Scaling-up effects of intra-specific phenotypic polymorphism on lake ecosystems : experimental approaches

在湖泊生态系统中，藻类和鱼类分别被视为初级生产者和顶级捕食者，我们利用微观世界和中观实验系统测试了它们的表型可塑性或多态如何影响食物网和生态系统属性。利用转录组和QTL分析等分子技术，阐明了鱼类营养多态(浮游-底栖种对)是受多基因变异控制的，具有较小的加性效应，不同种对的系统发育具有相同的游泳性能相关基因的表达模式，提示鱼类对远洋环境的适应具有趋同进化的可能性。我们还通过实验证明，鱼类营养多态不仅改变了食物链长度、捕食者-捕食者质量比和群落平均营养水平等食物链属性，而且还通过营养级联效应改变了群落呼吸作为生态系统的功能。利用理论模型，我们最终证实了表型可塑性或多态特征的进化在食物网络结构和稳定性方面具有生态后果。

We tested how phenotypic plasticity or polymorphism of algae and fish, which are regarded as primary producers and top-predators in lake ecosystems, respectively, can affect food web and ecosystem properties, using microcosm and mesocosm experimental systems. Taking the advantage of molecular technique, such as transcriptome and QTL analyses, we elucidated that fish trophic polymorphism(planktivory-benthivory species pair) is under the control of polygenic variation in a large number of loci with small additive effects and found that the expression pattern of swimming performance-related genes is shared among different phylogenies with species pair, suggesting the possibility of convergent evolution of adaptation to pelagic environments. We also experimentally demonstrated that fish trophic polymorphism altered not only food web properties, such as food chain length, prey-predator mass ratio and community-average trophic level, but also community respiration as ecosystem functioning through trophic cascading effects. Using theoretical models, we finally corroborated that the evolution of phenotypically plastic or polymorphic traits have ecosystem consequences in terms of food web configuration and stability.