Range-wide mtDNA phylogeography yields insights into the origins of Asian elephants

Vidya, TNC and Sukumar, Raman and Melnick, Don J (2009) Range-wide mtDNA phylogeography yields insights into the origins of Asian elephants. In: Proceedings Of The Royal Society B-Biological Sciences, 276 (1658). pp. 893-902.

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Abstract

Recent phylogeographic studies of the endangered Asian elephant (Elephas maximus) reveal two highly divergent mitochondrial DNA (mtDNA) lineages, an elucidation of which is central to understanding the species's evolution. Previous explanations for the divergent clades include introgression of mtDNA haplotypes between ancestral species, allopatric divergence of the clades between Sri Lanka or the Sunda region and the mainland, historical trade of elephants, and retention of divergent lineages due to large population sizes. However, these studies lacked data from India and Myanmar, which host approximately 70 per cent of all extant Asian elephants. In this paper, we analyse mtDNA sequence data from 534 Asian elephants across the species's range to explain the current distribution of the two divergent clades. Based on phylogenetic reconstructions, estimates of times of origin of clades, probable ancestral areas of origin inferred from dispersal-vicariance analyses and the available fossil record, we believe both clades originated from Elephas hysudricus. This probably occurred allopatrically in different glacial refugia, the a clade in the Myanmar region and the beta clade possibly in southern India-Sri Lanka, 1.6-2.1 Myr ago. Results from nested clade and dispersal-vicariance analyses indicate a subsequent isolation and independent diversification of the b clade in both Sri Lanka and the Sunda region, followed by northward expansion of the clade. We also find more recent population expansions in both clades based on mismatch distributions. We therefore suggest a contraction-expansion scenario during severe climatic oscillations of the Quaternary, with range expansions from different refugia during warmer interglacials leading to the varying geographical overlaps of the two mtDNA clades. We also demonstrate that trade in Asian elephants has not substantially altered the species's mtDNA population genetic structure.

Item Type:	Journal Article
Publication:	Proceedings Of The Royal Society B-Biological Sciences
Publisher:	The Royal Society
Additional Information:	Copyright of this article belongs to The Royal Society.
Keywords:	phylogeography;divergent mitochondrial clades;Pleistocene refugia;elephant trade;Elephas fossils
Department/Centre:	Division of Biological Sciences > Centre for Ecological Sciences
Date Deposited:	05 Nov 2009 08:42
Last Modified:	19 Sep 2010 05:27
URI:	http://eprints.iisc.ac.in/id/eprint/19166

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