Predation risk suppresses the positive feedback between size structure and cannibalism
Predation risk suppresses the positive feedback between size structure and cannibalism
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DOI：
10.1111/j.1365-2656.2011.01871.x
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发表时间：
2011-11-01
影响因子：
4.8
通讯作者：
Nishimura, Kinya
中科院分区：
文献类型：
--
作者：
Kishida, Osamu;Trussell, Geoffrey C.;Nishimura, Kinya
1.同类相食可以在生态群落的结构和动态中发挥重要作用。以往的研究强调了大小结构和密度的同类相食的物种在塑造短期和长期的同类相食动态的重要性，但我们的理解捕食者如何影响同类相食动态是有限的。这是尽管广泛的证据表明，许多猎物物种表现出行为和形态的适应性，以应对捕食风险。本研究探讨了黑黄Aeshna nigroflava幼虫捕食风险的存在和不存在如何影响其猎物小鲵幼虫的同类相食动态。我们发现，大小结构和同类相食之间的反馈动力学依赖于是否存在捕食风险。在缺乏风险线索，蝾螈大小结构和食人之间的正反馈，通过时间发生，因为在这个治疗中的大多数复制品包含至少一个蝾螈幼虫具有扩大的张口（即食人）。相反，这种反馈和同类相食的出现很少被观察到存在的风险线索。一旦蝾螈大小的分歧发生，实验逆转的存在或不存在的风险线索并没有改变现有的同类相食的动态作为实验的进展。因此，风险对驱动食人动态的机制的影响可能在蝾螈幼虫的早期发育期间起作用。捕食风险的影响可能会禁止启动的大小结构和同类相食之间的动态之间的相互作用的行为方面孵化。我们的捕食试验清楚地表明，遇到率之间的孵化和预期的食人族的预期猎物的咬和摄食率显着较低的存在与不存在的捕食风险，即使食人族和受害者之间的大小不对称是类似的风险治疗。这些结果表明，饥饿风险线索首先抑制孵化的同类相食，然后防止大小变化随着时间的推移而增加。我们认为，大小结构和同类相食之间的正反馈动态和捕食风险的修改也可能在其他系统中运行，以塑造同类相食的猎物物种的种群动态以及整体社区动态。
1. Cannibalism can play a prominent role in the structuring and dynamics of ecological communities. Previous studies have emphasized the importance of size structure and density of cannibalistic species in shaping short- and long-term cannibalism dynamics, but our understanding of how predators influence cannibalism dynamics is limited. This is despite widespread evidence that many prey species exhibit behavioural and morphological adaptations in response to predation risk.2. This study examined how the presence and absence of predation risk from larval dragonflies Aeshna nigroflava affected cannibalism dynamics in its prey larval salamanders Hynobius retardatus.3. We found that feedback dynamics between size structure and cannibalism depended on whether dragonfly predation risk was present. In the absence of dragonfly risk cues, a positive feedback between salamander size structure and cannibalism through time occurred because most of the replicates in this treatment contained at least one salamander larvae having an enlarged gape (i.e. cannibal). In contrast, this feedback and the emergence of cannibalism were rarely observed in the presence of the dragonfly risk cues. Once salamander size divergence occurred, experimental reversals of the presence or absence of dragonfly risk cues did not alter existing cannibalism dynamics as the experiment progressed. Thus, the effects of risk on the mechanisms driving cannibalism dynamics likely operated during the early developmental period of the salamander larvae.4. The effects of dragonfly predation risk on behavioural aspects of cannibalistic interactions among hatchlings may prohibit the initiation of dynamics between size structure and cannibalism. Our predation trials clearly showed that encounter rates among hatchlings and biting and ingestion rates of prospective prey by prospective cannibals were significantly lower in the presence vs. absence of dragonfly predation risk even though the size asymmetry between cannibals and victims was similar in both risk treatments. These results suggest that dragonfly risk cues first suppress cannibalism among hatchlings and then prevent size variation from increasing through time.5. We suggest that the positive feedback dynamics between size structure and cannibalism and their modification by predation risk may also operate in other systems to shape the population dynamics of cannibalistic prey species as well as overall community dynamics.