Allozyme variation and genetic structure of Calluna vulgaris (heather) populations in Scotland: the effect of postglacial recolonization

Recent fragmentation of populations as well as historical postglacial recol onization may have significantly affected the population genetic diversity of temperate plant species. Regional allozymic variability was measured at seven loci within and among 12 populations of Calluna vulgaris in the previ ously glaciated region of Scotland. These results were compared with existi ng data on southwestern continental populations. Low genetic differentiatio n (F-ST = 0.024) and lack of consistent geographical pattern were found at the regional level among Scottish populations, implying a high rate of gene (Nm = 10.2), probably favoured by the nearly continuous range of C. vulgar is across Scotland and characteristics of the Scottish environment. Scottis h populations possessed lower mean allozymic diversity (PLP = 40.48, A = 1. 95, H-e = 0.133) than populations from all the continental regions investig ated previously. Belgian populations were genetically more closely related to Scottish than to other continental populations. These last two findings are interpreted with regard to the evolutionary history of the species reve aled by palynological data.