Spatial structure of shell polychromatism in populations of Cepaea nemoralis: new techniques for an old debate
Spatial structure of shell polychromatism in populations of Cepaea nemoralis: new techniques for an old debate
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DOI：
10.1038/sj.hdy.6800012
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发表时间：
2002-01-01
期刊：
影响因子：
3.8
通讯作者：
Guiller, A
中科院分区：
文献类型：
--
作者：
Bellido, A;Madec, L;Guiller, A
在法国西部（布列塔尼）的Cepaea nemoralis群体中观察到明显的壳多色性。本研究的目的是寻找一个空间结构的外壳功能在这个规模，并推断所观察到的模式的进化过程。我们使用的数据库的形态频率（保留六个复合表型）测量213个样本定期分布在整个研究领域。数据分析基于两种不同的多变量方法，导致以下步骤：（i）在不参考环境条件的情况下，（全局主成分分析：GPCA），其通过采样点之间的相邻关系考虑空间信息（Delaunay三角测量）;（ii）通过两个解释因素来测试环境条件的结构化能力（距离海，海拔）中涉及的冗余分析（RDA）;（iii）搜索的空间结构使用残差的先前的分析，即，在删除环境条件的影响。全局协方差占总方差的26.4%，导致每个表型的高度显著的自相关（步骤1）。从全球分析得出的因子得分的地理绘图显示，结构良好的沿岸的区和强烈的南北内陆分化。RDA表示了总方差的16%，但所有变体并不同等关注。在消除环境影响后，一个重要的空间结构仍然存在，但基本上是由随机过程造成的。我们认为这些最后的现象的重要性。
A conspicuous shell polychromatism is observed in colonies of Cepaea nemoralis from western France (Brittany). The present study is intended to search for a spatial structure of shell features at this scale and to infer evolutionary processes from the observed patterns. We used a database of morph frequencies (six composite phenotypes were retained) measured on 213 samples regularly distributed on the whole studied area. Data analysis was based on two distinct multivariate methods leading to the following steps: (i) to search for a structure without reference to environmental conditions with a method (global principal components analysis: GPCA) which takes into account the spatial information by means of a neighbouring relationship between sampling points (Delaunay triangulation); (ii) to test the structuring power of environmental conditions by means of two explanatory factors (distance from the sea, altitude) involved in a redundancy analysis (RDA); (iii) to search for a spatial structure using residuals of the previous analysis, ie, after removing effects of environmental conditions. Global covariance accounted for 26.4% of the total variance, leading to a highly significant autocorrelation for each phenotype (step 1). Geographical mapping of factorial scores resulting from global analysis showed a well structured littoral zone and a strong southern-northern inland differentiation. Sixteen percent of the total variance was expressed in RDA but all morphs were not equally concerned. After removing environmental effects, a significant spatial structure still remains but was essentially caused by random processes. We argue for the importance of these last phenomena.