Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, USA.
Department of Entomology, University of Wisconsin-Madison, Madison, WI, USA.
Mol Ecol. 2021 Feb;30(3):855-873. doi: 10.1111/mec.15769. Epub 2020 Dec 28.
Although most predators are generalists, the majority of studies on the association between prey availability and prey consumption have focused on specialist predators. To investigate the role of highly generalist predators in a complex food web, we measured the relationships between prey consumption and prey availability in two common arthropodivorous bats. Specifically, we used high-throughput amplicon sequencing coupled with a known mock community to characterize seasonal changes in little brown and big brown bat diets. We then linked spatiotemporal variation in prey consumption with quantitative prey availability estimated from intensive prey community sampling. We found that although quantitative prey availability fluctuated substantially over space and time, the most commonly consumed prey items were consistently detected in bat diets independently of their respective abundance. Positive relationships between prey abundance and probability of consumption were found only among prey groups that were less frequently detected in bat diets. While the probability of prey consumption was largely unrelated to abundance, the community structure of prey detected in bat diets was influenced by the local or regional abundance of prey. Observed patterns suggest that while little brown and big brown bats maintain preferences for particular prey independently of quantitative prey availability, total dietary composition may reflect some degree of opportunistic foraging. Overall, our findings suggest that generalist predators can display strong prey preferences that persist despite quantitative changes in prey availability.
尽管大多数捕食者都是杂食性的，但大多数关于猎物丰度与猎物消耗之间关系的研究都集中在专门的捕食者上。为了研究高度杂食性捕食者在复杂食物网中的作用，我们测量了两种常见的食虫蝙蝠中猎物消耗与猎物丰度之间的关系。具体来说，我们使用高通量扩增子测序结合已知模拟群落来描述小棕蝠和大棕蝠饮食的季节性变化。然后，我们将猎物消耗的时空变化与从密集的猎物群落采样中估计的定量猎物丰度联系起来。我们发现，尽管定量猎物丰度在空间和时间上有很大的波动，但在蝙蝠饮食中，最常消耗的猎物种类独立于其各自的丰度而始终被检测到。仅在在蝙蝠饮食中较少检测到的猎物群体中，发现了猎物丰度与消耗概率之间的正相关关系。虽然猎物消耗的概率与丰度基本无关，但在蝙蝠饮食中检测到的猎物群落结构受到猎物本地或区域丰度的影响。观察到的模式表明，尽管小棕蝠和大棕蝠保持对特定猎物的偏好，而不受定量猎物丰度的影响，但总饮食组成可能反映出一定程度的机会性觅食。总的来说，我们的研究结果表明，尽管猎物的定量供应发生变化，但一般捕食者可以表现出强烈的猎物偏好。
