A rapid population expansion retains genetic diversity within European rabbits in Australia.

The well documented historical translocations of the European rabbit (Oryctolagus cuniculus) offer an excellent framework to test the genetic effects of reductions in effective population size. It has been proposed that rabbits went through an initial bottleneck at the time of their establishment in Australia, as well as multiple founder events during the rabbit's colonization process. To test these hypotheses, genetic variation at seven microsatellite loci was measured in 252 wild rabbits from five populations across Australia. These populations were compared to each other and to data from Europe. No evidence of a genetic bottleneck was observed with the movement of 13 rabbits from Europe to Australia when compared to French data. Within Australia the distribution of genetic diversity did not reflect the suggested pattern of sequential founder effects. In fact, the current pattern of genetic variation in Australia is most likely a result of multiple factors including mutation, genetic drift and geographical differentiation. The absence of reduced genetic diversity is almost certainly a result of the rabbit's rapid population expansion at the time of establishment in Australia. These results highlight the importance of population growth following a demographic bottleneck, which largely determines the severity of genetic loss.