Department of Genetics and Genome Biology, University of Leicester, United Kingdom.
Department of Mathematics, University of Leicester, United Kingdom.
PLoS One. 2022 Mar 14;17(3):e0264996. doi: 10.1371/journal.pone.0264996. eCollection 2022.
Quantifying feeding behaviour of generalist predators at the population and individual levels is crucial for understanding the structure and functioning of food webs. Individual predator/consumer feeding niches can be significantly narrower than that of the population across animal taxa. In such species, the population of a generalist predator becomes essentially an ensemble of specialist individuals and this often highly affects the dynamics of the prey-predator interactions. Currently, few experimental systems exist that are both easily technically manipulated in a lab and are reliable to accurately assess effects of individual specialisation within generalist predators. Here we argue that a freshwater predaceous snail, Anentome helena (also known as an 'assassin snail'), is a convenient and reliable experimental system to study feeding of a generalist predator on multiple food types which exhibits well-pronounced specialisation of foraging individuals. Using A. helena we experimentally test: (i) how relative prey abundances in the environment affect the feeding patterns, (ii) whether the feeding patterns are consistent over the duration of the experimental period, and (iii) compare the feeding niche breadth of individuals to that of the laboratory population. By offering four different prey snail species, at a range of relative abundances, we show that there are consistent patterns in feeding. Importantly, the consumption of each prey was independent of the relative abundance at which they were present. Individual predators showed selectivity to a particular prey, i.e. the population of assassin snails seems to be formed of individuals that specialise on different prey. Our findings would contribute to the recent revision and the ongoing debate on the classification of predator species into generalists and specialists.
量化广食性捕食者在种群和个体水平上的摄食行为对于理解食物网的结构和功能至关重要。在动物分类群中，个体捕食者/消费者的取食生态位可能明显窄于种群的取食生态位。在这种物种中，广食性捕食者的种群实际上成为了专门个体的集合，这通常会极大地影响猎物-捕食者相互作用的动态。目前，很少有实验系统既易于在实验室中进行技术操作，又能可靠地准确评估广食性捕食者个体专门化的影响。在这里，我们认为淡水捕食性蜗牛 Anentome helena（也称为“刺客蜗牛”）是一个方便可靠的实验系统，可以研究广食性捕食者对多种食物类型的摄食行为，这些食物类型表现出明显的觅食个体专业化。我们使用 A. helena 实验测试：（i）环境中相对猎物丰度如何影响摄食模式，（ii）摄食模式是否在实验期间保持一致，以及（iii）将个体的取食生态位宽度与实验室种群进行比较。通过提供四种不同的猎物蜗牛物种，在一系列相对丰度下，我们发现摄食模式具有一致性。重要的是，每种猎物的消耗与它们存在的相对丰度无关。个体捕食者对特定的猎物表现出选择性，即刺客蜗牛的种群似乎由专门捕食不同猎物的个体组成。我们的研究结果将有助于最近对捕食者物种分类为广食性和专门性的修订和正在进行的辩论。
