Study area and roe deer sampling in northeastern Poland.

Samples were collected in and around three lowland forests: Augustów (A), Knyszyn (K) and Białowieża (B). Filled symbols indicate samples that were genotyped at both microsatellites and mtDNA control region, whereas open symbols indicate samples that were only typed with microsatellites. Polygons were drawn around regions with contrasting degrees of forest cover within each sampling site, which were used to define field (O - open habitat) and forest (F) groups of roe deer; a further subdivision in Białowieża separates open habitats in the north (N) and south (S) of a main road.