Population genetic structure of a timberline oak (Quercus semecarpifolia Sm.) of western Himalayas and conservation implications.

Forests are considered as one of the most complex terrestrial ecosystems due to their high level of biodiversity, including genetic diversity. Understanding the genetic diversity of keystone species at a population level is vital to forest managers and policymakers for the conservation and sustainable utilization of forest genetic resources. Quercus semecarpifolia, commonly known as brown oak, is a keystone species of climax community thriving in the alpine zone of the Himalayas, which is presently experiencing population decline and range shift under the changing climate. In the present study, a landscape genetic approach was employed for deciphering the population genetic structure of Q. semecarpifolia in the western Himalayas using nuclear simple sequence repeat (SSR) markers. By analysing 718 individuals of 24 populations at 10 SSR loci, a high gene diversity (expected heterozygosity, He = 0.72; Allelic richness, Ar = 8.37) was recorded with a moderate genetic differentiation (F_ST = 0.16; P < 0.001). Genetic clustering and STRUCTURE analysis have displayed two major gene pools which appear to be primarily differentiated by the landscape and ecological constraints rather than the linear geographical distances. The hierarchical AMOVA analysis further supports the regional genetic divergence with a substantial proportion of genetic variation detected among the regions. Diversity maps generated by spatial interpolation elucidated the distribution pattern of genetic diversity and structure across the range, and aid in the demarcation of the diversity hotspots for conservation implications. To the best of our knowledge, this is the first comprehensive genetic study carried out in any Himalayan oaks, and the information generated herein is novel and of paramount importance in guiding conservation decisions. [ABSTRACT FROM AUTHOR]