Genetic relationships between Polish and reference populations of Scots pine (Pinus sylvestris L.) in Europe based on nucleotide polymorphism study at nuclear loci

Adaptation to local environmental gradients is one of main characteristics of living organisms. Scots pine (Finns sylvestris L.) is the most widely distributed conifer in the world and main forest forming component in Europe. Based on genetic, morphological and growth performance traits, several local ecotypes of the species were distinguished across the species distribution range. The existence of local ecotypes differentiated at many adaptive and phenotypic traits provides unique opportunity for addressing the questions about the genetic basis of local adaptation across the species distribution range. However, information about the underlying population structure between ecotypes is needed for efficient studies of adaptive variation at molecular level. The presented study focused on the genetic variation analysis between nineteen populations of Scots pine from across geographical locations in Poland and eleven reference samples from Northern, Western and Southern Europe. The pattern of nucleotide polymorphisms at 673 polymorphic nucleotide sites found across twenty nine nuclear loci was studied to determine genetic relationship and population structure of different geographical locations. Genetic relationships between populations were conducted based on Baysian assignment and conventional frequency based statistics at the within and between population level. The results indicate very uniform genetic background of Polish populations of the species that despite high phenotypic and ecological differentiation most likely share the same recolonization history. High genetic similarity was found between Polish and North European range of the species. In contrast, differentiation was found in relation to the reference populations from Scotland and Spain that in previous studies were shown to deviate from simple recolonization model after last glaciations and had unique mtDNA mitotypes not observed in continental continuous range of the species, respectively. Considering high differentiation at quantitative traits between northern and central part of the species range in Europe but very homogenous genetic background found in the presented study, it seems that this part of Scots pine distribution is particularly suitable for association genetic studies to find genomic regions that are involved in species adaptive and phenotypic variation.