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University of Glasgow (2020)

Development of genetic tools for managing populations of the Southern white rhinoceros (Ceratotherium simum simum).

Purisotayo, Tarid

Titre : Development of genetic tools for managing populations of the Southern white rhinoceros (Ceratotherium simum simum).

Auteur : Purisotayo, Tarid

Université de soutenance : University of Glasgow

Grade : Doctor of Philosophy (PhD) 2020

Résumé partiel
The southern white rhinoceros (SWR) is one of five extant species of rhinoceros. The species experienced historical bottleneck due to unrestricted hunting and was on the brink of extinction during the end of nineteenth century, with only one population remaining in South Africa. This population was intensively protected and as it subsequently increased, it became the source of SWR for all of Southern Africa. With advances in immobilisation and translocation techniques, a surplus SWRs were relocated to the former range states of the species. Therefore, most or all modern populations of SWRs originated from the single founder population. As in other former range states, Botswana re-established SWR populations, but poaching remained an imminent threat to the national herd and the species was almost wiped out for a second time. In response to this threat, the Department of Wildlife and National Parks of Botswana (DWNP) began to capture free ranging animals and relocate them into enclosed reserves where they could be protected intensively by anti-poaching teams. Subsequently the population size of the national herd has been increasing due to successful breeding together with the continued introduction of SWRs from South Africa. Although this conservation strategy has been successful, it has generated many fragmented populations, which required regular exchanges of animals to prevent inbreeding. However, selection of animals for translocation has been made based on observational data about the relationships among animals and genetic information has rarely been used. The efficient identification of candidates for translocation, requires an accurate and complete pedigree to determine the individuals with high risk of producing inbred progeny. In this thesis, three populations of SWRs in Botswana (Botswana1, Botswana2, and Botswana3) were used as models to develop genetic tools that would facilitate metapopulation management.

The purpose of Chapter 2 was to integrate previously characterised microsatellites (MS) genotypes with an incomplete, field-observed pedigree to make inferences about mean kinship and basic demographic data that could be used to inform translocation programmes for SWR. Level of heterozygosity and genetic diversity of the population were not as low as initially expected based on the severe bottleneck, but the population showed a very low mean number of alleles per locus. Using several different strategies for exclusion of unlikely parents, parental pairs of 29 out of 45 offspring could be assigned confidently. The combined pedigree was constructed from the assignable parent-offspring relationships and subsequently used to estimate kinship coefficients. Based on population mean kinship (MK), eight bulls with high individual MK could be identified as the best candidates for translocation. The pedigree was further used to estimate population demographic parameters ; importantly, the reproductive dominance of the bulls was not as skewed as expected after the original dominant bull was removed, suggesting that closed populations can maintain multiple, simultaneously breeding males.

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