Allozyme variation of European Black (Pinus nigra Arnold) and Scots pine (Pinus sylvestris L.) populations and implications on their evolution: A comparative study

A comparative study of the type, magnitude, and pattern of variation among 13 Black pine (Pinus nigra Arn.) and 14 Scots pine (Pinus sylvestris L.) European populations was conducted by using allozyme markers. The evaluation of genetic diversity parameters, i.e. mean number of alleles per locus (A/L), effective number of alleles (Ae), percentage of polymorphic loci (P), expected heterozygosity per population (He), for the two species indicated that both Black and Scots pine are characterized by high levels of variation. The genetic differentiation coefficient (Gst) and genetic distances were higher for the Black pine populations. For Scots pine populations, excluding that of the Iberian Peninsula which seems to retain a Tertiary gene pool, genetic distances were low, even between populations of great geographical distance (Sweden-Balkan countries). The principal coordinate analysis and cluster analysis also confirmed the different genetic variation pattern of the two species. The results can be interpreted by the different evolutionary course of the two pine species, especially during the post-glacial period.