A molecular study of the population and family genetic structure of the African elephant (Loxodonta africana Blumenbach 1797)

Abstract

Abstract by author:

An assessment of population structure of elephant populations in Uganda using variation at microsatellite loci and mitochondrial DNA (mtDNA) control region sequences revealed significant genetic differentiation between the populations Queen Elizabeth National Park, Murchison Falls National Park and Kidepo Valley National Park. A low level of mtDNA variation was observed in the Queen Elizabeth population compared to Murchison Falls and Kidepo Valley populations. We interpreted this observation as an indication of a historically small population size in Queen Elizabeth national park and relatively larger founder population sizes for the Murchison Falls and Kidepo Valley populations. Comparison of nuclear and mtDNA analyses revealed incongruent genetic scenarios which suggested a significant role of male-biased gene flow in shaping the population structure of the Uganda elephant populations

Analysis of elephant population structure on a continental scale revealed significant genetic differentiation between populations based on both mitochondrial and nuclear DNA markers. We have also observed significant regional differentiation between elephant populations in eastern, western and southern Africa. However, very little genetic differentiation was found between the southern African populations; a situation that can be attributed to the relatively large elephant population sizes still present in this region coupled with relatively more efficient protection of elephant herds against poaching. In Botswana, Zimbabwe and Namibia the main management concern has shifted in focus; the wildlife management authorities are preoccupied with curbing further increase in the sizes of their elephant populations in order to prevent further habitat degradation. This is why, following a series of debates on the status of elephants in these three countries, it was finally agreed during the COP-10 meeting held in Harare, Zimbabwe, in June 1997 that their elephant populations be downlisted by the Convention for International Trade of Endangered Species of wild flora and fauna (CITES) from appendix I to appendix II. This was to facilitate restricted trade in the ivory coming from the elephant culling operations in these countries

Unlike in most population studies carried out using control region sequence variation, we have observed low levels of variation in the elephant control region relative to the other large mammals studied so far and also relative to the cytochrome b gene in the same species. Our data shows the control region to be evolving at the same rate as the cytochrome b gene. We have not been able to conclusively establish the underlying causes of such a phenomenon during the course of this study. Nevertheless this aspect will be a subject of our further investigation in future studies