Laurila Anssi, Pakkasmaa Susanna, Crochet Pierre-André, Merilä Juha
Department of Population Biology, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden.
Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden.
Oecologia. 2002 Aug;132(4):524-530. doi: 10.1007/s00442-002-0984-7. Epub 2002 Aug 1.
Predation pressure during early life stages is often high, but few studies have examined antipredator responses at these stages. We studied the effects of an egg predator (leech, Haemopis sanguisuga) and two tadpole predators (dragonfly larvae, Aeshna spp.; and threespine stickleback, Gasterosteus aculeatus) on the timing of hatching and morphology of hatchlings and young tadpoles in two anuran amphibians [Rana arvalis (RA) and R. temporaria (RT)] in a factorial laboratory experiment. We also compared the responses of two geographically separated RA populations on the Baltic island of Gotland and in Uppland on the Swedish mainland. We found inconsistent evidence for the predictions that the presence of an egg predator induces earlier hatching, and the presence of a larval predator delays hatching. RT hatched later in the presence of stickleback than in the control treatment, but RA hatched earlier, less developed and at smaller size in the leech, dragonfly, and stickleback treatments. There was no indication of predator-induced morphology in hatchlings of either of the species. However, young RA tadpoles had shorter tails and deeper bodies in the stickleback treatment and RT had shorter tails in the leech, dragonfly and stickleback treatments. Irrespective of treatment, RA from Gotland hatched with relatively longer bodies than Uppland individuals and had relatively deeper and short tails as young tadpoles. Our results highlight the diversity of induced responses to predators in anuran amphibians: predator presence affects the timing of hatching and morphology of young tadpoles, but these responses vary depending on the species and predator considered.
在生命早期阶段，捕食压力通常很高，但很少有研究考察这些阶段的反捕食者反应。我们在一项析因实验室实验中，研究了一种卵捕食者（水蛭，血红蛭）和两种蝌蚪捕食者（蜻蜓幼虫，艾氏属；三刺鱼，刺鱼）对两种无尾两栖动物（林蛙和欧洲林蛙）孵化时间以及孵化幼体和幼蝌蚪形态的影响。我们还比较了波罗的海哥特兰岛和瑞典大陆乌普萨拉两个地理隔离的林蛙种群的反应。对于卵捕食者的存在会诱导提前孵化以及幼虫捕食者的存在会延迟孵化这两个预测，我们发现的证据并不一致。在有三刺鱼存在的情况下，欧洲林蛙的孵化时间比对照处理晚，但林蛙在有水蛭、蜻蜓和三刺鱼的处理中孵化得更早，发育程度更低且体型更小。两种物种的孵化幼体均未显示出捕食者诱导的形态变化。然而，在三刺鱼处理中，林蛙幼蝌蚪的尾巴较短且身体更深，在水蛭、蜻蜓和三刺鱼处理中，欧洲林蛙幼蝌蚪的尾巴较短。无论处理方式如何，来自哥特兰岛的林蛙孵化时身体相对较长，作为幼蝌蚪时尾巴相对更深且更短。我们的结果凸显了无尾两栖动物对捕食者诱导反应的多样性：捕食者的存在会影响幼蝌蚪的孵化时间和形态，但这些反应因所考虑的物种和捕食者而异。
