Growth, developmental, and size structure responses of tadpole prey under increasing threats from newts
Growth, developmental, and size structure responses of tadpole prey under increasing threats from newts
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在蝾螈威胁日益增加的情况下蝌蚪猎物的生长、发育和体型结构反应
DOI：
10.1139/cjz-2019-0067
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
and A. Mori
中科院分区：
文献类型：
--
作者：
Ramamonjisoa N.;and A. Mori
群体内的大小变异对群落生态学和进化有着深远的影响。虽然对资源的竞争通常会增加大小的变化，（非消费性）捕食对这一人口特征的影响仍然相对知之甚少。现有的模型表明，增长率（介导的资源水平）和表达的大小变异（变异系数测量）在猎物队列之间的正相关关系。我们测试了这种预测，通过暴露蝌蚪的日本森林绿色树蛙（Rhacophorus arboreus（冈田和川野，1924年）=Zhangixalus arboreus（冈田和川野，1924年））的非致命存在的缺口有限的日本火腹蝾螈（Cynops pyrrhogaster（Boie，1826年））在低和高捕食者密度在室外围隔实验。蝌蚪的生长速率和附着生物的生物量增加蝾螈密度。但与预测相反，增长率的提高并没有增加，但相反，降低了蝌蚪的群体大小变异性。我们讨论了这一结果背后的两个潜在机制。首先，增加资源的可用性介导的捕食者喂养可能会减少竞争的力量，最终导致更均匀地分配资源收益的个人之间;第二，如果较小的个人增长相对较快，比较大的个人，以加快进入一个大小避难所对缺口有限的捕食者，那么个体间的大小差异可能会随着时间的推移而减少。
Size variability within a cohort can have profound effects on community ecology and evolution. Although competition for resources generally increases size variability, the effect of (non-consumptive) predation on this demographic trait remains relatively poorly understood. Existing models suggest a positive correlation between growth rate (mediated by resource level) and expression of size variability (as measured by the coefficient of variation) in prey cohorts. We tested this prediction by exposing the tadpoles of the Japanese Forest Green Treefrog (Rhacophorus arboreus(Okada and Kawano, 1924) =Zhangixalus arboreus(Okada and Kawano, 1924)) to the non-lethal presence of gape-limited Japanese Fire-bellied Newts (Cynops pyrrhogaster(Boie, 1826)) at low and high predator densities in an outdoor mesocosm experiment. Tadpole growth rates and periphyton biomass increased with newt density. But in contrast to prediction, elevated growth rates did not increase but, reversely, decreased cohort size variability in the tadpoles. We discuss two potential mechanisms behind this outcome. First, increased resource availability mediated by predator feeding may have reduced the strength of competition, ultimately leading to more evenly distributed resource gains among individuals; second, if smaller individuals grew relatively faster than larger individuals, as to quicken entry to a size refuge against the gape-limited predator, then inter-individual size differences could diminish over time.