Divergent evolutionary processes associated with colonization of offshore islands

• Published in: Molecular Ecology
• Main Authors: Martínková, Natália, Barnett, Ross, Cucchi, Thomas, Struchen, Rahel, Pascal, Marine, Pascal, Michel, Fischer, Martin C., Higham, Thomas, Brace, Selina, Ho, Simon Y. W., Quéré, Jean‐Pierre, O'Higgins, Paul, Excoffier, Laurent, Heckel, Gerald, Rus Hoelzel, A., Dobney, Keith M., Searle, Jeremy B.
• Other Authors: Arts and Humanities Research Council
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2013
• Subjects: Ark the; Common vole
• Online Access: http://dx.doi.org/10.1111/mec.12462; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fmec.12462; https://onlinelibrary.wiley.com/doi/pdf/10.1111/mec.12462; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/mec.12462

Abstract Oceanic islands have been a test ground for evolutionary theory, but here, we focus on the possibilities for evolutionary study created by offshore islands. These can be colonized through various means and by a wide range of species, including those with low dispersal capabilities. We use morphology, modern and ancient sequences of cytochrome b ( cytb ) and microsatellite genotypes to examine colonization history and evolutionary change associated with occupation of the O rkney archipelago by the common vole ( M icrotus arvalis ), a species found in continental E urope but not in B ritain. Among possible colonization scenarios, our results are most consistent with human introduction at least 5100 bp (confirmed by radiocarbon dating). We used approximate B ayesian computation of population history to infer the coast of Belgium as the possible source and estimated the evolutionary timescale using a Bayesian coalescent approach. We showed substantial morphological divergence of the island populations, including a size increase presumably driven by selection and reduced microsatellite variation likely reflecting founder events and genetic drift. More surprisingly, our results suggest that a recent and widespread cytb replacement event in the continental source area purged cytb variation there, whereas the ancestral diversity is largely retained in the colonized islands as a genetic ‘ark’. The replacement event in the continental M . arvalis was probably triggered by anthropogenic causes (land‐use change). Our studies illustrate that small offshore islands can act as field laboratories for studying various evolutionary processes over relatively short timescales, informing about the mainland source area as well as the island.