Historical demography and species distribution models shed light on past speciation in primates of northeast India

Objectives To ascertain the effect of historical demography and past climate change as the drivers of diversity in northeast India. Materials and methods We took the variant called whole genome files of nine species present in the northeast India from Primate genome sequencing consortium work and assessed each species historic effective population size by using Multiple Sequentially Markovian Coalescent (MSMC) tool. We also constructed species distribution models on past (Pliocene and Pleistocene) and present climate with Maxent, by utilizing publicly available distribution data for each species. Results We got the effective population sizes for 10 million years ago at most, though we considered the data only till 3.3 million years. All species showed rise and decline at various time periods. The species distribution models showed disparate distribution at all three time points with a genera-wise pattern emerging. Discussion We found that the evolutionary trajectories of all the four genera into consideration, Macaca, Trachypithecus, Hoolock and Nycticebus are different from each other. Species in Macaca looks to be evolved in northeast as well as come from southeast Asia. Some species of Trachypithecus seems to radiated in the northeast India. Similarly, Hoolock has evolved in the region and Nycticebus is predicted have arrived from Indochina in the region. Hence, this study provides unique insights to the evolutionary dynamics for primate species in the northeast India.