Konrad Lorenz Institute for Ethology, Austrian Academy of Sciences, Savoyenstrasse 1A, Vienna, Austria.
J Evol Biol. 2011 May;24(5):1007-19. doi: 10.1111/j.1420-9101.2011.02233.x. Epub 2011 Feb 21.
While theoretical studies predict that inducible defences should be fine-tuned according to the qualities of the predator, very few studies have investigated how dangerousness of predators, i.e. the rate at which predators kill prey individuals, affects the strength of phenotypic responses and resulting benefits and costs of induced defences. We performed a comprehensive study on fitness consequences of predator-induced responses by involving four predators (leech, water scorpion, dragonfly larva and newt), evaluating costs and benefits of responses, testing differences in dangerousness between predators and measuring responses in several life history traits of prey. We raised Rana dalmatina tadpoles in the presence of free-ranging predators, in the presence of caged predators, and exposed naive and experienced tadpoles to free-ranging predators. Tadpoles adjusted the intensities of their behavioural and morphological defences to predator dangerousness. Survival was lower in the nonlethal presence of the most dangerous predator, while we could not detect costs of induced defences at or after metamorphosis. When exposed to free-ranging predators, small, but not large, tadpoles benefited from exhibiting an induced phenotype in terms of elevated survival when compared to naive tadpoles, but we did not observe higher survival either in tadpoles exhibiting more extreme phenotypes or in tadpoles exposed to the type of predator they were raised with. These results indicate that while predator-induced defences can mirror dangerousness of predators, costs and benefits do not necessarily scale to the magnitude of plastic responses.
虽然理论研究预测诱导防御应该根据捕食者的特征进行微调,但很少有研究调查捕食者的危险程度(即捕食者杀死猎物个体的速度)如何影响表型反应的强度以及诱导防御的收益和成本。我们通过涉及四种捕食者(水蛭、水蝎、蜻蜓幼虫和蝾螈)、评估反应的成本和收益、测试捕食者之间的危险程度差异以及测量猎物几个生活史特征的反应,对捕食者诱导反应的适应后果进行了全面研究。我们在自由生活的捕食者存在的情况下、在笼养捕食者存在的情况下以及在暴露于自由生活的捕食者的情况下,饲养了达尔马提亚蟾蜍蝌蚪。蝌蚪根据捕食者的危险程度调整其行为和形态防御的强度。在最危险的捕食者非致命存在的情况下,生存率较低,而在变态后或之后,我们无法检测到诱导防御的成本。当暴露于自由生活的捕食者时,与未暴露于捕食者的蝌蚪相比,表现出诱导表型的小而不是大的蝌蚪在生存率方面受益,但我们也没有观察到表现出更极端表型的蝌蚪或暴露于与饲养它们的捕食者相同类型的蝌蚪的生存率更高。这些结果表明,虽然捕食者诱导的防御可以反映捕食者的危险程度,但成本和收益不一定与塑性反应的幅度成比例。