mediated kin- and population recognition and mate choice strategies.
