Divergent evolutionary processes associated with colonization of offshore islands

Natalia Martinkova (1, 2) , Ross Barnett (1, 3, 4) , Thomas Cucchi (4, 5) , Rahel Struchen (6) , Michel Pascal (7) , Martin C Fischer (6, 8) , Thomas Higham (9) , Selina Brace (10) , Simon Y.W. Ho (11) , Jean-Pierre Quere (12) , Paul O' Higgins (13) , Laurent Excoffier (6, 8) , Gerald Heckel (6, 8) , A. Rus Hoelzel (4) , Keith M. Dobney (4, 5) , Jeremy B. Searle (13, 14)

1 University of York [York, UK]
2 CAS - Czech Academy of Sciences [Prague]
3 Sch Biol & Biomed Sci
4 Durham University
5 University of Aberdeen
6 UNIBE - Universität Bern / University of Bern
7 ESE - Écologie et santé des écosystèmes
8 Swiss Inst Bioinformat
9 Oxford Radiocarbon Accelerator Unit
10 Egham TW20 0EX
11 NSW 2006
12 UMR CBGP - Centre de Biologie pour la Gestion des Populations
13 York YO10 5DD
14 Weill Medical College of Cornell University [New York]

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 Orkney archipelago by the common vole (Microtus arvalis), a species found in continental Europe but not in Britain. Among possible colonization scenarios, our results are most consistent with human introduction at least 5100bp (confirmed by radiocarbon dating). We used approximate Bayesian 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.

Mots clés: demographic analysis; genetic replacement; island colonization; Microtus arvalis; phylogeography; vole microtus-arvalis; common vole; mitochondrial-dna; population-growth; phylogenetic analyses; mainland populations; molecular phylogeny; statistical tests; genetic diversity; late-pleistocene; genetics; lattre p; agriculture ecosystems & environment

Domaines: Sciences du Vivant [q-bio]

Natalia Martinkova, Ross Barnett, Thomas Cucchi, Rahel Struchen, Michel Pascal, et al.. Divergent evolutionary processes associated with colonization of offshore islands. Molecular Ecology, 2013, 22 (20), pp.5205-5220. ⟨10.1111/mec.12462⟩. ⟨hal-01210192⟩