Population genetics of a snail species complex in the British Isles:Littorina saxatilis (Olivi), L-neglecta bean and L-tenebrosa (Montagu),using SSCP analysis of cytochrome-B gene fragments

摘要

The intertidal snail Littorina,saxntilis displays a range of shell morphologies associated with a variety of habitats. Since morphology has an environmental and genetic basis, shell-based taxonomy may not accurately reflect genetic relationships. We explored genetic structure among adjacent populations of L. saxatilis (the robust open-shore type). L. neglecta (the tiny barnacle-dwelling type) and L. tenebrosa (the fragile brackish-water type), at nine sites in Britain. Using single-strand conformational polymorphism analysis of a 375bp fragment of cytochrome-b we found no evidence of species distinction. In AMOVA tests significant variation was contained among populations (68%;,) and among individuals (32%, both P < 0.001), and insignificant variation was found among ecotypes. Genetic patterns suggested gene flow among ecotypes over small scales and a strong random input over larger scales.