Abstract:
Understanding the effects of human exploitation on the genetic composition of wild populations is
important for predicting species persistence and adaptive potential. We therefore investigated the
genetic legacy of large-scale commercial harvesting by reconstructing, on a global scale, the recent
demographic history of the Antarctic fur seal (Arctocephalus gazella), a species that was hunted to the
brink of extinction by 18th and 19th century sealers. Molecular genetic data from over 2,000 individuals
sampled from all eight major breeding locations across the species’ circumpolar geographic distribution,
show that at least four relict populations around Antarctica survived commercial hunting. Coalescent
simulations suggest that all of these populations experienced severe bottlenecks down to effective
population sizes of around 150–200. Nevertheless, comparably high levels of neutral genetic variability
were retained as these declines are unlikely to have been strong enough to deplete allelic richness
by more than around 15%. These findings suggest that even dramatic short-term declines need not
necessarily result in major losses of diversity, and explain the apparent contradiction between the high
genetic diversity of this species and its extreme exploitation history.
