Mitochondrial DNA sequence data of the Cape fur seal (Arctocephalus pusillus pusillus) suggest that population numbers may be affected by climatic shifts
The Cape fur seal, Arctocephalus pusillus pusillus is distributed along the southern African coastline from northern Namibia to the south-east coast of South Africa. The species has been impacted by sealing operations since the 1600s, and historical records suggest that the taxon experienced a bottleneck prior to the 20th century. Mitochondrial DNA control region sequences were generated for 106 individuals belonging to six breeding colonies. Haplotype diversity was found to be high (0.975±0.014) whereas levels of nucleotide diversity were much lower compared to other seal species (0.011±0.006). An analysis of molecular variance indicated that the largest percentage of haplotype diversity is distributed within colonies rather than among them. This could be attributed to either extensive gene flow among colonies, a lack of substantial female site philopatry, or incomplete lineage sorting of haplotypes. Mismatch distribution and Fu’s FS test indicated that the population has experienced a historical population expansion probably between c. 37,000–18,000 YBP and this date coincides very well with the height of the last glacial maximum when food resources were abundant in the South Atlantic. These results also suggest that the recent sealing-induced bottleneck did not have a profound influence on the haplotype diversity and a historical bottleneck prior to a demographic expansion may have been severe enough to reduce nucleotide diversity substantially.
KeywordsMismatch Distribution Breeding Coloni Female Philopatry Black Rock Seal Species
Stellenbosch University and South African National Research Foundation (GUN 2053617) for funding the molecular work. MCM and the BENEFIT Programme provided funding for the collection of samples. The following persons assist with the collection of the material: S Swanson, N Mukapuli, D Kotze, E Olsen, M Mauritzen, G Sikute, K Tangeni and D Reynolds.
- Kerley GIH (1983) Record for the Cape fur seal Arctocephalus pusillus pusillus from subantarctic Marion Island. S A J Zool 18:139–140Google Scholar
- King JE (1983) Seals of the world. Oxford University Press, Oxford, pp 16–19, 51–54Google Scholar
- Rand RW (1959) The Cape fur seal (Arctocephalus pusillus): distribution, abundance and feeding habits off the south western coast of the Cape province. Invest Rep Div Fish SA 34:75Google Scholar
- Repenning CA, Peterson RS, Hubbs CL (1971) Contributions to the systematics of the southern fur seals with particular reference to the Juan Fernandez and Guadalupe species. In: Burt WH (ed) Antarctic pinnipedia. American Geophysical union, Washington DC, pp 1–52Google Scholar
- Sambrook J, Fritsch EF, Maniatis T (1989) Molecular cloning: a laboratory manual, 2nd edn. Cold Spring Harbor Laboratory Press, New YorkGoogle Scholar
- Schneider S, Roessli D, Excoffier L (2000) Arlequin ver. 2.000: A software for population genetics data analysis. Genetics and Biometry Laboratory, University of Geneva, SwitzerlandGoogle Scholar
- Shaughnessy PD (1984) Historical population levels of seals and seabirds on islands off Southern Africa, with special reference to Seal Island, False Bay. Invest Rep Sea Fish Research Inst SA 127:61Google Scholar
- Swofford DL (2002) PAUP* Phylogeny analysis using parsimony (*and other methods), version 4. 0b10. Sinauer Association, Inc., Sutherland, MAGoogle Scholar