Adaptive Phenotypic Plasticity in an Aquatic Community

春季在北海道森林外围形成的池塘群落中，梨蛙（Rana pirica）的无尾蝌蚪（Anuran tadoles）和迟发小水螅（Hynobius retardatus）的蝾螈（salamander）幼虫是主要的建立者。在一定条件下，蝾螈幼虫在发育过程中呈宽头形态。娃娃鱼的幼虫头部宽阔，是一种强大的捕食者，有能力吞下同种的幼虫和大嘴巴的蝌蚪。宽头形态被认为是一种适应性表型可塑性。蝌蚪也表现出表型可塑性。当蝌蚪暴露在娃娃鱼幼虫的捕食风险中时，它们会发育出一个肥大的身体。这种肿胀阻止了被有大嘴巴的蝾螈吞下。面包头蝾螈幼体的可塑性和胖胖的蝌蚪幼体的可塑性被认为是捕食者-猎物相互作用的拮抗性共同进化。蝌蚪对群落中其他捕食者表现出另一种诱导防御形态。蜻蜓幼虫是池塘群落中最常见的捕食者之一。当蝌蚪暴露在蜻蜓幼虫的捕食风险中时，它们的尾巴形态会变高。小蝌蚪有两种诱导防御形态。一种是对蝾螈幼虫捕食风险的专门型诱导形态，另一种是对池塘群落中各种捕食物种的通才型诱导形态。

Anuran tadoles of Rana pirica, and salamander larvae of Hynobius retardatus are the founders of the ponds community that are formed in forests peripheral in Hokkaido in spring. The salamander larvae become a broad headed morph in the larval developmental period in certain condition. Larval salamanders having a broad headed-morph are a strong predator that has an ability to swallow conspecific larvae and tadpoles with a large gape size. The broad-headed morph is considered as an adaptive phenotypic plasticity. The tadpoles also exhibit a phenotypic plasticity. The tadpoles develop a bulgy body when they are exposed to the predation risk of the larval salamanders. The bulginess prohibits being swallowed by the salamanders having a large gape. The plasticity of larval salamander, bread-head, and of tadpole, bulgy body, are considered as antagonistic coevolution of predator-prey interaction.The tadpoles exhibit the other type of inducible defense morphology to the other predator species in the community. Dragon fly larvae are one of the commonest predator species in the pond community. The tadpoles develop higher tail morphology when they are exposed to the predation risk of the dragon fly larvae. Tadpoles of R. pirica have two types of inducible defense morphologies. One is the specialist type inducible morphology to the predation risk of the larval salamander, and the other on is the generalist type one to the various other predator species in the pond community.