Intraspecific trait variation has large effects on the ecosystem and is greatly affected by human activities. To date, most studies focused on single-trait analyses, while considering multiple traits is expected to better predict how an individual interacts with its environment. Here, we used a mesocosm experiment with fish Oryzias latipes to test whether individual growth, boldness and functional traits (feeding rate and stoichiometric traits) formed one functional pace-of-life syndrome (POLS). We then tested the effects of among-individual mean and variance of fish functional POLSs within mesocosms on invertebrate community (e.g. zoobenthos and zooplankton abundances) and ecosystem processes (e.g. ecosystem metabolism, algae stock, nutrient concentrations). Stoichiometric traits correlated with somatic growth and behaviours, forming two independent functional POLS (i.e. two major covariance axes). Mean values of the first syndrome were sex- and environment-dependent and were associated with (i) long-term (10 generations; 4 years) selection for small or large body size resulting in contrasting life histories and (ii) short-term (6 weeks) effects of experimental treatments on resource availability (through manipulation of light intensity and interspecific competition). Specifically, females and individuals from populations selected for a small body size presented fast functional POLS with faster growth rate, higher carbon body content and lower boldness. Individuals exposed to low resources (low light and high competition) displayed a slow functional POLS. Higher mesocosm mean and variance values in the second functional POLS (i.e. high feeding rate, high carbon:nitrogen body ratio, low ammonium excretion rate) were associated to decreased prey abundances, but did not affect any of the ecosystem processes. We highlighted the presence of functional multi-trait covariation in medaka, which were affected by sex, long-term selection history and short-term environmental conditions, that ultimately had cascading ecological consequences. We stressed the need for applying this approach to better predict ecosystem response to anthropogenic global changes.

中文翻译：

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日本青鳉、Oryzias latipes 多性状响应环境变化的生态系统后果


种内性状变异对生态系统影响较大，受人类活动影响较大。迄今为止，大多数研究都集中在单一特征分析上，同时考虑多个特征有望更好地预测个体如何与其环境相互作用。在这里，我们使用Oryzias latipes鱼进行了中生态实验，以测试个体生长、胆量和功能性状（摄食率和化学计量性状）是否形成一种功能性生活节奏综合症（POLS）。然后，我们测试了中生态系统内鱼类功能 POLS 的个体间均值和方差对无脊椎动物群落（例如底栖动物和浮游动物丰度）和生态系统过程（例如生态系统代谢、藻类储量、营养浓度）的影响。化学计量特征与体细胞生长和行为相关，形成两个独立的功能 POLS（即两个主要协方差轴）。第一种综合征的平均值取决于性别和环境，并且与以下因素相关：(i) 长期（10代；4年）对小体型或大体型的选择，导致不同的生活史；(ii) 短期（10代；4年）选择6 周）实验处理对资源可用性的影响（通过操纵光强度和种间竞争）。具体来说，来自体型较小的群体的女性和个体表现出快速功能性 POLS，具有更快的生长速度、更高的碳体含量和更低的胆量。暴露于低资源（低光照和高竞争）的个体表现出缓慢的功能性 POLS。第二个函数 POLS 中更高的介观均值和方差值（即 高摄食率、高碳氮比、低铵排泄率）与猎物丰度下降有关，但不影响任何生态系统过程。我们强调了青鳉中存在功能性多性状共变，这种共变受到性别、长期选择历史和短期环境条件的影响，最终产生了级联的生态后果。我们强调需要应用这种方法来更好地预测生态系统对人为全球变化的反应。