Death‐feigning behaviours increase survival rate of littoral cladocerans under predation by odonate larvae
Death‐feigning behaviours increase survival rate of littoral cladocerans under predation by odonate larvae
复制标题
假死行为提高了滨海枝角类动物在圆齿幼虫捕食下的存活率
DOI：
10.1111/fwb.13808
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发表时间：
2021
影响因子：
2.7
通讯作者：
Jotaro Urabe
中科院分区：
文献类型：
--
作者：
Sayumi Yamada;Jotaro Urabe
由于沿岸的枝角类是齿形幼体的常见猎物，它们是研究水生生境中猎物和捕食者相互作用的理想生物。虽然在沿岸的枝角类中观察到的假死行为被认为是降低捕食风险的一种特征，但没有研究探讨假死在降低死亡率方面的有效性。我们研究了两种沿岸的枝角类，球腔壶菌和细尾尖尾壶菌，对频率合瓣藻有齿幼虫的假死行为的有效性。我们首先研究了有齿幼虫如何发现猎物，发现幼虫即使在黑暗条件下也会吃掉活跃的枝角类，但它们不吃麻醉的枝角类，这表明，幼虫通过机械线索（如猎物个体产生的振动电流）来探测猎物。然后，我们使用视频记录系统观察了牙形幼虫和猎物枝角类动物的行为事件，在有齿幼体攻击时表现出假死行为的枝角类动物数量，以及在表现出假死行为时没有被吃掉的枝角类动物数量。我们在捕食者-捕食者相互作用中共观察到1，099个行为事件。平均而言，牙形虫幼虫追捕63%的枝角类动物，攻击89%的被追捕枝角类动物，第一次攻击仅成功捕获29%的枝角类动物。在未被捕获的枝角类动物中，38%的个体继续游泳，但62%的个体停止移动并表现出假死行为。实验结果表明，具有假死行为的枝角类对有齿类幼虫的捕获率明显低于持续游动的枝角类，表明沿岸的枝角类的假死行为有效地降低了有齿类幼虫的捕食率。这些结果表明，假死作为一种适应性行为，以减少死亡风险的沿岸的枝角类捕食下，这样的捕食者，可以检测到猎物使用机械线索，如振动电流。
Because littoral cladocerans are common prey for odonate larvae, they are ideal organisms to examine prey and predator interactions in aquatic habitats. Although death‐feigning behaviour observed in littoral cladocerans is viewed as a trait to reduce predation risk, no study has examined the effectiveness of death‐feigning at reducing mortality. We studied the effectiveness of death‐feigning behaviour by two littoral cladocerans,Chydorus sphaericusandOxyurella tenuicaudis, against the odonate larvae ofSympetrum frequens.We first examined how the odonate larvae detected the prey and found that the larvae consumed active cladocerans, even under dark conditions, but they did not consume anaesthetised cladocerans, indicating that the larvae detect the prey using mechanical cues such as vibrational currents created by the prey individuals.We then observed behavioural events of odonate larvae and prey cladocerans using a video‐recording system to count the number of cladocerans that showed death‐feigning behaviours when odonate larvae attacked and those that were not consumed when they showed death‐feigning behaviours.We observed a total of 1,099 behavioural events in prey–predator interactions. On average, the odonate larvae pursued 63% of the cladocerans encountered, attacked 89% of the cladocerans pursued, and successfully captured only 29% of the cladocerans with the first attack. Among the cladocerans that were not captured, 38% of the individuals continually swam, but 62% ceased to move and exhibited death‐feigning behaviours. The odonate larvae's capture rate for cladocerans exhibiting the death‐feigning behaviours fell significantly short of that for cladocerans that were continually swimming.The experiments clearly showed that the littoral cladocerans' death‐feigning behaviour effectively decreased predation rate by odonate larvae. The results suggest that the death feigning serves as an adaptive behaviour to reduce mortality risk in littoral cladocerans under predation by such predators that can detect prey using mechanical cues such as those of vibrational currents.