Islands as refugia of <Emphasis Type="Italic">Trifolium repens</Emphasis> genetic diversity |
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Authors: | Serene Hargreaves Nigel Maxted Ryoko Hirano Michael Abberton Leif Skøt Brian V Ford-Lloyd |
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Institution: | (1) University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK;(2) Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Gogerddan, Aberystwyth, Ceredigion, SY23 3EB, UK |
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Abstract: | Island populations are often thought to be more susceptible to the loss of genetic diversity as a consequence of limited population
size and genetic drift, greater susceptibility to detrimental stochastic events and low levels of immigration. However the
geographic isolation of islands may create refuges for native crop species whose genetic diversity is threatened from the
genetic erosion occurring in mainland areas as a result of crop-wild gene flow and genetic swamping. Many UK islands remain
uncharacterised in terms of plant genetic diversity. In this study we compared the genetic diversity of mainland populations
and landraces of Trifolium repens with wild populations collected from the islands surrounding the UK, including the island of Hirta in the St Kildan archipelago.
Individuals from St Kilda represent a unique conservation resource, with populations both highly differentiated from UK mainland
populations and genetically distinct from cultivated varieties, whilst able to retain diversity through limited human influence
on the islands. In contrast, there is relative genetic similarity of wild UK populations to cultivated forms highlighted in
mainland populations, but with geographic barriers preventing complete homogenisation of the mainland UK genepool. We underline
the need for conservation priorities to include common species that are threatened by gene flow from cultivation, and draw
attention to the potential of islands to preserve natural levels of genetic diversity. |
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