Use of multiple markers demonstrates a cryptic western refugium and postglacial
colonisation routes of Atlantic salmon (Salmo salar L.) in northwest Europe |
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Authors: | A K Finnegan A M Griffiths R A King G Machado-Schiaffino J-P Porcher E Garcia-Vazquez D Bright J R Stevens |
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Institution: | 1.School of Biosciences, University of
Exeter, Exeter, Devon, UK;2.Departmento Biología Funcional,
Facultad de Medicina, Universidad de Oviedo, Oviedo, Spain;3.Office National de l''Eau et des Milieux
Aquatiques, Vincennes, France;4.Westcountry Rivers Trust, Kyl Cober Parc,
Stoke Climsland, Cornwall, Callington, UK |
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Abstract: | Glacial and postglacial processes are known to be important determinants of contemporary
population structuring for many species. In Europe, refugia in the Italian, Balkan and
Iberian peninsulas are believed to be the main sources of species colonising northern
Europe after the glacial retreat; however, there is increasing evidence of small, cryptic
refugia existing north of these for many cold-tolerant species. This study examined the
glacial history of Atlantic salmon in western Europe using two independent classes of
molecular markers, microsatellites (nuclear) and mitochondrial DNA variation. Alongside
the well-documented refuge in the Iberian Peninsula, evidence for a cryptic refuge in
northwest France is also presented. Critically, methods utilised to estimate divergence
times between the refugia indicated that salmon in these two regions had diverged a long
time before the last glacial maximum; coalescence analysis (as implemented in the program
IMa2) estimated divergence times at around 60 000 years before present. Through the
examination of haplotype frequencies, previously glaciated areas of northwest Europe, that
is, Britain and Ireland, appear to have been colonised from salmon expanding out of both
refugia, with the southwest of England being the primary contact zone and exhibiting the
highest genetic diversity. |
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Keywords: | phylogeography refugia microsatellite haplotype ND1 gene |
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