Genetic structure of fragmented populations of red squirrel (Sciurus vulgaris) in the UK

The relationships among 207 squirrels from 12 locations in the UK and three in mainland Europe were examined using mitochondrial DNA (mtDNA) control r egion sequence. Twenty-six haplotypes were detected, many of which were pop ulation specific. Eighty per cent of the populations analysed contained two or more haplotypes. Hierarchical analysis of molecular variance showed the majority of genetic variation to be partitioned among populations. Genetic diversity varied considerably within the UK, and conformed to no obvious g eographical trend. The populations in Argyll and Spadeadam Forest showed th e highest levels of variation in the UK. However, the greatest genetic dive rsity was seen in Bavaria, southern Germany where six unique alleles were d etected in a sample of 10 individuals. Phylogenetic analysis revealed no ev olutionary divergence between UK and mainland European haplotypes. We concl ude that, within the UK,the genetic patterns observed are most likely to be explained by the effects of genetic drift which has occurred since the iso lation of populations during the past few hundred years, hence we cannot de tect any underlying phylogeographic pattern. Therefore, the use of larger, geographically distinct populations within the UK for augmentation of small isolated populations is unlikely to pose problems of genetic incompatibili ty. Further, the role that demographic factors may have in complicating the application of current genetically based management unit criteria is likel y to need further attention.