Sequence variation at two mitochondrial genes in the Asian elephant (Elephas maximus) population of Sri Lanka

The elephant population in Sri Lanka, estimated to be 4000, is currently fragmented and restricted mainly to a few elephant reserves. As a prerequisite for future conservation and management measures, this study aims at assessing the genetic population structure of the elephants of Sri Lanka with regard to geographic population structure and levels of genetic variability. DNA sequence variability was analyzed in two mitochondria) genes, NADH dehydrogenase subunit 5 (ND 5) and Cytochrome b (Cyt b). A total of 67 elephant samples was analyzed for both genes, yielding seven distinct ND 5-Cyt b mtDNA haplotypes. Phylogenetic analysis of these haplotypes revealed the presence of one haplotype (T3M6) well separated from the rest with a mean sequence divergence of 1.61%. The study does not confirm the subspecies status of the elephant population of Sri Lanka. Within Sri Lanka, the sequence divergence among regions was small and did not suggest a Longterm divergence into regional subpopulations. Nevertheless, significant geographic substructure was observed with regard to haplotype frequencies, indicating limited genetic exchange among regions at present. Genetic variability was high in all analyzed regions. The inferred limitation of present long-distance genetic exchange could reflect an effect of the fragmentation of the former continuous distribution.