Geographic distribution of quantitative traits variation and genetic variability in natural populations of Pinus mugo in Central Europe

Divergence in genetic as well as phenotypic structures can be expected in species with disjunctive geographic ranges and restricted gene flow among isolated populations. Dwarf mountain pine has such a disjunctive geographic range in the mountains of Central Europe. We hypothesised that populations of Pinus mugo from the Giant Mts. differ from Alpine and Carpathian populations to a greater extent than differentiation within these regions; furthermore, these differences would be detectable at both the genetic and phenotypic levels. To verify this hypothesis, the diversity and differentiation within and among eleven populations from the Giant Mts., Carpathians and Alps were analysed using 19 isozyme isozyme loci, 17 needle and 15 cone morphological characters. Moreover, the data on 10 chloroplast microsatellites used in the previous study, were reanalysed. The differences between the three regions were greater than among populations within them. The microsatellites and isozymes clearly differentiated between regions, while in the multivariate analyses of cone and needle characters the Alpine and Carpathian populations were intermingled but distinct from those sampled in the Giant Mts. The significant genetic structuring among regions may result from an ancient fragmentation and long lasting geographic isolation between the Giant Mts., Alps and Tatras. The populations from the Giant Mts., the northernmost within the geographic range of P. mugo, presented lower level of genetic variation then those from the Alps and Carpathians. The pattern of genetic structure observed in dwarf mountain pine may be characteristic of wind-pollinated trees with a disjunctive geographic distribution