Primates in Northeast showing a drop in population sizes, finds CSIR-CCMB-led study

Study by LaCONES scientists reveals decline in primate populations in Northeast India due to climate change, urging urgent conservation efforts.

Primates in Northeast India noticeably are showing a stark drop in population sizes though each species has followed a variety of evolutionary trajectories due to climate variations to become the confluence of various species present today.

A new study by scientists of LaCONES — Laboratory for the Conservation of Endangered Species at the CSIR — Centre for Cellular and Molecular Biology (CCMB) has also shown that the reduction in population may not be only due to factors related to anthropogenic or human activity.

The research was conducted over nine different primates, including Macaca arctoides, M. leonine, M. assamensis, M. thibetana, Trachypithecus pileatus, T. phayrei, T. geei, Hoolock hoolock and Nycticebus bengalensis between 2019-2023.

Blood samples of these species were collected from captive animals in different zoos and rescue centres and whole genome was sequenced at CCMB. The population history was studied during two climatic periods — Pliocene (5.33 million-2.5 million years) and Pleistocene (2.58 million years ago to 11,700 years ago).

It showed that while the effective population size of all the primate species have decreased with time, the geographical distribution models of different species showed different variations. Some species have contracted their distributions and other have been found expanding it towards Himalayan foothills and elsewhere. The population sizes of all these species are identical till the mid-Pleistocene boundary or about 787,000 years ago and then the divergence happened of varied geographical distribution and reduction of population.

“This analysis gives an idea about how each species is affected differently by climate change, and why it should be emphasized framing species-wise conservation models for future climate change. We need more geographical data and availability of more samples from each species,” explained chief scientist G. Umapathy, lead author of this publication.

He called for an extensive future research programme to understand primates and other taxa, towards better conservation of bio-diversity and species-wise conservation models for future climate change in the region. The scientist pointed out that of the 14 primate species found in the region, except Rhesus macaque, all are assessed to be Near Threatened or at a higher risk by IUCN RedList.