A dramatic decline in genetic diversity of black rhinos

Scientific Reports, DOI:10.1038/srep41417

Black rhinos (Diceros bicornis) are once again on the brink of extinction. During the 20th century, the black rhino, which has previously lived in most of the sub-Saharan Africa, has declined by more than twenty-fold until the mid-1990s, when intensive protection led to a population recovery to just over 5,000 individuals by 2014. In recent years, however the rhinos are severely threatened once more due to a steady increase of the price of a horn that is now worth more than 65,000 USD per kilogram on the black market. The poachers are therefore very active and kill over a thousand rhinos each year. If this trend continues, the population of the black rhinoceros will collapse and in less than twenty years, the species will go extinct.

Despite the popularity of rhinos, we know relatively little about their evolutionary history and genetic diversity of their populations. This knowledge is crucial for the efforts to save these animals. Jan Robovský at the Department of Zoology, Faculty of Science, became a member of a large international team of researchers that studied the genetics of both historical and modern black rhino populations – the largest sample of these animals that scientists have ever worked with.

The team have processed data on mitochondrial and nuclear DNA, and have come to the conclusion that the species have already lost about 69 percent of its mitochondrial genetic diversity, including its very oldest evolutionary lineages. Many genetically distinct populations of the black rhino that were living in Nigeria, Cameroon, Chad, Eritrea, Ethiopia, Somalia, Mozambique, Malawi, and Angola have already gone extinct. Based on their results, the researchers have identified key black rhino populations that conservationist need to concentrate their efforts on. At the same time, they propose to thoroughly reassess current priorities and practices of protecting this unique animal.

Moodley, Y., Russo, I. R. M., Dalton, D. L., Kotzé, A., Muya, S., Haubensak, P., Bálint, B., Munimanda, G. K., Deimel, C., Setzer, A., Dicks, K., Herzig-Straschil, B., Kalthoff, D. C., Siegismund, H. R., Robovský, J., O’Donoghue, P., & Dicks, K. (2017). Extinctions, genetic erosion and conservation options for the black rhinoceros (Diceros bicornis). Scientific Reports7, 41417.