Department of Biology and Biotechnologies "Charles Darwin", Sapienza University of Rome, Zoology - Viale dell'Università 32, 00185 Rome, Italy.
Institut de Systématique, Évolution, Biodiversité, ISYEB, UMR7205 (CNRS, EPHE, MNHN, UPMC), Muséum National d'Histoire Naturelle, Sorbonne Universités, 43 Rue Cuvier, 75231 Paris Cedex 05, France.
Mol Phylogenet Evol. 2021 Feb;155:107014. doi: 10.1016/j.ympev.2020.107014. Epub 2020 Nov 18.
A coiled shell is the most evident feature of the typical Bauplan of a gastropod mollusc. However, at least 54 families independently evolved an apparently simplified shell morphology: the limpet. Species with this largely uncoiled, depressed shell morphology occur in almost every aquatic habitat and are associated to a number of different lifestyles and diets. The marine gastropod family Capulidae includes 18 recognised genera, the large majority of which are coiled, but with a number of limpet-like species. Capulid shell plasticity is also associated to a broad range of feeding ecologies, from obligate suspension feeders to kleptoparasites. To investigate the evolution of the limpet-like shell in the family Capulidae we performed an ancestral state reconstruction analysis on a time-calibrated phylogenetic tree (COI, 16S, and ITS2) including 16 species representing a good deal of its morphological diversity. Our results identified at least three capulid lineages that independently evolved limpet-like shells, suggesting that a recurrent limpetization process characterizes this family. One of the limpet-like genera was undescribed and was here named Cryocapulus n. gen. We suggest that capulids evolved from a coiled suspension feeder lineage and that the shift to kleptoparasitism, which occurred in the family ancestor, may have represented a strategy to save energy through the exploitation of the water current produced by the host. Probably the major drivers of shell evolution in capulids are related to their ecology, most of them being kleptoparasites, include the shape and the kind of host substrate, and lead to the repeated acquisition of a limpet-like shape.
卷曲的壳是典型腹足动物贝壳形态的最显著特征。然而，至少有 54 个科独立进化出了一种明显简化的贝壳形态：石鳖。具有这种几乎不卷曲、扁平贝壳形态的物种出现在几乎所有的水生栖息地，并与许多不同的生活方式和饮食相关。海洋腹足纲 Capulidae 科包括 18 个公认的属，其中绝大多数是卷曲的，但也有一些类似于石鳖的物种。Capulid 壳的可塑性也与广泛的摄食生态有关，从专性悬浮摄食者到盗食寄生者。为了研究 Capulidae 科中类似于石鳖的贝壳的进化，我们对一个经过时间校准的系统发育树（COI、16S 和 ITS2）进行了祖先状态重建分析，该树包括了代表其形态多样性的 16 个物种。我们的结果确定了至少有三个 Capulidae 谱系独立进化出了类似于石鳖的贝壳，这表明一个反复的类似于石鳖的化石化过程是这个科的特征。其中一个类似于石鳖的属是未被描述的，我们将其命名为 Cryocapulus n. gen.。我们认为 Capulidae 是从一个卷曲的悬浮摄食者谱系进化而来的，而在家族祖先中发生的盗食寄生行为可能是一种通过利用宿主产生的水流来节省能量的策略。可能导致 Capulidae 贝壳进化的主要驱动因素与它们的生态有关，其中大多数是盗食寄生者，包括贝壳的形状和宿主基质的种类，并导致了类似于石鳖的形状的重复获得。
