title: Mixing of porpoise ecotypes in southwestern UK waters revealed by genetic profiling.
abstract: Contact zones between ecotypes are windows for understanding how species may react to climate changes. Here, we analysed the fine-scale genetic and morphological variation in harbour porpoises (Phocoena phocoena) around the UK by genotyping 591 stranded animals at nine microsatellite loci. The data were integrated with a prior study to map at high resolution the contact zone between two previously identified ecotypes meeting in the northern Bay of Biscay. Clustering and spatial analyses revealed that UK porpoises are derived from two genetic pools with porpoises from the southwestern UK being genetically differentiated, and having larger body sizes compared to those of other UK areas. Southwestern UK porpoises showed admixed ancestry between southern and northern ecotypes with a contact zone extending from the northern Bay of Biscay to the Celtic Sea and Channel. Around the UK, ancestry blends from one genetic group to the other along a southwest--northeast axis, correlating with body size variation, consistent with previously reported morphological differences between the two ecotypes. We also detected isolation by distance among juveniles but not in adults, suggesting that stranded juveniles display reduced intergenerational dispersal. The fine-scale structure of this admixture zone raises the question of how it will respond to future climate change and provides a reference point for further study.
authors.affiliation: Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, PO Box 11103 CC, Groningen, The Netherlands; School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Michaël C
authors.identifier: 0000-0003-1156-4154
authors.initials: MC
authors.lastname: Fontaine
authors.affiliation: Institute of Zoology, Zoological Society of London, London NW1 4RY, UK; Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
authors.forename: Oliver
authors.initials: O
authors.lastname: Thatcher
authors.affiliation: EnviroSPACE Laboratory, Institute for Environmental Sciences , University of Geneva , Carouge , Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Ray
authors.affiliation: INRA, UMR CBGP, 34988 Montferrier-sur-Lez Cedex , France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Piry
authors.affiliation: Scottish Marine Animal Stranding Scheme , SRUC Veterinary Services , Drummondhill, Stratherrick Road, Inverness IV2 4JZ , UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Brownlow
authors.affiliation: Scottish Marine Animal Stranding Scheme, SRUC Veterinary Services, Drummondhill, Stratherrick Road, Inverness IV2 4JZ, UK; Animal and Plant Health Agency, Polwhele, Truro, Cornwall TR4 9AD, UK.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Davison
authors.affiliation: Institute of Zoology , Zoological Society of London , London NW1 4RY , UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Jepson
authors.affiliation: Institute of Zoology , Zoological Society of London , London NW1 4RY , UK.
authors.forename: Rob
authors.initials: R
authors.lastname: Deaville
authors.affiliation: School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; Institute of Zoology, Zoological Society of London, London NW1 4RY, UK.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Goodman
keywords: admixture; climate change; continuous population; dispersal; ecotype specialization; molecular ecology