Seasonal shifts in predator body size diversity and trophic interactions in size-structured predator-prey systems
Seasonal shifts in predator body size diversity and trophic interactions in size-structured predator-prey systems
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DOI：
10.1111/j.1365-2656.2011.01935.x
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发表时间：
2012-05-01
影响因子：
4.8
通讯作者：
Rudolf, Volker H. W.
中科院分区：
文献类型：
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作者：
Rudolf, Volker H. W.
1. 理论表明，捕食者多样性和猎物抑制之间的关系应该取决于捕食者特征的变化，如体型，这强烈影响物种相互作用的类型和强度。被捕食的物种经常面对各种不同大小的捕食者，捕食者的体型组成在群落之间和群落内部会随着季节的变化而变化。在这里，我测试了捕食者群落大小结构的变化如何影响猎物的生存，使用食人种群大小结构的季节性变化作为模型系统。实验室和野外实验表明，尽管捕食者与被捕食者的体型比越高，人均食用量越高，但食肉动物的平均体型越大，死亡率就越低。相反，猎物的死亡率在捕食者体型多样性的最高水平上达到顶峰。此外，观察到的猎物死亡率显著高于假设捕食者大小类别之间没有间接相互作用的零模型的预测，表明不同大小的捕食者不是可替代的，而是具有加性效应。更高的捕食者体型多样性因此增加了猎物的死亡率，尽管在额外的实验室实验中，捕食者之间的行为干扰和捕食行为的可能性增加了。因此，捕食者体型分布的季节变化不仅通过捕食者平均体型的变化，还通过捕食者体型分布的变化改变了对猎物的抑制强度。总的来说，这表明单个性状（即体型）内的变化（即多样性）可以影响营养相互作用的强度，并强调了天然食物网尺寸结构的季节性变化对群落动态的重要性。
1. Theory suggests that the relationship between predator diversity and prey suppression should depend on variation in predator traits such as body size, which strongly influences the type and strength of species interactions. Prey species often face a range of different sized predators, and the composition of body sizes of predators can vary between communities and within communities across seasons.2. Here, I test how variation in size structure of predator communities influences prey survival using seasonal changes in the size structure of a cannibalistic population as a model system. Laboratory and field experiments showed that although the per-capita consumption rates increased at higher predator-prey size ratios, mortality rates did not consistently increase with average size of cannibalistic predators. Instead, prey mortality peaked at the highest level of predator body size diversity.3. Furthermore, observed prey mortality was significantly higher than predictions from the null model that assumed no indirect interactions between predator size classes, indicating that different sized predators were not substitutable but had more than additive effects. Higher predator body size diversity therefore increased prey mortality, despite the increased potential for behavioural interference and predation among predators demonstrated in additional laboratory experiments.4. Thus, seasonal changes in the distribution of predator body sizes altered the strength of prey suppression not only through changes in mean predator size but also through changes in the size distribution of predators. In general, this indicates that variation (i.e. diversity) within a single trait, body size, can influence the strength of trophic interactions and emphasizes the importance of seasonal shifts in size structure of natural food webs for community dynamics.