Evolutionary History and Population Genetic Structure of Asian Elephants in India

The Asian elephant (Elephas maximus), which has shared a long and rich cultural relationship with humans in India, is endangered in the country today, largely because of habitat loss. There are an estimated 41,400-52,300 Asian elephants worldwide, of which over half range in India. I describe studies that examined the evolutionary history of the Asian elephant, uncovering a surprising coexistence of divergent clades of mitochondrial DNA (mtDNA) within the species, often within populations. Several hypotheses were proposed to explain this coexistence of divergent clades, but it required extensive sampling of elephants from India (because of its large populations of elephants), along with samples from other countries, to gain an understanding of Asian elephant phylogeography, which was found to be largely shaped by Pleistocene climatic oscillations. I also describe studies of the genetic variability of the Indian populations based on mtDNA and nuclear microsatellite DNA and discuss reasons for the patterns seen. Examination of population genetic structure within India, and the geographic barriers that gave rise to such structuring are also described. I end with possibilities for future research, such as addressing the possibility of subspecies within the Asian elephant, understanding the low levels of genetic diversity in southern India, and explaining patterns of population genetic differentiation and breaks in gene flow in elephants and other animals in southern and northeastern India.