Data Science Initiative, University of California, Davis, California, 95616, USA.
Department of Evolution and Ecology, University of California, Davis, California, 95616, USA.
Ecology. 2018 Jan;99(1):29-35. doi: 10.1002/ecy.2064.
Latitudinal gradients in species interactions are widely cited as potential causes or consequences of global patterns of biodiversity. However, mechanistic studies documenting changes in interactions across broad geographic ranges are limited. We surveyed predation intensity on common prey (live amphipods and gastropods) in communities of eelgrass (Zostera marina) at 48 sites across its Northern Hemisphere range, encompassing over 37° of latitude and four continental coastlines. Predation on amphipods declined with latitude on all coasts but declined more strongly along western ocean margins where temperature gradients are steeper. Whereas in situ water temperature at the time of the experiments was uncorrelated with predation, mean annual temperature strongly positively predicted predation, suggesting a more complex mechanism than simply increased metabolic activity at the time of predation. This large-scale biogeographic pattern was modified by local habitat characteristics; predation declined with higher shoot density both among and within sites. Predation rates on gastropods, by contrast, were uniformly low and varied little among sites. The high replication and geographic extent of our study not only provides additional evidence to support biogeographic variation in predation intensity, but also insight into the mechanisms that relate temperature and biogeographic gradients in species interactions.
纬度梯度上的物种相互作用被广泛认为是全球生物多样性模式的潜在原因或结果。然而，记录广泛地理范围内相互作用变化的机制研究有限。我们在北半球范围内的 48 个地点对海草（Zostera marina）群落中的常见猎物（活的端足类和腹足类）进行了捕食强度调查，涵盖了超过 37°的纬度和四个大陆海岸线。在所有海岸线上，随着纬度的增加，对端足类的捕食减少，但在温度梯度较大的西部海洋边缘减少得更为强烈。尽管实验时的原位水温与捕食没有相关性，但年平均温度强烈地正预测捕食，这表明这是一种比捕食时代谢活动增加更为复杂的机制。这种大规模的生物地理格局受到局部生境特征的影响；在各站点之间和内部，随着茎密度的增加，捕食减少。相比之下，腹足类的捕食率普遍较低，各站点之间变化不大。我们研究的高复制和地理范围不仅提供了更多支持捕食强度生物地理变化的证据，还深入了解了与温度和物种相互作用的生物地理梯度相关的机制。
