A global cline in a colour polymorphism suggests a limited contribution of gene flow towards the recovery of a heavily exploited marine mammal

• Published in: Royal Society Open Science
• Main Authors: Hoffman, Jakobus, Bauer, E., Paijmans, J., Humble, E., Beckmann, L., Kubetschek, C., Christaller, F., Kröcker, N., Fuchs, B., Moreras, A., Shihlomule, Y., Bester, N., Cleary, A., de Bruyn, P. J. N., Forcada, J., Goebel, M. E., Goldsworthy, S. D., Guinet, Christophe, Hoelzel, A. R., Lydersen, C., Kovacs, K. M., Lowther, A.
• Other Authors: Department of Animal Behaviour, Universität Bielefeld, Department of Zoology and Entomology Pretoria, University of Pretoria South Africa, Norwegian Polar Institute, British Antarctic Survey NERC UK, Antarctic Ecosystem Research Division, National Oceanic and Atmospheric Administration (NOAA)-National Marine Fisheries Service, South Australian Research and Development Institute Australia, Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Durham University
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: colour polymorphism; population structure; melanocortin 1 receptor gene; fur seal; pinniped; [SDE]Environmental Sciences; Antarctic; Bouvetøya; Indian; South Shetland Islands; The Antarctic; Antarc*; Antarctic Fur Seal; Arctocephalus gazella; Marion Island
• Online Access: https://hal.science/hal-02263605; https://doi.org/10.1098/rsos.181227

International audience Evaluating how populations are connected by migration is important for understanding species resilience because gene flow can facilitate recovery from demographic declines. We therefore investigated the extent to which migration may have contributed to the global recovery of the Antarctic fur seal (Arctocephalus gazella), a circumpolar distributed marine mammal that was brought to the brink of extinction by the sealing industry in the eighteenth and nineteenth centuries. It is widely believed that animals emigrating from South Georgia, where a relict population escaped sealing, contributed to the re-establishment of formerly occupied breeding colonies across the geographical range of the species. To investigate this, we interrogated a genetic polymorphism (S291F) in the melanocortin 1 receptor gene, which is responsible for a cream-coloured phenotype that is relatively abundant at South Georgia and which appears to have recently spread to localities as far afield as Marion Island in the sub-Antarctic Indian Ocean. By sequencing a short region of this gene in 1492 pups from eight breeding colonies, we showed that S291F frequency rapidly declines with increasing geographical distance from South Georgia, consistent with locally restricted gene flow from South Georgia mainly to the South Shetland Islands and Bouvetøya. The S291F allele was not detected farther afield, suggesting that although emigrants from South Georgia may have been locally important, they are unlikely to have played a major role in the recovery of geographically more distant populations.