Is the Gibraltar Strait a barrier to gene flow for the bat Myotis myotis (Chiroptera : Vespertilionidae)?

Because of their role in limiting gene now, geographical barriers like moun tains or seas often coincide with intraspecific genetic discontinuities. Al though the Strait of Gibraltar represents such a potential barrier for both plants and animals, few studies have been conducted on its impact on gene now. Here we test this effect on a bat species (Myotis myotis) which is app arently distributed on both sides of the strait. Six colonies of 20 Myotis myotis each were sampled in southern Spain and northern Morocco along a lin ear transect of 1350 km. Results based on six nuclear microsatellite loci r eveal. no significant population structure within regions, but a complete i solation between bats sampled on each side of the strait. Variability at 60 0 bp of a mitochondrial gene (cytochrome b) confirms the existence of two g enetically distinct and perfectly segregating clades, which diverged severa l million years ago. Despite the narrowness of the Gibraltar Strait (14 km) , these molecular data suggest that neither males, nor females from either region have ever reproduced on the opposite side of the strait. Comparisons of molecular divergence with bats from a closely related species (M. blyth ii) suggest that the North African clade is possibly a distinct taxon warra nting full species rank. We provisionally refer to it as Myotis cf punicus Felten 1977, but a definitive systematic understanding of the whole Mouse-e ared bat species complex awaits further genetic sampling, especially in the Eastern Mediterranean areas.