Habitat deterioration promotes the evolution of direct development in metamorphosing species

Although metamorphosis is widespread in the animal kingdom, several species have evolved life cycle modifications to avoid complete metamorphosis. Some species, e.g., many salamanders and newts, have deleted the adult stage via a process called paedomorphosis. Others, e.g., some frog species and marine invertebrates, no longer have a distinct larval stage and reach maturation via direct development. Here we study which ecological conditions can lead to the loss of metamorphosis via the evolution of direct development. To do so, we use size-structured consumer-resource models in conjunction with the adaptive-dynamics approach. In case the larval habitat deteriorates, individuals will produce larger offspring and in concert accelerate metamorphosis. While this leads to the evolutionary transition from metamorphosis to direct development when the adult habitat is highly favourable, the population will go extinct in case the adult habitat does not provide sufficient food in order to escape ...尽管变态发育（metamorphosis）在动物界广泛存在，但已有多个物种演化出生活史调控修饰策略，以规避完全变态发育。部分物种（如多数蝾螈与真螈）通过幼态持续（paedomorphosis）这一演化机制直接省略成虫阶段；另有部分类群（如部分蛙类与海洋无脊椎动物）则不再具备明确的幼虫阶段，通过直接发育路径完成成熟过程。本研究旨在探究何种生态条件可通过直接发育的演化过程，引发变态发育的丢失。为此，本研究结合自适应动力学（adaptive-dynamics）方法，采用体型结构化的消费者-资源模型。当幼虫栖息地质量退化时，种群个体将产生体型更大的后代，并同步加快变态发育进程。当成虫栖息地环境极为优越时，该演化路径会推动类群从变态发育向直接发育过渡；但若成虫栖息地无法提供充足食物以规避相关困境时，种群则会走向灭绝……