Gvoždík Lumír, Smolinský Radovan
Institute of Vertebrate Biology AS CR, Květná 8, CZ 60365, Brno, Czech Republic.
BMC Evol Biol. 2015 Nov 2;15:238. doi: 10.1186/s12862-015-0522-y.
Many animals rely on their escape performance during predator encounters. Because of its dependence on body size and temperature, escape velocity is fully characterized by three measures, absolute value, size-corrected value, and its response to temperature (thermal sensitivity). The primary target of the selection imposed by predators is poorly understood. We examined predator (dragonfly larva)-imposed selection on prey (newt larvae) body size and characteristics of escape velocity using replicated and controlled predation experiments under seminatural conditions. Specifically, because these species experience a wide range of temperatures throughout their larval phases, we predict that larvae achieving high swimming velocities across temperatures will have a selective advantage over more thermally sensitive individuals.
Nonzero selection differentials indicated that predators selected for prey body size and both absolute and size-corrected maximum swimming velocity. Comparison of selection differentials with control confirmed selection only on body size, i.e., dragonfly larvae preferably preyed on small newt larvae. Maximum swimming velocity and its thermal sensitivity showed low group repeatability, which contributed to non-detectable selection on both characteristics of escape performance.
In the newt-dragonfly larvae interaction, body size plays a more important role than maximum values and thermal sensitivity of swimming velocity during predator escape. This corroborates the general importance of body size in predator-prey interactions. The absence of an appropriate control in predation experiments may lead to potentially misleading conclusions about the primary target of predator-imposed selection. Insights from predation experiments contribute to our understanding of the link between performance and fitness, and further improve mechanistic models of predator-prey interactions and food web dynamics.
许多动物在遭遇捕食者时依赖其逃生能力。由于逃生速度取决于体型和温度，其完全由三个指标来表征，即绝对值、体型校正值及其对温度的响应（热敏感性）。捕食者施加选择的主要目标尚不清楚。我们在半自然条件下通过重复和受控的捕食实验，研究了捕食者（蜻蜓幼虫）对猎物（蝾螈幼虫）体型和逃生速度特征的选择。具体而言，由于这些物种在整个幼虫阶段经历广泛的温度范围，我们预测，在不同温度下都能达到高游泳速度的幼虫将比热敏感性更高的个体具有选择优势。
非零选择差异表明，捕食者对猎物体型以及绝对和体型校正后的最大游泳速度进行了选择。将选择差异与对照组进行比较证实，仅对体型存在选择，即蜻蜓幼虫更喜欢捕食小型蝾螈幼虫。最大游泳速度及其热敏感性显示出较低的群体重复性，这导致对逃生性能的两个特征均未检测到选择。
在蝾螈 - 蜻蜓幼虫的相互作用中，在捕食者捕食过程中，体型比游泳速度的最大值和热敏感性发挥更重要的作用。这证实了体型在捕食者 - 猎物相互作用中的普遍重要性。捕食实验中缺乏适当的对照可能会导致关于捕食者施加选择的主要目标得出潜在的误导性结论。捕食实验的见解有助于我们理解性能与适应性之间的联系，并进一步改进捕食者 - 猎物相互作用和食物网动态的机制模型。
