Genetic variation and population structure in remnant populations of black rhinoceros, Diceros bicornis, in Africa

Abstract

Black rhinoceros (Diceros bicornis) are one of the most endangered mammal species in Africa, with a population decline of more than 96% by the end of the last century. Habitat destruction and encroachment has resulted in fragmentation of the remaining populations. To assist in conservation management, baseline information is provided here on relative genetic diversity and population differentiation among the four remaining recognized subspecies. Using microsatellite data from nine loci and 121 black rhinoceros individuals, and comparing the results with those of other African species affected in similar ways, Diceros bicornis michaeli retained the most genetic diversity (heterozygosity 0.675) compared with Diceros bicornis minor (0.459) and Diceros bicornis bicornis (0.505), suggesting that the duration of the known bottlenecks in these populations has only had a limited impact on diversity. Comparable and moderate degrees of population differentiation were found between D. b. minor, D. b. bicornis and D. b. michaeli. Results from the single sample available of the most endangered subspecies, Diceros bicornis longipes, showed the least diversity of all individuals examined. This information should assist conservation management decisions, especially those affecting population viability assessments and selection of individuals for translocations, and will also facilitate subspecies identification for ex situ individuals of uncertain origin.

Mitochondrial DNA Phylogenetics of Black Rhinoceros in Kenya in relation to Southern Africa Population

“…Some authors suggest that each subspecies population may have behavioral adaptations to their local environments [3,12]. The two subspecies are not genetically reproductively separated and there have been no rigorous studies on migration and reproductive gene flow between these populations [12]. In this study, phylogenetic analysis of these populations using mtDNA D-loop region (Figure 1) shows that the two populations fall into two different clades that have further separated into monophyla clusters over time.…”

“…The Eastern Africa black rhinoceros (D. b. michaeli) is historically separated from the southern population (D. b. minor) although there is no real geographical barrier to limit movement between the two regions. Some authors suggest that each subspecies population may have behavioral adaptations to their local environments [3,12]. The two subspecies are not genetically reproductively separated and there have been no rigorous studies on migration and reproductive gene flow between these populations [12].…”

“…Although there are apparently no marked geographic or reproductive barriers between the subspecies, they occupy different ecological 2 International Journal of Biodiversity zones. There have not been any rigorous studies on migration and reproductive gene flow between the subspecies although some authors suggest that each subspecies may have distinct genetic or behavioral adaptations to their local environments [3,12].…”

“…Mitochondrial DNA (mtDNA) phylogeny sheds light on founder female populations and can be applied in determining black rhinoceros population relationships across the ecological and geographic zones [15,16]. The measure of variability within and between groups is an essential step in determining robust numbers of individuals in a sanctuary that preserves genetic diversity of these populations [12,17]. In this study we analyzed mtDNA genetic relationships between Kenyan black rhinoceros population and the Southern Africa counterpart to assess gene flow between the populations.…”

Characterization of microsatellite loci in the black rhinoceros (Diceros bicornis) and white rhinoceros (Ceratotherium simum): their use for cross-species amplification and differentiation between the two species

“…The black rhinoceros (Diceros bicornis) is one of the most endangered species in Africa, with population estimates ranging from 3,600 to 2,400 individuals remaining (International Rhino Foundation 2006), and the white rhinoceros (Ceratotherium simum), is estimated to have a remaining population size around 11,000 individuals (International Rhino Foundation 2006). The establishment of a genetic diversity database within these species will help conservation efforts with regards to translocation of individuals, population viability assessments that are in the best interest of the rhinoceroses (Harley et al 2005;Florescu et al 2003) and will help decisions in the future with regards to increasing or decreasing genetic diversity of the rhinoceroses. Overall this will help conservation managers make critical decisions that will ultimately lessen the species' risk for extinction.…”