Phylogeography and population dynamics of the white-sided dolphin (Lagenorhynchus acutus) in the North Atlantic

Abstract

Highly mobile species in the marine environment may be expected to show little differentiation at the population level, but this is often not the case. Instead cryptic population structure is common, and effective conservation will require an understanding of how these patterns evolve. Here we present an assessment from both sides of the North Atlantic of differentiation among populations of a dolphin species that inhabits mainly pelagic waters, the Atlantic white-sided dolphin. We compare eleven putative populations in the western and eastern North Atlantic at mtDNA and microsatellite DNA loci and find reduced nucleotide diversity and signals for historical bottlenecks and post-bottleneck expansions in all regions. We calculate expansion times to have occurred during the early Holocene, following the last glacial maximum (LGM). We find evidence for connectivity among populations from either side of the North Atlantic, and differentiation between putative populations in the far northeast compared with all other areas sampled. Some data suggest the possibility of separate refugia during the LGM explaining this pattern, although ongoing ecological processes may also be a factor. We discuss the implications for developing effective programs of conservation and management in the context of ongoing anthropogenic impact. © 2014 Springer Science+Business Media Dordrecht.We thank Charlie Shaw, Fernando Gast Harders, Greger Larson and Theresa Mackinven for assistance and facilities. We thank Kelly Robertson, Mogens Andersen, Lasse Fast Jensen, Charlie Potter, Mary Harman, Marjan Addink, Henry van der Es, Kees Moeliker, Ronald Vonk, Peter Nilsson, Steven van der Mije, Paul Jepson, Sverrir D. Halldorsson, Gisli Vikingsson, Anna Roos, Richard Sabin, Rod Penrose, Chris Smeenk, Carl Kinze and the following institutions: Museum of Natural History Rotterdam, Museum of Natural History Leiden, Fisheries and Maritime Museum Denmark, Natural History Museum of Denmark, Natural History Museum London, Natural History Museum Faroe Islands, and the Smithsonian Institution, Stranding Networks from Scotland, England & Wales, The National Oceanic and Atmospheric Administration (NOAA) in the USA, the Maritime Institute in Iceland, the Swedish Museum of Natural History (SMNH) Stockholm, the Department of Contaminant Research, Stockholm, IMARES in Holland and the Marine Research Institute (Ireland), the Heritage Council of Ireland, National Parks and Wildlife Service, INTERREG Ireland-Wales, and the EC-funded BIOCET programme for advice and help with the acquisition of samples. Thanks also to The Alexander von Humboldt Biological Resources Research Institute, the Colombian Institute of Studies Abroad (ICETEX). This project was supported by the Programme Alban, European Union Programme of high level Scholarship for Latin America (Identification Number EO3D17203CO); United Nations Environmental Programme/Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (UNEP/ASCOBANS); The Ustinov College, University of Durham; and the Irish Higher Education Authority. The UK Cetacean Strandings Investigation Programme, from which many samples were acquired, is funded by the UK Department for Environment Food and Rural Affairs, with further financial support from the Scottish Government