Applicability of rabbit microsatellite primers for studies of hybridisation between an introduced and a native hare species.

Introduced species may hybridise with relatives in the native fauna or flora and thereby compete for matings and transmit alien DNA. Such interference may contaminate unique genepools, disturb existing ecological balances and may ultimately result in the extinction of the native species. In Sweden, the introduced brown hare (Lepus europaeus Pall.) hybridise with the native mountain hare (L. timidus L.), both relatively common members of the present Swedish fauna. This hybridisation has resulted in the transmission of mitochondrial DNA from the mountain hare to the brown hare, but absence of species differences in karyotype and allozymes have prevented investigations of the amount of nuclear gene flow. More polymorphic genetic markers are needed to analyse evidence of hybridisation in the nuclear genome. The conservation of microsatellite loci across taxa usually enables PCR amplification of microsatellites in closely related species with the same primers. We have used five microsatellite primer pairs, developed for the European wild rabbit (Oryctolagus cuniculus L.) to amplify microsatellites in the two species of hare in Sweden. The obtained allelic variation was used to construct a genetic distance tree based on the amount of shared alleles between all pairs of individuals (shared-allele index). This method offered sufficient differences to arrange all individuals in two groups, one for each species. Identification of individual hybrids based on the number of alleles shared between the species is not possible with these five microsatellite markers.