Abstract：
Predators can strongly influence prey populations not only through consumptive effects (CE) but also through non-consumptive effects (NCE) imposed by predation risk. Yet, the impact of NCE on bioenergetic and stoichiometric body contents of prey, traits that are shaping life histories, population and food web dynamics, is largely unknown. Moreover, the degree to which NCE can evolve and can drive evolution in prey populations is rarely studied. A 6-week outdoor mesocosm experiment with Caged-Fish (NCE) and Free-Ranging-Fish (CE and NCE) treatments was conducted to quantify and compare the effects of CE and NCE on population densities, bioenergetic and stoichiometric body contents of Daphnia magna, a keystone species in freshwater ecosystems. We tested for evolution of CE and NCE by using experimental populations consisting of D. magna clones from two periods of a resurrected natural pond population: a pre-fish period without fish and a high-fish period with high predation pressure. Both Caged-Fish and Free-Ranging-Fish treatments decreased the body size and population densities, especially in Daphnia from the high-fish period. Only the Free-Ranging-Fish treatment affected bioenergetic variables, while both the Caged-Fish and Free-Ranging-Fish treatments shaped body stoichiometry. The effects of CE and NCE were different between both periods indicating their rapid evolution in the natural resurrected population. Both the Caged-Fish and Free-Ranging-Fish treatments changed the clonal frequencies of the experimental Daphnia populations of the pre-fish as well as the high-fish period, indicating that not only CE but also NCE induced clonal sorting, hence rapid evolution during the mesocosm experiment in both periods. Our results demonstrate that CE as well as NCE have the potential to change not only the body size and population density but also the bioenergetic and stoichiometric characteristics of prey populations. Moreover, we show that these responses not only evolved in the studied resurrected population, but that CE and NCE also caused differential rapid evolution in a time frame of 6 weeks (ca. four to six generations). As NCE can evolve as well as can drive evolution, they may play an important role in shaping eco-evolutionary dynamics in predator-prey interactions.
摘要：
捕食者不仅可以通过消耗效应（CE）而且可以通过捕食风险施加的非消耗效应（NCE）来强烈影响猎物种群。然而，NCE对猎物生物能和化学计量体含量的影响，塑造生活史的特征，人口和食物网动态，基本上是未知的。此外，很少研究NCE可以进化并可以推动猎物种群进化的程度。进行了为期6周的户外中观实验，采用笼鱼（NCE）和自由放养鱼（CE和NCE）处理，以量化和比较CE和NCE对种群密度的影响，大型蚤的生物能量和化学计量体含量，淡水生态系统中的基石物种。我们通过使用来自复活的自然池塘种群的两个时期的D.magna克隆组成的实验种群来测试CE和NCE的进化：没有鱼的鱼前期和具有高捕食压力的鱼高期。笼鱼和自由游鱼治疗都降低了体型和种群密度，尤其是高鱼时期的水蚤。只有Free-Ranging-Fish治疗会影响生物能量变量，而笼鱼和自由排列鱼的治疗方法都塑造了身体的化学计量。CE和NCE的影响在两个时期之间都不同，表明它们在自然复活种群中的快速进化。Caged-Fish和Free-Ranging-Fish处理都改变了前期鱼类和高鱼时期实验性水蚤种群的克隆频率，表明不仅CE而且NCE诱导克隆分选，因此，在这两个时期的中观实验期间，进化迅速。我们的结果表明，CE和NCE不仅有可能改变猎物种群的体型和种群密度，而且有可能改变猎物种群的生物能量和化学计量特征。此外，我们表明，这些反应不仅在研究的复活种群中进化，但是CE和NCE也在6周的时间范围内引起了差异快速进化（约四到六代)。由于NCE可以发展，也可以推动发展，它们可能在捕食者-猎物相互作用中形成生态进化动力学中起重要作用。
