Population genetics and systematics of Asian elephant (Elephas maximus): A study based on sequence variation at the Cyt b gene of PCR-amplified mitochondrial DNA from hair bulbs

To investigate genetic variability and differentiation in Asian elephant (Elephas maximus) a total of 53 individuals from Sri Lanka, southern India, northeastern India, northern and southern Myanmar (Burma), northern and eastern Thailand, and Vietnam were screened for sequence variation at the mitochondrial cytochrome b gene. An about 480 bp part of the gene was PCR amplified from hair bulbs, directly cycle-sequenced, and 335 bp were analysed on a direct blot sequencing device. Eight haplotypes, differing from one another by one to six third position transitions at a total of seven polymorphic sites, were found. They differed from published sequences of African elephant (Loxodonta africana) by at least 18, and from those of the Siberian woolly mammoth (Mammuthus primigenius) by at least eight nucleotide substitutions. Haplotypes separated out by nucleotide divergence into two major groups, which showed differences in their geographic distribution. However, there was no indication of a major separation between elephants from Sri Lanka and the Asian mainland, previously assumed to represent two different subspecies. Populations studied showed remarkable differences as to estimates of haplotype and nucleotide diversity Phylogeographic patterns of haplotypes suggest that Asian elephants have formed a coherent population after their Pliocene invasion of southern and southeastern Asia. Taking into account records on population histories, the present local differentiation can be explained by varying human impact on population structure and size.