Kishida Osamu, Costa Zacharia, Tezuka Ayumi, Michimae Hirofumi
Teshio Experimental Forest, Field Science Center for Northern Biosphere, Hokkaido University, Toikanbetsu, Horonobe, Hokkaido 098-2943, Japan.
Department of Biology, Virginia Commonwealth University, Richmond, VA, USA.
J Anim Ecol. 2014 Jul;83(4):899-906. doi: 10.1111/1365-2656.12186. Epub 2013 Dec 9.
Phenotypic plasticity can have strong impacts on predator-prey interactions. Although much work has examined the effects of inducible defences, less understood is how inducible offences in predators affect predator-prey interactions and predator and prey phenotypes. Here, we examine the impacts of an inducible offence on the interactions and life histories of a cohort of predatory Hynobius retardatus salamander larvae and their prey, Rana pirica tadpoles. We examined larval (duration, survival) and post-metamorphic (size) traits of both species after manipulating the presence/absence of tadpoles and salamanders with offensive (broadened gape width) or non-offensive phenotypes in pond enclosures. Offensive phenotype salamanders reduced tadpole survival and metamorph emergence by 58% compared to tadpole-only treatments, and by over 30% compared to non-offensive phenotypes. Average time to metamorphosis of frogs was delayed by 30% in the presence of salamanders, although this was independent of salamander phenotype. Thus, offensive phenotype salamanders reduced the number of tadpoles remaining in the pond over time by reducing tadpole survival, not by altering patterns of metamorph emergence. Offensive phenotypes also caused tadpoles to metamorphose 19% larger than no salamander treatments and 6% larger than non-offensive phenotype treatments. Pooled across salamander treatments, tadpoles caused salamanders to reach metamorphosis faster and larger. Moreover, in the presence of tadpoles, offensive phenotype salamanders metamorphosed 25% faster and 5% larger than non-offensive phenotype salamanders, but in their absence, neither their size nor larval period differed from non-offensive phenotype individuals. To our knowledge, this study is the first to demonstrate that inducible offences in predators can have strong impacts on predator and prey phenotypes across multiple life stages. Since early metamorphosis at a larger size has potential fitness advantages, the impacts of offensive phenotypes on frog and salamander life histories likely have significant consequences for individuals and populations. Furthermore, increased predation on tadpoles likely causes offensive phenotype individuals to have strong impacts on pond communities. Future studies should examine the fitness consequences of morphological and life-history plasticity across multiple life stages and should address the population and community level consequences of offensive phenotypes.
表型可塑性会对捕食者与猎物之间的相互作用产生强烈影响。尽管已有大量研究探讨了可诱导防御的影响，但对于捕食者的可诱导进攻如何影响捕食者与猎物之间的相互作用以及捕食者和猎物的表型，人们了解得较少。在这里，我们研究了一种可诱导进攻对一群捕食性东北小鲵蝾螈幼虫与其猎物日本林蛙蝌蚪之间的相互作用和生活史的影响。我们在池塘围栏中通过操纵蝌蚪和蝾螈的存在与否（具有进攻性（扩大口宽）或无进攻性表型），研究了这两个物种的幼虫（持续时间、存活率）和变态后（大小）特征。与仅存在蝌蚪的处理相比，具有进攻性表型的蝾螈使蝌蚪的存活率和变态出现率降低了58%，与无进攻性表型相比降低了30%以上。在有蝾螈存在的情况下，青蛙变态的平均时间延迟了30%，不过这与蝾螈的表型无关。因此，具有进攻性表型的蝾螈随着时间的推移通过降低蝌蚪的存活率而非改变变态出现模式，减少了池塘中剩余蝌蚪的数量。进攻性表型还使蝌蚪变态时比没有蝾螈处理的情况大19%，比无进攻性表型处理的情况大6%。综合蝾螈的处理情况来看，蝌蚪使蝾螈更快且更大地达到变态。此外，在有蝌蚪存在的情况下，具有进攻性表型的蝾螈比无进攻性表型的蝾螈变态快25%且大5%，但在没有蝌蚪的情况下，它们的大小和幼虫期与无进攻性表型个体没有差异。据我们所知，本研究首次证明捕食者的可诱导进攻会对多个生命阶段的捕食者和猎物表型产生强烈影响。由于在更大尺寸时提前变态具有潜在的适应性优势，进攻性表型对青蛙和蝾螈生活史的影响可能对个体和种群产生重大后果。此外，对蝌蚪的捕食增加可能导致具有进攻性表型的个体对池塘群落产生强烈影响。未来的研究应考察多个生命阶段形态和生活史可塑性的适应性后果，并应探讨进攻性表型在种群和群落水平上的后果。
