Differences in spatial genetic population structure between African and Asian elephant (Loxodonta africana, Elephas maximus) as revealed by sequence analysis of the mitochondrial Cyt b gene

To assess spatial genetic population structure of both extant elephant spec ies, we investigated sequence variation in 369bp of the mitochondrial Cyt b gene in 23 specimens of African elephant Loxodonta africana (Blumenbach, 1 797) from three regions in the Southern part of Africa. In an integrated an alysis, these results were compared to data of a previous study, where the same gene region had been analysed in 53 Asian elephants Elephas maximus (L innaeus, 1758) from 5 different regions on Sri Lanka and Asian mainland. In Loxodonta, 14 polymorphic sites defined 6 different mitochondrial haplotyp es with a mean sequence divergence of 2.085%. In Elephas, 6 polymorphic sit es defined 8 different haplotypes with a mean sequence divergence of 0.942% . Compared to other mammals, genetic variation is high in Loxodonta and mod erate in Elephas. The difference in genetic variation among the species cou ld be explained either by a Pliocene bottleneck in Elephas or by different long term effective population sizes. In Elephas, a star like phylogeny of haplotypes was found, indicative of a population expansion after a bottlene ck. In Loxodonta, very divergent mtDNA lineages coexisted, suggesting the a bsence of any bottleneck in population history. Within regional subpopulati ons, both species showed similar mean haplotype diversities, while mean nuc leotide diversity within regions was higher in Loxodonta than in Elephas. T his suggest larger long-term effective population sizes in Loxodonta, while short-term effective population sizes are presumably similar in both speci es. Spatial genetic population structure in Loxodonta is mainly determined by isolation-by-distance, while in Elephas it is impacted by human transloc ation. Human translocation might have prevented isolated small Elephas popu lations from severe genetic depletion.