Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
J Exp Biol. 2013 Dec 1;216(Pt 23):4426-34. doi: 10.1242/jeb.091991.
Transitions between aquatic and terrestrial environments are significant steps in vertebrate evolution. These transitions require major changes in many biological functions, including food uptake and transport. The Alpine newt, Ichthyosaura alpestris, is known to show a 'multiphasic lifestyle' where the adult shifts from a terrestrial to an aquatic lifestyle and then back to a terrestrial lifestyle every year as a result of its breeding activity. These transitions correspond to dramatic changes in morphology, physiology and behavior, resulting in distinct aquatic and terrestrial morphotypes. We hypothesized that these shifts go along with changes in prey-capture mechanics to maintain a sufficiently high performance in both environments. We analyzed the prey-capture kinematics in the four possible modes: aquatic strikes in the aquatic phase, terrestrial strikes in the terrestrial phase, aquatic strikes in the terrestrial phase and terrestrial strikes in the aquatic phase. A multivariate comparison detected significant kinematic differences between the phase-specific feeding modes. In both the aquatic and the terrestrial phase, I. alpestris uses a suction-feeding mechanism for capturing prey in water. By contrast, I. alpestris uses a jaw-based grasping mechanism with a kinematic profile similar to the aquatic modes for terrestrial prey-capture in its aquatic phase but an elaborate lingual-based prehension mechanism to capture terrestrial prey in the terrestrial phase. These results exhibit a so-far unknown amount of behavioral plasticity in prey-capture behavior that is tuned to the seasonal demands of performance, and exemplify functional mechanisms behind aquatic-terrestrial transitions in vertebrates.
水生到陆生环境的转变是脊椎动物进化中的重要步骤。这些转变需要许多生物学功能的重大改变，包括食物摄取和运输。高山蝾螈，Ichthyosaura alpestris，以其“多相生活方式”而闻名，即成年个体由于繁殖活动，每年从陆地生活方式转变为水生生活方式，然后再转变回陆地生活方式。这些转变对应于形态、生理和行为的巨大变化，导致明显的水生和陆生形态。我们假设这些转变伴随着捕食力学的变化，以在两种环境中保持足够高的性能。我们分析了四种可能模式下的捕食运动学：水生相的水生攻击、陆生相的陆生攻击、陆生相的水生攻击和水生相的陆生攻击。多变量比较检测到特定相位的摄食模式之间存在显著的运动学差异。在水生相和陆生相中，高山蝾螈都使用吸吮机制在水中捕获猎物。相比之下，高山蝾螈在其水生相中使用基于下颚的抓取机制，其运动学特征类似于水生模式，用于捕获陆生相中的陆生猎物，但在陆生相中使用复杂的基于舌的擒抱机制来捕获陆生猎物。这些结果显示了捕食行为中迄今为止未知的行为可塑性程度，这种可塑性程度是根据性能的季节性需求进行调整的，并例证了脊椎动物水生到陆生转变背后的功能机制。
