Genetic differentiation among stationary and anadromous perch (Perca fluviatilis) in the Baltic Sea

Perch (Perca fluviatilis L.) in the Baltic sea region display three major r eproductive behavioural patterns; perch that live in the brackish environme nt but migrate to freshwater in the spring in order to spawn (anadromous pe rch), stationary perch living and breeding in the brackish sea (sea perch), and lake perch living and breeding in freshwater lakes (lake perch). We ha ve compared four different perch populations from the northern part of the Gulf of Bothnia (Umea, Sweden), representing two anadromous populations, on e lake population and one brackish sea population. The lake is isolated fro m the Gulf of Bothnia due to elevation of shorelines during the last 100 ye ars. This short time of isolation provides an opportunity to study the very early stages of population differentiation. Genetic differentiation of pop ulations was analysed using mtDNA D-loop sequence polymorphism and RAPD's. Both the mtDNA and the RAPD data revealed highest level of genetic differen tiation between the reproductive behavioural forms from around Umea. Furthe rmore, AMOVA and Chi-square analyses of the mtDNA haplotypes revealed relat ively high level of differentiation of the lake perch population given the short time of isolation.