THE CONSEQUENCES OF BEING DIFFERENT - SINISTRAL COILING IN CERION
THE CONSEQUENCES OF BEING DIFFERENT - SINISTRAL COILING IN CERION
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DOI：
10.1111/j.1558-5646.1985.tb05701.x
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发表时间：
1985-01-01
期刊：
影响因子：
3.3
通讯作者：
KASSON, B
中科院分区：
文献类型：
--
作者：
GOULD, SJ;YOUNG, ND;KASSON, B
腹足类中右旋的压倒性优势是一个突出而令人费解的现象。少数左旋标本(左盘绕个体)已在许多右旋物种中被发现。在Cerion中只发现了六个左旋贝壳；我们根据五个可用的贝壳进行了分析。我们问，逆对称是否是一种简单的非此即彼的转换，不会对壳的形状产生进一步的影响，或者左旋是否会产生相关的效应，使左旋壳在其他方面不同于它们的右旋壳。这五个左旋壳的大小和盘绕特征都不同，生长较晚，导致孔径相对较小，盘绕轴略有扭曲。我们检测和测量这种影响如下：在多变量形态空间中，左旋者在他们的右旋体中占据外围位置；在单变量分析中，左旋者对于一组涉及协方差模式的性状一致不同，这在十年来对右旋体个体发生和年龄标准化变异的研究中从未见过；Bootstrap过程不能在与真实左旋分布匹配的随机构成的右旋体样本中恢复类似的模式；对卷曲轴的直接X射线测量检测到其在左旋体中的轻微扭曲。我们讨论了这些意想不到的关联对于形态进化的发展制约问题的影响。
The overwhelming predominance of dextral coiling in gastropods is an outstanding and puzzling phenomenon. A few sinistral specimens (left coiling individuals) have been found in many dextral species. Only six sinistral shells have ever been found in Cerion; we base this analysis on the five available shells. We ask whether reversed symmetry is a simple either-or switch without further consequences for shell form, or whether sinistrality engenders associated effects, making left-coiling shells unlike their dextral deme-mates in other ways. All five sinistral shells differ in features of size and coiling late in growth, leading to relatively small apertures and a slight twist in the axis of coiling. We detect and measure this effect as follows: in multivariate morphospace, sinistrals occupy peripheral positions among their dextral deme-mates; in univariate analysis, sinistrals are consistently different for a set of characters involving covariance patterns never before seen in a decade of studies on ontogenetic and age-standardized variation in dextrals; a bootstrap procedure does not recover similar patterns in randomly constituted samples of dextrals matching the true sinistral distribution; direct x-ray measures of the coiling axis detect its slight twist in sinistrals. We discuss the implications of these unsuspected associations for the issues of developmental constraint upon the evolution of morphology.