Microsatellite markers confirm extensive population fragmentation of the endangered Balkan palaeoendemic Martino's vole (Dinaromys bogdanovi)

The Martino's vole is an endangered rodent endemic to the western Balkan Peninsula. Its range is fragmented, and populations are small due to high habitat specificity. The level of genetic variation within such populations is often low, and genetic differentiation between patchily dispersed populations is high. By scoring eight microsatellite loci in 110 individual Martino's voles originating from 27 locations throughout the species range, we analysed genetic variation at both the intra- and interpopulation level. Factorial correspondence analysis, Bayesian analyses, and allele sharing distances divided individuals into three phylogroups (Northwestern, Central, and Southeastern), thus providing independent support for phylogeographic structuring, a pattern that has been described in previous studies based on mitochondrial DNA. Spatial genetic analyses showed that populations are highly fragmented, even in those areas with the highest population densities. The highest intrapopulation genetic variability and stable effective population sizes were found in Mount Zelengora (Bosnia and Herzegovina), which harbours a relatively large population of Martino's voles. Populations in the Central and Southeastern lineages exhibited a significant isolation-by-distance pattern, indicating limited gene flow between them. Contrary to previous opinion, low effective population size and very limited gene flow between remaining populations suggest that the long-term existence of the Martino's vole might not be secure, even in populations that live in optimal habitats. The only threat to the Martino's vole identified thus far is competitive exclusion by the European snow vole. However, our results suggest that conservation problems associated with this paleoendemic rodent are more complex.