Browsing by Author "Le Roex, Nikki"
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- ItemOpen AccessGenetic admixture of Kruger National Park black rhino (Diceros bicornis minor): conservation implications(2020) Stanbridge, Deborah; O'Riain, Justin; Le Roex, NikkiBlack rhinoceroses (Diceros bicornis) have been extirpated from most of their historic range with the remaining individuals (ca. 5200) living in geographically isolated populations. Management priorities include creating new populations whilst maintaining genetic diversity and promoting gene flow between existing isolated populations. Such objectives are however currently hindered by a lack of comparative/reference data on levels of diversity, relatedness and inbreeding in a large, free-ranging black rhinoceros population. Here I attempt to address this gap in our knowledge by investigating the genetic diversity of the black rhinoceros Diceros bicornis minor within Kruger National Park (the largest free-ranging population of this subspecies) using nuclear and mitochondrial DNA. I compared the diversity of this founded population with the two source populations (KwaZulu-Natal, South Africa and Zimbabwe) using published studies, and evaluate the relative contribution of source lineages relative to the proportion of original founders. Analysis of the mtDNA control region revealed four haplotypes, with moderate haplotype and nucleotide diversity (h=0.48 (± 0.05 SD); π= 0.29%). Data from 13 microsatellite loci revealed moderate to high levels of genetic variation (number of alleles = 4.92 ± 0.90, effective number of alleles = 2.26 ± 0.25, observed heterozygosity = 0.50 ± 0.04, expected heterozygosity = 0.51 ± 0.04), low mean pairwise relatedness (r = -0.03), a low inbreeding coefficient (Fis = 0.04) and no evidence of genetic structuring. Diversity levels within the Kruger black rhinoceros population were high compared to levels reported in black rhinoceroses originating in KwaZulu-Natal and similar to those reported in individuals originating in Zimbabwe. Results show that 40-60% of the Zimbabwean lineages are represented in the Kruger population which is a noticeable increase in the relative contribution of the Zimbabwe founder population. The data provided by this study can be used to guide management and conservation decisions regarding maximising genetic variability across the subspecies. Furthermore, given the encouraging levels of genetic diversity observed, the Kruger black rhinoceros population would be an ideal source population for supplementation of genetically depauperate populations or creating new populations. Finally, these findings demonstrate a positive outcome in mixing the KwaZulu-Natal and Zimbabwe gene pools, with evidence that the founder Kruger black rhinoceros population has been genetically rescued from the low diversity seen in the KwaZulu-Natal black rhinoceroses in South Africa.
- ItemOpen AccessPhylogeographic analysis reveals strong geographical structuring in the klipspringer, Oreotragus oreotragus(2008) Le Roex, Nikki; O'Ryan, ColleenThe klipspringer, Oreotragus oreotragus, occurs from the Western Cape of South Africa through to north-east Africa. Anthropological factors such as hunting have eradicated the klipspringer in parts of its former range and efforts have begun to reintroduce klipspringer back into these areas. This has highlighted the need for the proper understanding of the genetic variation, phylogeographic and population structure of the species, as well as the genetic validity of the 11 subspecies designations. Mitochondrial control region and cytochrome b sequence data were used to investigate these topics using blood, faecal and museum specimens. Cytochrome b and control region fragments were amplified in 83 and 60 samples respectively, out of a total sample set of 89 individuals. The generation of authentic mitochondrial DNA control region fragments proved difficult, with both Numt and PCR recombinant sequences identified after amplification. High levels of genetic variation were observed in the klipspringer, with cytochrome b and control region haplotype diversities of 0.78 and 0.98 respectively. Phylogenetic and network analyses showed the distinct geographical clustering of individuals into two major groups, south/south-western (S/SW) and east/north-eastern (E/NE), with the S/SW further split into two divergent groups. This suggests that the two S/SW groups were separated and isolated as a result of shifting climatic conditions in the late Pl iocene/early Pleistocene, after which secondary contact occurred and klipspringer moved upwards from southern Africa to colonise the east. The results from this study have conservation implications with respect to translocation policies, suggesting that translocations should only occur within the geographic groups identified in order to avoid outbreeding depression.