A population genetic study in a scattered forest species (Sorbus torminalis (L.) Crantz) using RAPD markers

Wild service tree [Sorbus torminalis (L.) Crantz] is a forest tree widespread in Europe, characterized by a scattered distribution. Its hermaphroditic flowers are pollinated by insects, and outcrossing is the preminent mating system, also due to the presence of gametophytic self-incompatibility. Genetic diversity and differentiation of 22 populations from north-western Italy were investigated by means of variation scored at 53 polymorphic RAPD (Random Amplified Polymorphic DNA) loci. Populations differed in genetic variation, with Shannon diversity index ranging from 0.166 to 0.469. According to Analysis of Molecular Variance (AMOVA), most of the genetic variation was found within populations (61.78%) with a significant proportion of variance attributable to genetic differences between regions (23.60%) and between populations (14.62%). Evidence for isolation by distance was found in the set of populations sampled. The effect of habitat fragmentation on genetic variation was also evaluated. The efficacy of RAPD markers in analysing genetic variation, and the contribution of the results in terms of the preservation of biodiversity, are discussed.