Abstract：
Although there is mounting evidence indicating that the relative timing of predator and prey phenologies determines the outcome of trophic interactions, we still lack a comprehensive understanding of how the environmental context (e.g., abiotic conditions) influences this relationship. Environmental conditions not only frequently drive shifts in phenologies, but they can also affect the very same processes that mediate the effects of phenological shifts on species interactions. Therefore, identifying how environmental conditions shape the effects of phenological shifts is key to predicting community dynamics across a heterogeneous landscape and how they will change with ongoing climate change in the future. Here I tested how environmental conditions shape the effects of phenological shifts by experimentally manipulating temperature, nutrient availability, and relative phenologies in two predator-prey freshwater systems (mole salamander-bronze frog vs. dragonfly larvae-leopard frog). This allowed me to (1) isolate the effects of phenological shifts and different environmental conditions; (2) determine how they interact; and (3) evaluate how consistent these patterns are across different species and environments. I found that delaying prey arrival dramatically increased predation rates, but these effects were contingent on environmental conditions and the predator system. Although nutrient addition and warming both significantly enhanced the effect of arrival time, their effect was qualitatively different across systems: Nutrient addition enhanced the positive effect of early arrival in the dragonfly-leopard frog system, whereas warming enhanced the negative effect of arriving late in the salamander-bronze frog system. Predator responses varied qualitatively across predator-prey systems. Only in the system with a strong gape limitation were predators (salamanders) significantly affected by prey arrival time and this effect varied with environmental context. Correlations between predator and prey demographic rates suggest that this was driven by shifts in initial predator-prey size ratios and a positive feedback between size-specific predation rates and predator growth rates. These results highlight the importance of accounting for temporal and spatial correlations of local environmental conditions and gape limitation when predicting the effects of phenological shifts and climate change on predator-prey systems.
摘要：
尽管有越来越多的证据表明捕食者和猎物物候的相对时间决定了营养相互作用的结果，我们仍然缺乏对环境背景(例如，非生物条件)影响这种关系。环境条件不仅经常驱动物候的变化，但是它们也可以影响介导物候变化对物种相互作用的影响的相同过程。因此,确定环境条件如何塑造物候变化的影响是预测跨异质景观的社区动态以及它们将如何随着未来持续的气候变化而变化的关键。在这里，我测试了环境条件如何通过实验操纵温度来塑造物候变化的影响，营养可用性，和两个捕食者-猎物淡水系统中的相对物候（molesal-青铜蛙与蜻蜓幼虫-豹蛙）。这使我能够（1）隔离物候变化和不同环境条件的影响；（2）确定它们如何相互作用；（3）评估这些模式在不同物种和环境中的一致性。我发现延迟猎物到达会大大增加捕食率，但是这些影响取决于环境条件和捕食者系统。虽然营养添加和增温都显著增强了到达时间的效果，它们的效果在不同系统之间在质量上是不同的：营养添加增强了提前到达蜻蜓-豹蛙系统的积极效果，而变暖则增强了the鱼-青铜蛙系统后期到达的负面影响。捕食者反应在捕食者-食饵系统中定性变化。只有在具有很强间隙限制的系统中，捕食者（salamanders）才受到猎物到达时间的显着影响，并且这种影响随环境而变化。捕食者和猎物人口统计学比率之间的相关性表明，这是由初始捕食者-猎物大小比率的变化以及特定大小的捕食率和捕食者增长率之间的正反馈驱动的。这些结果凸显了在预测物候变化和气候变化对捕食者-食饵系统的影响时，考虑当地环境条件的时空相关性和差距限制的重要性。
