AIMS: The importance of biotic interactions in creating and maintaining diversity is expected to increase towards low latitudes. However, the way in which predation affects diversity can depend on how predators mediate competitive interactions and also on defensive traits of prey. Here, we assessed the role of physical defences of prey to escape predation and how the importance of predation on community structure and diversity changes across latitude. LOCATION: Six sites, in three regions distributed across 45 degrees of latitude in the Atlantic Ocean: a tropical region in Angola, a subtropical region in Brazil and a temperate region in Wales, UK. METHODS: We manipulated predation on marine sessile communities, using exclusion cages and assessed community parameters, including their susceptibility to biological invasion during early and advanced succession. RESULTS: Predation was more intense in the tropics and in advanced communities suggesting that predation effects increase through time. In the tropical region, predators reduced the number of co‐occurring species and beta diversity, limited the occurrence of exotic species and promoted a change in the identity of the dominant organisms, replacing soft‐bodied organisms with calcified animals. In the subtropical region, predation promoted a similar trait‐mediated change in the identity of dominant prey, although it was not strong enough to affect diversity and did not prevent bioinvasion. In the temperate region, other processes than predation seem to drive the community organization and resistance to invasion. MAIN CONCLUSIONS: Our results support both Biotic Interaction and Biotic Resistance Hypotheses, showing that the importance of predation to biodiversity increases towards the tropics. In addition, where predation is intense, morphological traits of prey drive the final structure and dominance in the community. Our results suggest that physical defences are the main traits preventing predation, perhaps explaining why calcified organisms are among the most common invasive species in coastal habitats.

中文翻译：

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猎物的钙质防御结构介导了对热带的捕食和生物抗性的影响

目标：生物相互作用在创造和维持多样性方面的重要性预计将向低纬度地区增加。然而，捕食影响多样性的方式可能取决于捕食者如何调节竞争相互作用以及猎物的防御特征。在这里，我们评估了猎物物理防御在逃避捕食方面的作用，以及捕食对群落结构和多样性的重要性如何随纬度变化。位置：六个地点，分布在大西洋纬度 45 度的三个地区：安哥拉的热带地区、巴西的亚热带地区和英国威尔士的温带地区。方法：我们操纵捕食海洋固着群落，使用排除笼和评估群落参数，包括它们在早期和晚期演替过程中对生物入侵的敏感性。结果：捕食在热带地区和先进社区更为强烈，表明捕食效应会随着时间的推移而增加。在热带地区，捕食者减少了共生物种的数量和贝塔多样性，限制了外来物种的出现并促进了优势生物的身份变化，用钙化动物取代了软体生物。在亚热带地区，捕食促进了优势猎物身份的类似特征介导的变化，尽管它不足以影响多样性并且没有阻止生物入侵。在温带地区，捕食以外的其他过程似乎推动了社区组织和抵抗入侵。主要结论：我们的结果支持生物相互作用和生物抗性假设，表明捕食对生物多样性的重要性向热带地区增加。此外，在捕食激烈的地方，猎物的形态特征决定了群落中的最终结构和优势。我们的研究结果表明，物理防御是防止捕食的主要特征，这或许可以解释为什么钙化生物是沿海栖息地中最常见的入侵物种之一。