Proximal causes of genetic variation between and within populations of rauli (Nothofagus nervosa)
Random Amplified Polymorphic DNA(RAPD)markers were used to assess the genetic diversity of 587 individuals, belonging to 22 populations of Nothofagus nervosa that were distributed through the Coastal (38°S to 41 °S) and Andes Mountains in Central-Southern Chile (36°S to 40°S). The objective of this study was to complement the genetic inferences previously determined by isozyme analysis, in order to obtain more accurate genetic diversity estimations. We scored 81.8% of the polymorphic loci of the samples tested. The average incidence of genetic polymorphism within populations was high, with values ranging between 33% and 63%. Analysis of molecular variance (AMOVA) showed most of the genetic variation was distributed within populations (87.6%), but FST values (FST = 0.124; p< 0.00001) indicated that there was also a significant difference among populations. A discriminant analysis revealed three geographically defined groups and showed that 14 loci explained 87.2% of the genetic differentiation among N. nervosa populations. Watterson's neutrality test and Ohta's two-locus analysis of linkage disequilibrium (LD) both suggested that stochastic demographic and environmental factors can partially explain the loci variation observed in the RAPDs. The role of the last glaciations, as well as some conservation and breeding strategies, may have influenced current genetic variation and fragmentation in this species.