Two sympatric ecotypes (‘crab’ and ‘wave’) of Littorina saxatilis are adapted to different microhabitats. It has been claimed, based on the comparison of proteomic differentiation across ontogeny, that the wave ecotype may have evolved by paedomorphosis from an ancestor more similar to the crab ecotype. Here, we test the paedomorphosis hypothesis at a morphological level by comparing crab and wave specimens from two localities using the pattern of shell shape differentiation across ontogeny. The results obtained show a pattern of shell shape differentiation similar to the one observed in previous proteomic studies, but such a pattern could be caused by different modes of evolution, and not necessarily by paedomorphosis. This study emphasizes that in addition to studying the pattern of differentiation, the direction of the evolutionary change across ontogeny has to be analysed before conclusions can be drawn on particular developmental modes of evolution.

中文翻译：

---

比较两种Littorina saxatilis海洋蜗牛生态型沿生长轨迹的形状：通过pa变态的进化测试

Lixtorina saxatilis的两种同伴生态型（“螃蟹”和“波浪”）适应不同的微生境。根据跨个体发育的蛋白质组学差异的比较，已经声称，波生态型可能是由于幼虫的变态而起源于与螃蟹生态型更相似的祖先。在这里，我们通过使用跨个体发育的壳形差异模式比较两个地方的螃蟹和海浪标本，在形态学水平上测试了拟态化假说。所获得的结果显示出与先前蛋白质组学研究中观察到的相似的壳形状分化模式，但是这种模式可能是由不同的进化模式引起的，而不一定是由古怪现象引起的。这项研究强调，除了研究差异化模式之外，