Molecular diversity usually decreases with distance from potential refugia, and species with low population size and a scattered nature are expected to have relatively low genetic diversity. George et al. study one of the rarest deciduous tree species in Europe, Sorbus domestica, across its entire distribution and find unexpectedly high levels of molecular diversity within populations irrespective of whether they are located in the south or close to the northern distribution limit of the species. The presence of large population genetic clusters suggests that long-distance gene flow at the landsacpe scale together with molecular mechanisms that helped prevent inbreeding are responsible for the observed pattern.
Unexpectedly high levels of molecular diversity are found within populations of Sorbus domestica, irrespective of their location.