Absence of geographic structure in Rubus using chloroplast DNA microsatellites.

Twenty populations of the species aggregate Rubus fruticosus were collected throughout European natural forests and analyzed by chloroplast microsatellites (SSR). Results showed high genetic diversity (hT = 0.73) and haplotipic richness (17 haplotypes were detected), and the presence of several unique alleles. The value of genetic differentiation between populations was low for unordered alleles (GST = 0.29) and for ordered alleles (NST = 0.30), revealing the absence of phylogeographic structure of the haplotypic diversity. This can be mainly ascribed to the mechanisms of seed dispersal, mostly mediated by animal ingestion, which are responsible for a efficient gene flow through seeds. Rubus L. species are characterized by the ability to colonizing disturbed, but also intact forest communities, rapidly propagating though suckering and hybridizing with native species. Our results suggest that efficient seed dispersal can counterbalance the effects of vegetative propagation, maintaining a high genetic diversity.