Population genetics of bottlenose dolphins (Tursiops truncatus) from an Anglo-Saxon archaeological site in comparison with modern populations.

Abstract

Bottlenose dolphins {Tursiops truncatus) exhibit a cosmopolitan distribution, being found in temperate and tropical oceans throughout the world. Members of this species in the waters surrounding Britain are the most northerly populations and show a discontinuous modern distribution. The excavation of an Anglo-Saxon site at Flixborough, near the Humber Estuary in eastern England, has yielded the largest archaeological sample of bottlenose dolphin remains yet found in Britain, however, the estuary does not currently support a bottlenose dolphin population. This offers an opportunity to study the temporal dynamics of genetic structure for this species in a region where their conservation and management is of concern. Comparisons of mtDNA control region sequences and microsatellite genotypes from the remains at Flixborough with modern samples from elsewhere in the British Isles and around the world were completed. The results show that the samples from Flixborough form a genetically distinct population from all modern groups, including those around the United Kingdom and Ireland. It is suggested that a local population existed in the Humber Estuary during Anglo-Saxon times, which was most likely established through a founding event and has since become extinct. Possible causes of this local extinction and implications for management of modern populations around the British Isles are discussed. [brace not closed]