Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada.
Department of Veterinary Biomedical Science, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK, S7N 5B4, Canada.
Sci Rep. 2017 Feb 23;7:43255. doi: 10.1038/srep43255.
Through time, the activity patterns, morphology, and development of both predators and prey change, which in turn alter the relative vulnerability of prey to their coexisting predators. Recognizing these changes can thus allow prey to make optimal decisions by projecting risk trends into the future. We used tadpoles (Lithobates sylvaticus) to test the hypothesis that tadpoles can extrapolate information about predation risk from past information. We exposed tadpoles to an odour that represented either a temporally consistent risk or an increasing risk. When tested for their response to the odour, the initial antipredator behaviour of tadpoles did not differ, appearing to approach the limit of their maximum response, but exposure to increasing risk induced longer retention of these responses. When repeating the experiment using lower risk levels, heightened responses occurred for tadpoles exposed to increasing risk, and the strongest responses were exhibited by those that received an abrupt increase compared to a steady increase. Our results indicate that tadpoles can assess risk trends through time and adjust their antipredator responses in a way consistent with an extrapolated trend. This is a sophisticated method for prey to avoid threats that are becoming more (or less) dangerous over part of their lifespan.
随着时间的推移，捕食者和猎物的活动模式、形态和发育都会发生变化，这反过来又改变了猎物相对于其共存捕食者的相对脆弱性。因此，认识到这些变化可以使猎物通过将风险趋势投射到未来来做出最佳决策。我们使用蝌蚪（Lithobates sylvaticus）来检验一个假设，即蝌蚪可以从过去的信息中推断出捕食风险的信息。我们将蝌蚪暴露在一种气味中，该气味代表了时间上一致的风险或不断增加的风险。当测试它们对气味的反应时，蝌蚪最初的防御行为并没有差异，似乎接近其最大反应的极限，但暴露于不断增加的风险会导致这些反应的持续时间更长。当使用较低的风险水平重复实验时，暴露于不断增加的风险的蝌蚪会产生更高的反应，而与逐渐增加相比，突然增加的蝌蚪会表现出最强的反应。我们的结果表明，蝌蚪可以通过时间评估风险趋势，并以与推断趋势一致的方式调整它们的防御反应。这是一种复杂的方法，用于避免在其生命周期的一部分中变得更（或更少）危险的威胁。
