Journal ArticleDOI
Sand-Dune Populations of Cepaea nemoralis (L.)
TLDR
A survey of duneland populations of the polymorphic snail Cepaea nemoralis, based on 170 samples from 53 localities on the British and Irish coasts, shows an overall distribution of morph frequencies consistent with the action of visual selection as discussed by the authors.Abstract:
A survey of duneland populations of the polymorphic snail Cepaea nemoralis, based on 170 samples from 53 localities on the British and Irish coasts, shows an overall distribution of morph frequencies consistent with the action of visual selection. Some geographical trends of variation can be discerned, but there is great variation, often over short distances within one group of dunes. A detailed investigation of this has been made at Point of Air, Flintshire. Here and at several other dune systems there is an association of the occurrence of dark browns with complex topography which suggests that they are favoured by very local climatic effects caused by the accumulation of cold air. If local temperature or other climatic factors is effective, the apparent agreement of duneland populations with what is expected as a result of visual selection may be misleading.read more
Citations
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Journal ArticleDOI
Polymorphism in Cepaea: A Problem with Too Many Solutions?
TL;DR: The most important lesson to be gained from an intensive study of the Cepaea polymorphism is that many types of evolutionary force act upon it and that their relative importance varies between different polymorphic loci, or even when the same locus is studied in different populations.
Journal ArticleDOI
Colour, sunlight and internal temperatures in the land-snail Cepaea nemoralis (L.).
TL;DR: Mercury-filled shells and live snails of different colours were exposed to sunlight and large differences in pigmentation led to more pronounced differences in temperatures than did small differences.
Journal ArticleDOI
A two–stage model for Cepaea polymorphism
TL;DR: A simple simulation shows that migration coupled with selection which fluctuates but is not centripetal, may retain polymorphism for sufficiently long to account for the patterns the authors see today.
Journal ArticleDOI
Ecological Genetics and Natural Selection in Molluscs Climatic selection has an important effect on some patterns of gene distribution in snail populations
TL;DR: Analysis of 500,000 C. nemoralis snails from throughout Europe shows that there is a strong positive association between gene frequencies at the shell color locus and mean summer temperature, but that no climatic correlations are obvious at other loci.
References
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The climate near the ground
TL;DR: In this article, the effect of low plant cover on the surface air layer of a level ground without vegetation was analyzed. And the influence of topography on the microclimate was investigated.
Journal ArticleDOI
Selection in the polymorphic land snail Cepaea nemoralis.
TL;DR: An investigation into the problem of the relative importance of selection and drift in determining the distribution of different colour and banding patterns in C. nemoralis finds that they have definite selective values, related to the environment, determining the general aspect of different populations and therefore of their gene ratios.
Journal ArticleDOI
Area Effects in Cepaea
Arthur James Cain,John D. Currey +1 more
TL;DR: The snails Cepaea nemoralis and C. hortensis are remarkable for an extensive and stable polymorphism involving the colour and banding of the shell, but it is not clear that the area effects are caused by some form of selection, but the topography, geology and vegetation of the Marlborough Downs gives no clue to what this could be for banding.