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 recolonization 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 previously glaciated region of Scotland. These results were compared with existing data on south-western continental populations. Low genetic differentiation (FST = 0.024) and lack of consistent geographical pattern were found at the regional level among Scottish populations, implying a high rate of gene flow (Nm = 10.2), probably favoured by the nearly continuous range of C. vulgaris across Scotland and characteristics of the Scottish environment. Scottish populations possessed lower mean allozymic diversity (PLP = 40.48, A = 1.95, He = 0.133) than populations from all the continental regions investigated 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 revealed by palynological data.