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Le Roex, N.; Paxton, M.; Adendorff, J.; Ferreira, S.; O'Riain, M.J., 2018. Starting small: long-term consequences in a managed arge-mammal population. Journal of Zoology (London) 306 (2): 95-100

Location: Africa - Southern Africa - South Africa
Subject: Conservation
Species: Black Rhino

Original text on this topic:
Small populations are vulnerable to founder effects, stochastic demographic events and inbreeding depression. These factors raise the extinction probability of small populations, and thus effective management plans for endangered species have become essential. The black rhinoceros (Diceros bicornis) survived a historic global population crash and is currently facing renewed threat through poaching, population fragmentation and isolation. South Africa is home to approximately 36% of the world's remaining black rhinos; however, this population is fragmented across parks and reserves, and many of these small populations remain geographically and genetically isolated. The historic population crash, subsequent fragmentation and relentless poaching pressure together threaten the viability of the black rhino population within South Africa. This study employed a practical, non‐invasive sampling protocol and genetic analyses to assess the growth and performance of a small founder population in a fenced reserve. We used these data and recorded life‐history data to compare the population growth and vital rates between the first and second 10‐year periods since founding. We report a decrease in population growth rate and male survival in the second 10‐year period (0.06; 0.89) compared to the first (0.09; 0.97). Genetic diversity (HEXP = 0.405) was low when compared to larger black rhino populations, and average pairwise relatedness was high (0.193). These results suggest that negative genetic consequences and the beginning of density‐dependant growth regulation may be present in this population. This highlights the importance of establishing an evaluation framework for the assessment of small populations of long‐lived mammals in order to inform metapopulation management.

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