Abstract
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.
Highlights
Evaluating the extent to which natural populations are connected by gene flow is important for understanding how species may respond to anthropogenic exploitation [1]
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
An interesting test case is provided by the Antarctic fur seal (Arctocephalus gazella), a pinniped species that breeds on sub-Antarctic islands with 97% of the contemporary population concentrated around South Georgia in the South Atlantic [7]
Summary
Evaluating the extent to which natural populations are connected by gene flow is important for understanding how species may respond to anthropogenic exploitation [1]. An interesting test case is provided by the Antarctic fur seal (Arctocephalus gazella), a pinniped species that breeds on sub-Antarctic islands (figure 1) with 97% of the contemporary population concentrated around South Georgia in the South Atlantic [7]. Antarctic fur seals were subjected to extreme exploitation for their skins during the eighteenth and nineteenth centuries, with over a million seals taken from South Georgia alone [13]. Antarctic fur seal numbers showed little sign of recovery until the 1930s [20], within just a few decades the species had re-occupied all of its former breeding sites and the worldwide population is thought to number around four to six million animals (IUCN Red List, http://www.iucnredlist.org)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
