枝角类多样化反捕食防御策略的调节机制及其对气候变化与水体富营养化双重作用的响应

The anti-predation defense strategy of prey plays an important role in preventing severe fluctuation of different trophic levels in the food chain. Cladocerans are important component of zooplankton in freshwater ecosystem, and it has highly diversified defense strategies in the face of different predators, but its mechanism, as a basic scientific issue, is still not systematically solved. Under the dual effects of climate change and water eutrophication, the multiple anti-predation defense strategies of cladocerans may be affected directly or indirectly, which may impact the stability of the population dynamics of both the predator and the prey. Therefore, the regulation mechanism of multiple anti-predation defense strategies in cladocerans and its response to the dual stress of climate change and water eutrophication are not only a basic science issue deserved to explore but also an potential environmental and ecological problem which urgently need to be paid attention. This project will carry out the following studies: the trade-off and cost of multiple defense strategies in cladocerans against predation; the effects of different defense strategies on the population dynamics of their own and the upper and lower trophic level; determining the location of the predator kairomone; separating and identifying the kairomones from different predators; the organ and the process of Daphnia to detect different kairomones; the molecular mechanisms of regulating multiple anti-predation defense strategies in cladocerans; the impacts of secondary products caused by climate change and eutrophication (such as changes in kaironmone degrading rate, food composition and quality, and water physicochemical index etc.) on the anti-predation defense strategies in cladocerans; the adaptive evolution of cladocera defense strategies to long-term climate change and eutrophication.

猎物针对捕食作用采取的防御策略，对防止食物链不同营养级种群剧烈波动起着重要作用。枝角类是浮游动物的重要组成部分，对不同捕食者表现出高度多样化的防御策略，其形成机制还是尚未系统解决的基础科学问题。在气候变化与水体富营养化双重作用下，枝角类多样化防御策略将受到直接或间接的影响，进而可能影响到种群动态的稳定。因此，枝角类多样化防御策略的调节机制以及对气候变化和水体富营养化双重作用的响应，不仅是一个值得深入探讨的基础科学问题，也是一个迫切需要关注的潜在环境生态问题。本项目将开展以下研究：枝角类多样化防御策略的权衡与代价以及对上下营养级种群动态的影响；捕食者信息素的产生部位与分离鉴定；枝角类对捕食者信息素感知过程；枝角类防御策略调节的分子机制；气候变化与富营养化导致的次生变化（如信息素衰减速率、食物质量、水体理化指标等）对枝角类防御策略的冲击；枝角类防御策略对气候变化和富营养化的长期适应性进化。

猎物针对捕食作用采取的防御行为，对防止食物链不同营养级种群的剧烈波动、维持生态系统结构和功能的稳定发挥重要作用。枝角类对不同捕食者表现出高度多样化的防御策略，其机制还是尚未系统解决的基础科学问题。另外，气候变化与水体富营养化不仅直接影响水生生物的代谢、生活史、种群动态，还干扰物种间的正常防御行为，进而影响到食物链的稳定。基于上述科学问题，本项目展开了系统的研究，取得了以下主要结果：.（1）针对我国水域生态系统中常见枝角类及其捕食者，揭示了优势枝角类诱导型防御特征表达模式、可逆性及关键调控通路的分子机制，建立了完善有效的研究模型；.（2）揭示了枝角类的诱导型防御策略具有一定的环境成本，竞争和资源限制会对其诱导型防御策略造成多样化的干扰效应；.（3）阐明了枝角类诱导型防御的母体效应，揭示了枝角类反捕食防御特征变化与种群动态的耦联效应，确认了捕食者信息素对枝角类有性生殖的影响；.（4）发现了捕食者和猎物身份在信息素产生中的作用，揭示了枝角类识别的信息素类型的多样性并具有趋同演化趋势，确认捕食风险信号形成的物质基础，阐明了作为信息素降解者的浮游细菌对枝角类诱导型防御存在的影响；.（5）发现了视觉系统在枝角类响应捕食和感知捕食风险信号中的作用重要作用，阐明了无光和人工光干扰会造成枝角类无法准确评估光照依赖的捕食风险；.（6）证明了在不同捕食风险和不同环境压力下，枝角类偏向于形成具有捕食者或环境特异性的响应通路，从而缓解了枝角类响应复杂捕食风险环境的困境；.（7）系统地阐释了气候变化与富营养化可以通过食物、温度和环境胁迫等多种途径干扰到枝角类对捕食者的快速响应，并分析了具体环境因子下猎物反捕食防御策略的变化趋势；.（8）结合野外和长期实验室模拟研究，揭示了枝角类诱导型防御与其生存环境和关键通路上的基因变异具有高度的相关性，且环境胁迫和气候变化均会削弱枝角类诱导型防御的表达能力。.上述结果对于多层次全面深刻理解枝角类多样化防御策略和推动诱导型防御理论发展具有重要理论意义，对于预测在气候变化与富营养化下水域生态系统种间关系的演变趋势以及维护健康的水域生态系统结构和功能也具有重要的现实指导意义。