The hypothesis that biotic interactions strengthen toward lower latitudes provides a framework for linking community-scale processes with the macroecological scales that define our biosphere. Despite the importance of this hypothesis for understanding community assembly and ecosystem functioning, the extent to which interaction strength varies across latitude and the effects of this variation on natural communities remain unresolved. Predation in particular is central to ecological and evolutionary dynamics across the globe, yet very few studies explore both community-scale causes and outcomes of predation across latitude. Here we expand beyond prior studies to examine two important components of predation strength: intensity of predation (including multiple dimensions of the predator guild) and impact on prey community biomass and structure, providing one of the most comprehensive examinations of predator–prey interactions across latitude. Using standardized experiments, we tested the hypothesis that predation intensity and impact on prey communities were stronger at lower latitudes. We further assessed prey recruitment to evaluate the potential for this process to mediate predation effects. We used sessile marine invertebrate communities and their fish predators in nearshore environments as a model system, with experiments conducted at 12 sites in four regions spanning the tropics to the subarctic. Our results show clear support for an increase in both predation intensity and impact at lower relative to higher latitudes. The predator guild was more diverse at low latitudes, with higher predation rates, longer interaction durations, and larger predator body sizes, suggesting stronger predation intensity in the tropics. Predation also reduced prey biomass and altered prey composition at low latitudes, with no effects at high latitudes. Although recruitment rates were up to three orders of magnitude higher in the tropics than the subarctic, prey replacement through this process was insufficient to dampen completely the strong impacts of predators in the tropics. Our study provides a novel perspective on the biotic interaction hypothesis, suggesting that multiple components of the predator community likely contribute to predation intensity at low latitudes, with important consequences for the structure of prey communities.

中文翻译：

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更强的捕食强度和对热带猎物群落的影响

生物相互作用向低纬度地区加强的假设为将社区规模过程与定义我们生物圈的宏观生态规模联系起来提供了一个框架。尽管这一假设对于理解群落组装和生态系统功能很重要，但相互作用强度随纬度变化的程度以及这种变化对自然群落的影响仍未得到解决。捕食尤其是全球生态和进化动态的核心，但很少有研究探讨跨纬度捕食的社区规模原因和结果。在这里，我们超越以往的研究扩展到审查的捕食强度的两个重要组成部分：强度捕食（包括捕食公会的多个维度）和影响关于猎物群落生物量和结构的研究，提供了跨纬度捕食者-猎物相互作用的最全面的研究之一。使用标准化实验，我们测试了捕食强度和对猎物群落的影响在低纬度地区更强的假设。我们进一步评估了猎物招募，以评估该过程调节捕食效应的潜力。我们使用近岸环境中的无柄海洋无脊椎动物群落及其鱼类捕食者作为模型系统，并在横跨热带到亚北极的四个地区的 12 个地点进行了实验。我们的结果表明，相对于高纬度地区，低纬度地区的捕食强度和影响都增加了。捕食者公会在低纬度地区更加多样化，捕食率更高，互动持续时间更长，和更大的捕食者体型，表明热带地区的捕食强度更强。捕食还减少了低纬度的猎物生物量并改变了猎物的组成，而在高纬度则没有影响。尽管热带地区的招募率比亚北极地区高出三个数量级，但通过这一过程替换猎物并不足以完全抑制热带捕食者的强烈影响。我们的研究为生物相互作用假设提供了一个新的视角，表明捕食者群落的多个组成部分可能有助于低纬度地区的捕食强度，对猎物群落的结构产生重要影响。在高纬度地区没有影响。尽管热带地区的招募率比亚北极地区高出三个数量级，但通过这一过程替换猎物并不足以完全抑制食肉动物在热带地区的强烈影响。我们的研究为生物相互作用假设提供了一个新的视角，表明捕食者群落的多个组成部分可能有助于低纬度的捕食强度，对猎物群落的结构产生重要影响。在高纬度地区没有影响。尽管热带地区的招募率比亚北极地区高出三个数量级，但通过这一过程替换猎物并不足以完全抑制热带捕食者的强烈影响。我们的研究为生物相互作用假设提供了一个新的视角，表明捕食者群落的多个组成部分可能有助于低纬度的捕食强度，对猎物群落的结构产生重要影响。