Gene‑ecological zonation and population genetic structure of Tectona grandis L.f. in India revealed by genome‑wide SSR markers

摘要

Population genomics determines the evolutionary potential of a species by decoding the genetic structure and diversity of populations from diverse eco-geographical gradients. Tectona grandis L.f., being a tropical timber tree species distributed in diverse environmental and geographical conditions, is more responsive to local adaptation. This study investigates the extent of genetic variation of teak natural populations in India using genome-wide SSR markers, thereby identifying the role of isolation by distance and environment in shaping genetic structure. Bottleneck effect along with genetic drift and local adaptation shaped the genetic structure of populations which formed three gene-ecological zones, namely, Kerala, Tamil Nadu-Karnataka, and Karnataka, Central India (Gujarat and Madhya Pradesh). Historical gene flow was greater as compared to recent gene flow indicating habitat loss and fragmentation in framing the present population structure of natural teak populations. Genetic diversity of teak populations in India was guided by joint influence of environmental variables and geographical factors. Decline in the genetic diversity of populations in west-east pattern was perceived. Further, more than one area in the Western Ghats acted as refugia during glacial period. The populations/genotypes with higher private or adaptive alleles could be targeted for sustainable management, conservation, and genetic improvement of teak genetic resources in the country. Niche modelling identified central Indian populations to be more vulnerable to climate change and probable shift in the distribution pattern of the species in the ensuing years.