Do rivers and human-induced habitat fragmentation affect genetic diversity and population structure of the European ground squirrel at the edge of its Pannonian range?

The European ground squirrel (EGS) (Spermophilus citellus) populations of Vojvodina (Serbia) represent the southernmost part of its distribution in the Pannonian lowland. For species with low dispersal abilities a presence of even weak barriers can have significant influence on genetic structure among adjacent populations. We examined here the effects of habitat fragmentation and river barriers on the genetic structure of the EGS based on 12 microsatellite loci. Bayesian clustering methods were used as additions to classical population genetic approaches. We found that EGS populations in Vojvodina are highly fragmented, but their genetic variation is still higher than in peripheral populations in Central Europe. Populations in Vojvodina consistently grouped into three genetic clusters. The Danube, but not the Tisza River, represents an important barrier to gene flow. EGS populations in the studied area did not show the signs of recent genetic bottlenecks, as would be expected from observations of recent population declines. Conservation strategy should be focused on maintenance of remained suitable habitats and optimal population sizes.