Pappalardo Paula, Rodríguez-Serrano Enrique, Fernández Miriam
Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America; Centro de Conservación Marina, Departamento de Ecología, Pontificia Universidad Católica de Chile, Santiago, Chile.
Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile.
PLoS One. 2014 Apr 8;9(4):e94104. doi: 10.1371/journal.pone.0094104. eCollection 2014.
Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule), which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding) development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in muricids gastropods.
幼虫的发育模式影响着进化过程，并影响海洋无脊椎动物在海洋中的分布。向高纬度地区浮游发育的减少是海洋生物中最常讨论的分布模式之一（索尔森法则），这与冷水域中浮游期延长导致的幼虫死亡率增加有关。然而，有研究表明，成体所占据的基质类型会影响幼虫发育纬度模式的普遍性。为了帮助理解环境如何影响幼虫类型的进化，我们以骨螺科腹足类动物为模型组，评估了幼虫发育与栖息地之间的关联。为实现这一目标，我们收集了关于纬度分布、海水温度、幼虫发育以及成体所占据的基质类型的信息。我们构建了45种骨螺的分子系统发育树，以估计祖先特征状态，并在贝叶斯框架下使用比较方法评估性状之间的关系。我们的结果表明，骨螺的共同祖先很可能具有非浮游（且非摄食）发育方式，生活在硬底质和低温环境中。从这个祖先开始，浮游摄食幼虫进化了三次，一些物种转移到了温暖的温度环境或沙质底质。幼虫发育的进化并非独立于栖息地；在相关进化分析中重建的最可能的进化路径表明，幼虫发育类型在软底质中可能会发生变化，但在硬底质中这种变化极不可能。较低的海水温度与非浮游发育方式相关，支持了索尔森法则。我们展示了环境压力如何有利于特定的幼虫发育模式或幼虫模式之间的转变，并讨论了骨螺科腹足类动物中摄食幼虫的重新获得。
