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.

厘清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科研难题，但其对于精准预测气候变化对物种分布的影响至关重要。本研究针对3种生活史需求各异的湿地繁殖两栖动物种群，探究其在六年极端降水波动周期内的响应规律。该时段兼具重度干旱与强降水、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景。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 model），估算物种的发生动态，以此量化每种两栖动物的集合种群（metapopulation）动态如何受天气、湿地水文周期与鱼类捕食者共存交互作用的调控。研究结果显示，广食性的猪蛙对环境扰动的抗性最强，其定殖与存续过程均不受降水季节波动或与鱼类共存的影响。作为临时湿地特化种的饰纹丛蛙，在低降水时段的存续率与定殖率均有所提升，因此对干旱时段呈现正向响应。而在长周期湿地中，饰纹丛蛙的发生概率极低，这是由于当鱼类存在时其定殖率低下，受捕食者交互作用直接驱动所致。钝口螈对水分可利用性变化最为敏感。本研究区域内，该物种从未在短周期湿地中出现，且其存续概率在干旱期有所下降。与此同时，极端降水也会带来负面影响：洪涝会促使鱼类扩散至孤立湿地，而钝口螈无法在已有鱼类的湿地中完成定殖。本研究证实，水分可利用性变化的生态效应，取决于其与捕食者交互作用及湿地类型的综合影响，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发生建模方法，在旨在厘清调控物种响应环境变异的复杂交互作用的研究目标下，可为其他同类研究系统提供可行的分析范式。