Department of Biology, Western Washington University, Bellingham, WA 98225, USA.
Oecologia. 2010 May;163(1):69-78. doi: 10.1007/s00442-010-1570-z. Epub 2010 Feb 12.
Predator-induced hatching plasticity has been demonstrated in many species of amphibians. However, animals from other clades (e.g., marine species of molluscs and annelids) also place their embryos in capsules or gelatinous masses and might also exhibit hatching plasticity to predators. To date there is no evidence of predator-induced hatching plasticity from any marine species or a major clade of bilateria animals, the Lophotrochozoa. We studied predator-induced hatching plasticity of Nucella lamellosa, a carnivorous marine snail that deposits embryos in capsules. We used two experiments to investigate the effects of two types of predator, crabs and isopods, on developing embryos. In the first experiment, we quantified proportion of hatched embryos from capsules through time exposed to water-borne chemicals of crabs and isopods. Crabs delayed time-to-hatching, and the effects of predators were additive. In the second experiment, we quantified proportion of hatched embryos from capsules through time, developmental stage, and size of embryos in capsules exposed to water-borne chemicals of crabs and conspecifics. With this experiment, we wanted to answer: (1) whether a delay in hatching corresponded to embryos developing slower, and (2) whether the general products of metabolic waste from organisms can delay hatching. We unexpectedly observed that adult conspecific snails accelerated hatching but not developmental rate-the few past studies on the effects of conspecifics have all demonstrated that conspecifics delay time-to-hatching and rate of development. The results were also inconsistent with metabolic waste in general causing a delay in hatching, although the effect of conspecifics does weaken this inference. This study demonstrates that predators delay time-to-hatching in a marine mollusc, and suggests that predator-induced hatching plasticity is widespread among animals and likely evolved multiple times within the bilateria. In addition, conspecifics accelerated time-to-hatching in a marine mollusc, which suggests that conspecifics, like predators, might commonly influence when embryos hatch.
捕食者诱导的孵化可塑性已在许多两栖动物物种中得到证实。然而，其他进化枝（例如，海洋软体动物和环节动物）的动物也将其胚胎放置在胶囊或凝胶状物质中，并且也可能对捕食者表现出孵化可塑性。迄今为止，尚无来自任何海洋物种或两侧动物的主要进化枝 Lophotrochozoa 的捕食者诱导孵化可塑性的证据。我们研究了肉食性海洋蜗牛 Nucella lamellosa 的捕食者诱导孵化可塑性，该蜗牛将胚胎沉积在胶囊中。我们使用两个实验来研究两种类型的捕食者（螃蟹和等足类动物）对发育中胚胎的影响。在第一个实验中，我们通过随时间暴露于螃蟹和等足类动物的水载化学物质来量化从胶囊中孵化的胚胎的比例。螃蟹延迟了孵化时间，并且捕食者的影响是累加的。在第二个实验中，我们通过随时间，发育阶段和胶囊中胚胎的大小来量化从胶囊中孵化的胚胎的比例，将螃蟹和同种的水载化学物质暴露于胶囊中。通过这个实验，我们想回答：（1）孵化延迟是否对应于胚胎发育较慢，以及（2）生物体的代谢废物的一般产物是否可以延迟孵化。我们出人意料地观察到，同种成年蜗牛加速了孵化，但没有加速发育速度-过去关于同种动物影响的少数研究都表明，同种动物会延迟孵化时间和发育速度。结果也与代谢废物通常导致孵化延迟的说法不一致，尽管同种动物的作用确实削弱了这种推断。这项研究表明，捕食者会延迟海洋软体动物的孵化时间，并表明捕食者诱导的孵化可塑性在动物中广泛存在，并且可能在两侧动物中多次进化。此外，同种动物加速了海洋软体动物的孵化时间，这表明同种动物与捕食者一样，可能通常会影响胚胎的孵化时间。
