Genetic signature of the natural gene pool of Mill. in Lithuania: Compound evolutionary and anthropogenic effects.

Mill. is a valuable tree species enriching the ecological values of the coniferous-dominated boreal forests in Europe. Following the historical decline, spreading of sp. is challenged by the elevated inbreeding and habitat fragmentation. We studied the geographical distribution of genetic diversity of populations in Lithuania. We used 14 genomic microsatellite markers to genotype 543 individuals from 23 wild-growing populations. We found that retained high levels of genetic diversity (population  = 0-0.15,  = 0.53-0.69,  = 0.56-0.75). AMOVA, Bayesian clustering, and Monmonier's barrier detection indicate weak but significant differentiation among the populations (  = 0.037***) into geographically interpretable clusters of (a) western Lithuania with high genetic heterogeneity but low genetic diversity, bottleneck effects, (b) relatively higher genetic diversity of on rich and most soils of midland lowland, and (c) the most differentiated populations on poor soils of the coolest northeastern highland possessing the highest rare allele frequency but elevated inbreeding and bottleneck effects. Weak genetic differentiation among the populations in Lithuania implies common ancestry, absence of strong adaptive gradients, and effective genetic exchange possible mediated via the riparian networks. A hypothesis on riparian networks as gene flow mediators in was raised based on results of this study.