Data from: Species interactions and the effects of climate variability on a wetland amphibian metacommunity

Disentangling the role that multiple interacting factors have on species responses to shifting climate poses a significant challenge. However, our ability to do so is of utmost importance to predict the effects of climate change on species distributions. We examined how populations of three species of wetland breeding amphibians, which varied in life history requirements, responded to a six-year period of extremely variable in precipitation. This interval was punctuated by both extensive drought and heavy precipitation and flooding, providing a natural experiment to measure community responses to environmental perturbations. We estimated occurrence dynamics using a discrete hidden Markov modeling approach that incorporated information regarding habitat state and predator-prey interactions. This approach allowed us to measure how metapopulation dynamics of each amphibian species was affected by interactions among weather, wetland hydroperiod, and co-occurrence with fish predators. The pig frog, a generalist, proved most resistant to perturbations, with both colonization and persistence being unaffected by seasonal variation in precipitation or co-occurrence with fishes. The ornate chorus frog, an ephemeral wetland specialist, responded positively to periods of drought owing to increased persistence and colonization rates during periods of low-rainfall. Low probabilities of occurrence of the ornate chorus frog in long-duration wetlands were driven by interactions with predators due to low colonization rates when fishes were present. The mole salamander was most sensitive to shifts in water availability. In our study area, this species never occurred in short-duration wetlands and persistence probabilities decreased during periods of drought. At the same time, negative effects occurred with extreme precipitation because flooding facilitated colonization of fishes to isolated wetlands and mole salamanders did not colonize wetlands once fishes were present. We demonstrate that the effects of changes in water availability depend on interactions with predators and wetland type and are influenced by the life history of each of our species. The dynamic species occurrence modeling approach we used offers promise for other systems when the goal is to disentangle the complex interactions that determine species responses to environmental variability.解析多重交互因子对物种响应气候变化的作用机制，是一项极具挑战性的课题；而阐明这一机制，对于预测气候变化对物种分布的影响至关重要。本研究针对3种具有不同生活史需求的湿地繁殖两栖动物种群，探究其对为期6年的极端降水波动的响应。该研究区间穿插了大范围干旱、强降水与洪涝事件，为量化群落对环境扰动的响应提供了天然实验场所。我们采用整合了栖息地状态与捕食者-猎物交互信息的离散隐马尔可夫模型（discrete hidden Markov modeling），估算了物种出现动态。该方法得以量化每种两栖动物的集合种群动态（metapopulation dynamics）如何受天气、湿地水文周期（wetland hydroperiod）以及与鱼类捕食者共存的交互作用影响。研究结果显示，作为广食性物种的猪蛙（pig frog）对环境扰动的抗性最强，其定植与种群存续概率均不受降水季节波动或与鱼类共存的影响。作为临时性湿地特化物种的华丽丛蛙（ornate chorus frog），在干旱时期的响应为正向——低降水时段其种群存续与定植率均有所提升。在长期水文周期湿地中，华丽丛蛙的出现概率较低，这是由于当鱼类存在时其定植率低下，进而受到捕食者交互作用的调控。鼹钝口螈（mole salamander）对水资源可利用性的变化最为敏感。在本研究区域内，该物种从未在短期水文周期湿地中出现，且其种群存续概率在干旱时期有所下降。与此同时，极端降水也会带来负面影响：洪涝灾害会促使鱼类扩散至孤立湿地，而当鱼类存在时，鼹钝口螈无法完成湿地定植。本研究证实，水资源可利用性变化的影响取决于其与捕食者、湿地类型的交互作用，同时也受各研究物种自身生活史特征的调控。我们所采用的动态物种出现建模方法，在旨在解析决定物种响应环境变异的复杂交互作用的其他研究系统中，同样具有应用前景。