Parsons Karen E
Department of Zoology, University of Western Australia, Nedlands, Western Australia 6907, Australia e-mail:
Oecologia. 1997 May;110(4):461-471. doi: 10.1007/s004420050181.
Species with contrasting abilities for dispersal may adopt different strategies in response to wide ranges of environmental conditions. These strategies were investigated here by comparisons of phenotypic differentiation and plasticity in the gastropods Austrocochlea constricta and Bembicium vittatum, which coexist in a range of intertidal habitats on the Abrolhos Islands and Albany in Western Australia. They differ in their potential for larval dispersal, A. constricta having a short mobile planktonic stage and B. vittatum developing directly from benthic eggs. Levels of among-population variation in shell shape and maximum size did not differ between the species, or between locations subject to contrasting levels of gene flow in the case of A. constricta. Results of a common garden translocation experiment, coupled with those of previous breeding experiments, suggest that variation in shape is predominantly genetically determined in B. vittatum, but plastic in A. constricta. Plasticity of shape in A. constricta was most pronounced at Albany, where previous data suggested the widest gene flow, and was greater than in B. vittatum at both locations. Change of shape in A. constricta subsequent to translocation was related to growth rate, a trait which was also more plastic in this species than in B. vittatum. The results agree with the notion that wide dispersal enhances physiological flexibility, while restricted dispersal promotes local genetic adaptation, but disagree with the hypothesis that wide dispersal promotes phenotypic homogeneity.
具有不同扩散能力的物种可能会采取不同的策略来应对广泛的环境条件。在此，我们通过比较腹足纲动物澳洲耳螺（Austrocochlea constricta）和带纹滨螺（Bembicium vittatum）的表型分化和可塑性来研究这些策略。这两种腹足纲动物共存于西澳大利亚阿伯罗霍斯群岛和奥尔巴尼的一系列潮间带栖息地。它们在幼体扩散潜力方面存在差异，澳洲耳螺有一个短暂的浮游移动阶段，而带纹滨螺则直接从底栖卵发育而来。在壳形和最大尺寸方面，种群间的变异水平在这两个物种之间没有差异，对于澳洲耳螺来说，在基因流动水平不同的地点之间也没有差异。一项共同花园移植实验的结果，再加上之前的繁殖实验结果，表明带纹滨螺的形状变异主要由基因决定，而澳洲耳螺的形状变异具有可塑性。澳洲耳螺形状的可塑性在奥尔巴尼最为明显，此前的数据表明那里的基因流动最广泛，并且在两个地点都比带纹滨螺的可塑性更大。移植后澳洲耳螺形状的变化与生长速率有关，在这个物种中，生长速率这一特征的可塑性也比带纹滨螺更大。这些结果与广泛扩散增强生理灵活性、而有限扩散促进局部遗传适应的观点一致，但与广泛扩散促进表型同质性的假设不一致。
