捕食者诱导的形态特征决定了一种两栖类幼体的逃逸表现

文献信息

中文摘要

尽管水生动物种间形态多样性常反映与游泳相关的功能权衡，但种内形态变异（常由表型可塑性产生）是否也反映类似权衡仍不清楚。我们利用Rana pirica蝌蚪检验这一假说，该蝌蚪具有蜻蜓诱导的表型（尾部更深）和蝾螈诱导的表型（尾部更深且身体膨大）。快速启动游泳速度在蜻蜓诱导表型中最高，在蝾螈诱导表型中居中，在非诱导表型中最低。由于游泳速度受形态和身体运动努力共同影响，我们量化了运动速度效率（Ems）作为形态对游泳表现影响的指标。两种捕食者诱导表型均表现出高于非诱导表型的Ems，尽管各表型间尾部运动量相似，其中蜻蜓诱导表型值最高。这些结果表明，共有的更深尾部能更有效地将身体运动努力转化为游泳速度，而在蝾螈诱导表型中，这一功能部分被其膨大身体引起的流体阻力增加所抵消，该形态可防止被张口受限的蝾螈幼体吞食。这些结果表明，捕食者诱导的形态涉及游泳逃逸与物理保护之间的功能权衡，并提示此类权衡通过表型可塑性促进形态多样化。

英文摘要

Although interspecific morphological diversity in aquatic animals often reflects swimming-related functional trade-offs, whether intraspecific morphological variation, often generated by phenotypic plasticity, also reflects similar trade-offs remains unclear. We tested this hypothesis using Rana pirica tadpoles, which exhibit a dragonfly-induced phenotype with a deeper tail and a salamander-induced phenotype with both a deeper tail and a swollen body. Fast-start swimming speed was highest in the dragonfly-induced phenotype, intermediate in the salamander-induced phenotype and lowest in the non-induced phenotype. Because swimming speed is influenced by both morphology and body-motion effort, we quantified motion-speed efficiency (Ems ) as an index of morphological effects on swimming performance. Both predator-induced phenotypes exhibited higher Ems than the non-induced phenotype, despite similar tail-motion quantity among phenotypes, with the highest value in the dragonfly-induced phenotype. These results indicate that the shared deeper tail more efficiently converts body-motion effort into swimming speed, whereas in the salamander-induced phenotype, this function is partly offset by increased hydrodynamic drag caused by its swollen body, a morphology that protects against swallowing by gape-limited salamander larvae. These results demonstrate that predator-induced morphologies involve functional trade-offs between swimming escape and physical protection and suggest that such trade-offs contribute to morphological diversification through phenotypic plasticity.