Genetic diversity of the eastern black rhinoceros (Diceros bicornis michaeli) in Tanzania; implications for future conservation

Abstract

In the past decade, there has been a drastic decline in the number of Eastern Black rhinoceros (Diceros bicornis michaeli), due to poaching, leaving few individuals in small, isolated populations that are vulnerable to extinction. However, the genetic consequences of the demographic decline on the remaining populations have not been investigated. Using the mitochondrial control region, this study investigated how current levels of genetic diversity relate to historical patterns, quantified genetic differentiation between extant populations, and the impacts of previous translocations on genetic diversity across populations. A total of 74 eastern black rhinoceroses were sampled from five extant populations in Tanzania and one neighboring cross-border population in the Maasai Mara in Kenya. Six maternal haplotypes were identified, with an overall haplotype diversity of h = 0.7 but low overall nucleotide diversity within populations (π = 0.017) compared to historical populations from Tanzania (π = 0.021). There was extensive variation in haplotype distribution between populations, some geographically close populations didn’t share haplotypes, suggesting limited maternal dispersal. The haplotypes were distributed among three east African haplogroups (Shari-Victoria(CV), Central-East(CE), and East-Africa(EA) as described in previous studies, suggesting that multiple lineages have been preserved despite the loss of haplotypes. One of the haplotypes was highly divergent and matched sequences previously classified as a subspecies that has not been recognized in recent years (Diceros bicornis ladoensis). We recommend that current levels of diversity be maintained by allowing natural movements of rhinoceroses between the populations, with the possibility of introducing additional variations by translocation of individuals between sites.