Predator–prey interactions are a major driver of microbiome dynamics, but remain difficult to predict. While several prey traits potentially impact resistance to predation, their effects in a multispecies context remain unclear. Here, we leverage synthetic bacterial communities of varying complexity to identify traits driving palatability for nematodes, a main consumer of bacteria in soil. We assessed trophic interactions between four nematode species and 122 bacterial isolates, across a gradient of prey biodiversity ranging from single species to 50 species. Nematode size, a proxy for prey palatability, varied strongly with prey community composition and could be predicted by metabolic and morphological properties of the prey. However, the influence of prey traits on predators depended on biodiversity. Secondary metabolites drove palatability in monoculture, but this effect vanished under increasing prey biodiversity, where prey size became the dominant predictors of nematode size. Although idiosyncratic properties are often emphasized in the literatures, our results suggest that in biodiverse assemblages, the composition of available prey and their traits are more reliable predictors of predator–prey interactions. This study offers valuable insights into microbial ecology in the context of predator–prey interactions, as cryptic microbial responses can be guided by deductions based on generalizable biological traits.

中文翻译：

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限制捕食者生长的代谢物随着猎物的生物多样性而减弱


捕食者-猎物相互作用是微生物组动力学的主要驱动因素，但仍然难以预测。虽然几种猎物特征可能会影响对捕食的抵抗力，但它们在多物种背景下的影响仍不清楚。在这里，我们利用不同复杂性的合成细菌群落来确定驱动线虫适口性的特征，线虫是土壤中细菌的主要消费者。我们评估了四种线虫物种和 122 种细菌分离株之间的营养相互作用，猎物生物多样性的梯度从单个物种到 50 个物种不等。线虫大小是猎物适口性的代表，随猎物群落组成而有很大差异，可以通过猎物的代谢和形态特性来预测。然而，猎物特征对捕食者的影响取决于生物多样性。次生代谢物在单一栽培中推动了适口性，但这种影响在猎物生物多样性增加的情况下消失了，其中猎物大小成为线虫大小的主要预测因子。尽管文献中经常强调特殊特性，但我们的结果表明，在生物多样性组合中，可用猎物的组成及其特征是捕食者-猎物相互作用的更可靠预测指标。这项研究为捕食者-猎物相互作用背景下的微生物生态学提供了有价值的见解，因为隐蔽的微生物反应可以通过基于可推广的生物学特征的推论来指导。