12 nuclear microsatellite loci scores for 543 adult trees of Tilia cordata in Lithuainia

Genetic signature of the natural genepool of Tilia cordata Mill. in
Lithuania: compound evolutionary and anthropogenic effects Tilia cordata
Mill. is a valuable tree species enriching the ecological values of the
coniferous dominated boreal forests in Europe. Following the historical
decline, spreading of Tilia sp. is challenged by the elevated inbreeding
and habitat fragmentation. We studied the geographical distribution of
genetic diversity of Tilia cordata populations in Lithuania. We used 14
genomic microsatellite markers to genotype 543 individuals from 23 wild
growing populations. We found that Tilia cordata retained high levels of
genetic diversity (population Fis = 0 to 0.15, Ho = 0.53 to 0.69, He =
0.56 to 0.75). AMOVA, Bayesian clustering and Monmonier’s barrier
detection indicate weak but significant differentiation among the
populations (Fst = 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
Tilia cordata on rich and most soils of midland lowland, and (c) the most
differentiated populations on poor soils of the coolest north-eastern
highland possessing the highest rare allele frequency but elevated
inbreeding and bottleneck effects. Weak genetic differentiation among the
Tilia cordata 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 geneflow
mediators in Tilia cordata was raised based on results of this study.