Touchon Justin C, Wojdak Jeremy M
Department of Biology, Boston University, Boston, Massachusetts, United States of America; Smithsonian Tropical Research Institute, Balboa, República de Panamá
Department of Biology, Radford University, Radford, Virginia, United States of America.
PLoS One. 2014 Jun 26;9(6):e100623. doi: 10.1371/journal.pone.0100623. eCollection 2014.
Many animals respond to predation risk by altering their morphology, behavior, or life-history. We know a great deal about the cues prey respond to and the changes to prey that can be induced by predation risk, but less is known about how plastic responses to predators may be affected by separate plastic responses occurring earlier in life, particularly during the embryonic period. Embryos of a broad array of taxa can respond to egg- or larval-stage risks by altering hatching timing, which may alter the way organisms respond to future predators. Using the red-eyed treefrog (Agalychnis callidryas), a model for understanding the effects of plasticity across life-stages, we assessed how the combined effects of induced variation in the timing of embryo hatching and variation in the larval predator community impacted tadpole morphology, pigmentation and swimming performance. We found that A. callidryas tadpoles developed deeper tail muscles and fins and darker pigmentation in response to fish predators, either when alone or in diverse community with other predators. Tadpoles altered morphology much less so to dragonfly naiads or water bugs. Interestingly, morphological responses to predators were also affected by induced differences in hatching age, with early and late-hatched tadpoles exhibiting different allometric relationships between tail height and body length in different predator environments. Beyond induced morphological changes, fish predators often damaged tadpoles' tails without killing them (i.e., sublethal predation), but these tadpoles swam equally quickly to those with fully intact tails. This was due to the fact that tadpoles with more damaged tails increased tail beats to achieve equal swimming speed. This study demonstrates that plastic phenotypic responses to predation risk can be influenced by a complex combination of responses to both the embryo and larval environments, but also that prey performance can be highly resilient to sublethal predation.
许多动物通过改变其形态、行为或生活史来应对捕食风险。我们对猎物所响应的线索以及捕食风险可能引发的猎物变化了解很多，但对于对捕食者的可塑性反应如何受到生命早期（尤其是胚胎期）发生的单独可塑性反应的影响却知之甚少。众多分类群的胚胎可以通过改变孵化时间来应对卵期或幼虫期的风险，这可能会改变生物体对未来捕食者的反应方式。利用红眼树蛙（红眼睛树蛙）这一用于理解跨生命阶段可塑性影响的模型，我们评估了胚胎孵化时间的诱导变化和幼虫捕食者群落变化的综合影响如何影响蝌蚪的形态、色素沉着和游泳性能。我们发现，无论是单独存在还是与其他捕食者共同存在于多样化群落中，红眼睛树蛙蝌蚪都会因鱼类捕食者而发育出更深的尾肌和鳍以及更暗的色素沉着。蝌蚪对豆娘幼虫或水蝽的形态改变要小得多。有趣的是，对捕食者的形态反应也受到孵化年龄诱导差异的影响，早期和晚期孵化的蝌蚪在不同的捕食者环境中，尾高与体长之间呈现出不同的异速生长关系。除了诱导的形态变化外，鱼类捕食者经常会在不杀死蝌蚪的情况下损伤它们的尾巴（即亚致死捕食），但这些蝌蚪游泳速度与尾巴完全完整的蝌蚪一样快。这是因为尾巴受损更严重的蝌蚪会增加尾部摆动次数以达到相同的游泳速度。这项研究表明，对捕食风险的可塑性表型反应可能受到对胚胎和幼虫环境反应的复杂组合的影响，而且猎物的表现对亚致死捕食具有高度的恢复力。
