Ameliorating the impacts of climate change on communities requires understanding the mechanisms of change and applying them to predict future responses. One way to prioritize efforts is to identify biotic multipliers, which are species that are sensitive to climate change and disproportionately alter communities. We first evaluate the mechanisms underlying the occupancy dynamics of marbled salamanders, a key predator in temporary ponds in the eastern United States We use long-term data to evaluate four mechanistic hypotheses proposed to explain occupancy patterns, including autumn flooding, overwintering predation, freezing, and winterkill from oxygen depletion. Results suggest that winterkill and fall flooding best explain marbled salamander occupancy patterns. A field introduction experiment supports the importance of winterkill via hypoxia rather than freezing in determining overwinter survival and rejects dispersal limitation as a mechanism preventing establishment. We build climate-based correlative models that describe salamander occupancy across ponds and years at two latitudinally divergent sites, a southern and middle site, with and without field-collected habitat characteristics. Correlative models with climate and habitat variation described occupancy patterns better than climate-only models for each site, but poorly predicted occupancy patterns at the site not used for model development. We next built hybrid mechanistic metapopulation occupancy models that incorporated flooding and winterkill mechanisms. Although hybrid models did not describe observed site-specific occupancy dynamics better than correlative models, they better predicted the other site's dynamics, revealing a performance trade-off between model types. Under future climate scenarios, models predict an increased occupancy of marbled salamanders, especially at the middle site, and expansion at a northern site beyond the northern range boundary. Evidence for the climate sensitivity of marbled salamanders combined with their disproportionate ecological impacts suggests that they might act as biotic multipliers of climate change in temporary ponds. More generally, we predict that top aquatic vertebrate predators will expand into temperate-boreal lakes as climate change reduces winterkill worldwide. Predaceous species with life histories sensitive to winter temperatures provide good candidates for identifying additional biotic multipliers. Building models that include biological mechanisms for key species such as biotic multipliers could better predict broad changes in communities and design effective conservation actions.

中文翻译：

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利用机制洞察来预测气候引起的主要水生捕食者的扩张

减轻气候变化对社区的影响需要了解变化的机制并应用它们来预测未来的应对措施。确定工作优先顺序的一种方法是确定生物倍增者，即对气候变化敏感并不成比例地改变群落的物种。我们首先评估大理石蝾螈占据动态的机制，大理石蝾螈是美国东部临时池塘的主要捕食者。我们使用长期数据来评估为解释占据模式而提出的四种机制假设，包括秋季洪水、越冬捕食、冰冻、以及因缺氧而导致的冻死。结果表明，冬季死亡和秋季洪水最能解释大理石蝾螈的占据模式。现场引入实验支持通过缺氧而不是冷冻来决定越冬生存的冬杀的重要性，并拒绝将扩散限制作为阻止建立的机制。我们建立了基于气候的相关模型，描述蝾螈在两个纬度不同的地点（南部和中部地点）跨池塘和年份的占用情况，有或没有现场收集的栖息地特征。与气候和栖息地变化相关的模型比仅气候模型更好地描述了每个地点的占用模式，但对未用于模型开发的地点的占用模式的预测较差。接下来，我们建立了混合机械种群占据模型，其中结合了洪水和冬杀机制。尽管混合模型没有比相关模型更好地描述观察到的特定地点的占用动态，但它们更好地预测了其他地点的动态，揭示了模型类型之间的性能权衡。在未来的气候情景下，模型预测大理石蝾螈的数量将会增加，特别是在中部地点，并且在北部地点扩展到北部范围边界之外。大理石蝾螈对气候敏感的证据及其不成比例的生态影响表明，它们可能在临时池塘中充当气候变化的生物倍增器。更一般地说，我们预测，随着气候变化减少全球冻死率，顶级水生脊椎动物捕食者将扩展到温带-北方湖泊。生活史对冬季温度敏感的掠食性物种为识别其他生物倍增因子提供了良好的候选者。建立包括生物倍增器等关键物种的生物机制的模型可以更好地预测群落的广泛变化并设计有效的保护行动。