The variation of Cepaea nemoralis in three Pyrenean valleys
The variation of Cepaea nemoralis in three Pyrenean valleys
复制标题
三个比利牛斯山谷的 Cepaea nemoralis 的变化
作者：
R. Cameron;M. Carter;F. Haynes
在比利牛斯山的三个山谷采集了Cepaea nemoralis（L）样品，研究了影响壳色和带型多态性变异的因素。植物学证据已被用来得出关于每个地点的气候和生境的结论。a.sl.），C. nemoralis的变化表明气候选择的作用。黄色和无条纹的贝壳的频率随海拔的增加而增加，在所有亚高山气候条件下（海拔1450米以上）的种群中处于或接近固定状态。白唇贝的出现频率随海拔高度的变化而变化，其变化方式更为复杂，带状白唇贝在谷底常见，而无带状白唇贝在谷底常见;所有白唇贝在中间海拔高度都很罕见。在Jueu的林地样本有较高的频率比那些从开放的栖息地在可比海拔的粉红色和unbanded贝壳，这表明操作的视觉选择的crypsis.In the valley of the Noguera Ribagorzana，south of the分水岭（采样从750至1760米），还有海拔和栖息地对形态频率的影响。粉红色和带状贝壳仅在山区（1300米以上）出现频率较高。而在地中海地区（750-900米）。有非常高的频率的黄色和有效的未绑定的外壳。在这两个极端之间有变化的颜色轨迹与栖息地，棕色的贝壳发生在高频率的密度和阴影habitations.The第三个山谷采样，即Noguera de Tort，加入Noguera Ribagorzana，并包含一个类似的范围内的栖息地和植被带，但不显示相同的模式的变化形态频率。尽管有证据表明气候选择作用于C. Nemoralis种群在比利牛斯山脉，有一个小的一致性，在不同的山谷，从同一植被带种群之间的形态频率。有人建议，考虑到区域内的气候变化和人口的过去的历史是必要的，以占观察到的变化。
SummarySamples of Cepaea nemoralis (L) have been made in three Pyrenean valleys to study factors influencing variation in the shell colour and banding polymorphism. Botanical evidence has been used to draw conclusions about the climate and habitat of each site.In the Jueu valley, north of the Pyrenean watershed (sampled from 750 to 1900 m. a.sl.), morph frequencies of C. nemoralis vary in such a way as to suggest the operation of climatic selection. The frequencies of yellow and unbanded shells increase with altitude, and are at or near fixation in all populations subject to sub-alpine climatic conditions (over 1450 m.). Frequencies of white-lipped shells vary with altitude in a more complex way, banded white-lipped shells being frequent at the base of the valley, and unbanded ones at the head ; all white-lipped shells are rare in the intermediate altitudes. Woodland samples in the Jueu have higher frequencies of pink and unbanded shells than those from open habitats at comparable altitudes, suggesting the operation of visual selection for crypsis.In the valley of the Noguera Ribagorzana, south of the watershed (sampled from 750 to 1760 m.), there are also altitudinal and habitat influences on morph frequencies. Pink and banded shells occur at high frequencies only in the montane zone (above 1300 m.) while in the Mediterranean zone (750–900 m.) there are very high frequencies of yellow and effectively unbanded shells. Between these extremes there is variation at the colour locus with habitat, brown shells occurring at high frequencies in the denser and more shaded habitats.The third valley sampled, that of the Noguera de Tort, joins the Noguera Ribagorzana, and contains a similar range of habitats and vegetation zones, but does not show the same pattern of variation in morph frequencies. There is some variation with altitude, but the pattern is not nearly as clear as in the other two valleys.In spite of the evidence that climatic selection is acting on C. nemoralis populations in the Pyrenees, there is little consistency in morph frequencies between populations from the same vegetation zone in different valleys. It is suggested that consideration of variations in climate within zones and of the past history of the populations is necessary to account for the variation observed.