The phylogeographical and population genetic approach to the investigation of the genetic diversity patterns in self‐incompatible clonal and polyploid Linnaea borealis subsp. borealis

Surveys of genetic diversity patterns of self‐incompatible clonal polyploid plant species are still scarcer than those of diploid plant species. Therefore, I studied the phylogeographical history of Linnaea borealis subsp. borealis to shed light on the colonization history of this clonal self‐incompatible polyploid plant in Eurasia using selected regions of plastid DNA and genetic diversity patterns of 22 populations of this species employing AFLP markers. I also addressed the question of whether the genetic diversity patterns in L. borealis subsp. borealis in Eurasia are similar to those of earlier published studies of clonal self‐incompatible diploid or polyploid plants. This survey revealed that the shallow phylogeographical history (six plastid haplotypes forming one haplogroup, 100% bootstrap support) and moderate genome‐wide diversity estimated using AFLP markers (Frag_poly = 10.8–38.9%, I = 0.060–0.180, F_ST = 0.289) were general characteristics of L. borealis subsp. borealis in its Eurasian range. The sampling strategy, in most cases at 1–2‐m or even 3–5‐m intervals, showed that a balance between vegetative and sexual reproduction and limited pollen dispersal among compatible mates can be important for genetic diversity patterns in populations of this taxon. Despite the fact that one‐half of the investigated populations were strongly isolated, they still preserved similar levels of genetic diversity across the geographical range. I found no support for the hypothesis that a bottleneck and/or inbreeding had accompanied habitat fragmentation as factors shaping genetic diversity. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 64–76.