Data from: Effects of conditionally expressed phenotypes and environment on amphibian dispersal in nature

Individuals vary greatly in the distance they disperse, and in doing so, strongly affect ecological and evolutionary processes. Dispersal, when viewed as a component of phenotype, can be affected independently or jointly by environment. However, among taxa with complex life cycles that occupy different habitats over ontogeny, the effects of environment on dispersal and the interaction between environment and phenotype remains poorly understood. Here, we conducted a field experiment to measure how dispersal distance was affected by phenotype, environment experienced before and after metamorphosis, and their interaction. We manipulated the environment encountered by a pond-breeding salamander (Ambystoma annulatum) during the aquatic larval stage and again as dispersing terrestrial juveniles. After assaying juvenile phenotype (exploration behavior, body condition, and morphology), we then measured the initial distance dispersed by juveniles. The distance moved by dispersing salamanders was affected by attributes of both larval and juvenile habitat, with salamanders that encountered low quality habitat in either life stage moving the farthest. However, we did not find support for an interactive effect of phenotype and environment affecting the distance moved by dispersers. Interestingly, exploration behavior explained the distance moved by philopatric animals but not dispersing ones. Our findings indicate that the environment experienced before metamorphosis can affect juvenile dispersal behavior, and demonstrates the need to consider dispersal in species with complex life cycles to understand the coupling between local and regional population dynamics.

个体的扩散距离存在显著差异，而扩散行为本身会对生态与进化过程产生强烈影响。若将扩散视为表型（phenotype）的组成部分，则其可受到环境的独立或联合调控。然而，对于那些在个体发育（ontogeny）过程中占据不同栖息地的复杂生活史类群而言，环境对扩散的影响以及环境与表型间的互作机制仍未得到充分阐释。本研究通过野外实验，探究了表型、变态（metamorphosis）前后所经历的环境及其交互作用对扩散距离的影响。我们以环纹钝口螈（Ambystoma annulatum）为研究对象，分别调控其水生幼体阶段以及陆生扩散幼体阶段所遭遇的环境条件。在测定幼体表型（探索行为、身体状况与形态特征）后，我们进一步记录了幼体的初始扩散距离。扩散蝾螈的移动距离同时受到幼体栖息地与陆生幼体栖息地特征的影响，且任一生活史阶段遭遇低质量栖息地的个体，其移动距离均最远。但本研究未发现表型与环境的交互作用对扩散者移动距离存在显著影响的证据。值得注意的是，探索行为可解释恋栖（philopatric）个体的移动距离，但无法解释扩散个体的移动模式。本研究结果表明，变态前经历的环境可显著影响幼体扩散行为，同时也证实：若要理解局域与区域种群动态间的耦合关系，需将扩散过程纳入复杂生活史物种的研究框架之中。