Selection in the polymorphic land snail Cepæa nemoralis
Selection in the polymorphic land snail Cepæa nemoralis
复制标题
多态性陆地蜗牛 Cepæa nemoralis 的选择
作者：
A. Cain;P. Sheppard
正如戴弗（Diver，1940）所指出的，动植物自然种群的结构以及种群内部和种群之间的变异需要更多的研究。沿着这条路线进行的研究沿着是特别重要的，因为他已经获得了证据，证明许多表面上连续的自然种群被分解成小的繁殖群落，从而提供了遗传漂变的条件，正如休厄尔·赖特（Sewall Wright，1940）所建议的那样，如果遗传漂变有效的话，就可能发生。Diver指出，根据他对Cepeea nemoralis（L.）和C. hortensis（穆尔.）他没有发现任何迹象表明贝壳颜色和条纹的变化具有任何选择价值。他认为，由于非随机交配，这些小的繁殖群落彼此之间表现出明确的分歧，但他对这种分歧没有通过遗传漂变进一步发展表示惊讶（1940，第312页）。本文的目的是研究选择和漂变在决定不同颜色和带型分布中的相对重要性。[咒语]相反，我们发现，它们具有确定的选择值，与环境有关，决定不同种群的总体面貌，从而决定它们的基因比率。虽然每个种群内的小型近亲繁殖群落可能在颜色和带型上彼此不同，但由于自然选择的影响，这种随机的差异不会持续很久。
THE structure of natural populations of animals and plants and of variation both within and between colonies needs more study as Diver (1940) has pointed out. Research along these lines is of particular importance because of the evidence he has obtained that many, apparently continuous, natural populations are broken up into small breeding-communities, giving the conditions in which genetic drift, as suggested by Sewall Wright (e.g. 1940), might be expected to occur if it were operative. Diver has stated that from his observations on populations of Cepeea nemoralis (L.) and C. hortensis (MUll.) he obtained no indications that the variations in shell colour and banding have any selective value. He considers that these small breeding-communities show definite divergences from each other because of non-random mating, but expresses surprise (1940, p. 312) that such divergences have not proceeded further by means of genetical drift. The purpose of this paper is to describe an investigation into this problem of the relative importance of selection and drift in determining the distribution of different colour and banding patterns in C. nemoralis. We find, on the contrary, that they have definite selective values, related to the environment, determining the general aspect of different populations and therefore of their gene ratios. Although small inbreeding communities within each population may diverge from one another in colour and banding patterns, this random divergence cannot proceed far, because of the effects of natural selection.