植物与传粉者合作的进化动态研究

Explaining the evolution of cooperation is one of central problems for evolutionary ecology. The cooperation between plants and their pollinators could develop through the exchange of rewards and services, which could be as the idea model for the evolution of cooperation. The plant-pollinator mutualism is beset by two fundamental challenges that arise due to information asymmetry (the quality of a potential partner is known only to itself): 1) how to choose a good partner before the interaction is established; 2) how to prevent an individual from exploiting the resources of plants. For the former, the problem can be solved by signalling game: The plants could signal their reward quality or quantity, and the pollinators could use the plants’ signals to determine whether or not to visit the plants. A central topic in plant-pollinator signalling game is how the honest signalling can be maintained when there are interest conflicts between plants and pollinators. For the latter, evolutionary game theory and theories of species coexistence provide the framework to solve the problem. The interactions between plants with the different defensive strategies and floral visits (pollinator and nectar robber) could be as a two-population game. The of maintenance of cooperation could be best understood based on evolutionary dynamics of the game. In some situations, the stable coexistence of cooperators and cheaters could be helpful to maintain the cooperation between plants and pollinators..In this study, we focus on four questions: 1) how could honest signalling be maintained and what are evolutionarily stable strategies in plant-pollinator siganlling game 2) could resource limitation in reward and signal production and/or the foraging strategies of pollinators contribute to the maintenance of honest signalling in Salvia przewalskii, Delphinium caerulem and Aconitum gymnandrum by evaluating the signal-reward correlation in natural populations; 3) how do the evolutionary dynamics of the two-population game in the plant (defensive or non-defensive)-pollinator (pollinating or nectar robbing) interaction associated with simulated robbing experiments in field; 4) could pollinators and nectar robbers be stable coexistence in the field. These results would help to identify key mechanisms related to plant-pollinator cooperation. Under the framework of evolution of cooperation, this work by linking evolutionary game theory analysis and field experiments would provide insights into the evolutionary dynamics of cooperation between the species.

合作的进化是进化生态学中的中心问题之一。植物与传粉者通过“报酬换服务”方式形成的合作，是研究物种间合作进化的理想系统。由于双方信息不对称，植物与传粉者合作进化面临两个核心问题：1)如何选择合作伙伴建立合作关系；2)如何阻止欺骗策略以维持合作。本项目针对上述核心问题，通过使用进化博弈论和物种共存理论，并结合对甘西鼠尾草、翠雀和露蕊乌头的野外实验以阐明植物与传粉者合作的建立与维持机制及其进化动态。研究内容包括：1)建立植物-传粉者信号博弈分析诚实信号作为进化稳定策略的条件；2)资源限制和传粉者觅食策略对植物诚实信号的作用；3)建立植物(防御或不防御盗蜜)-传粉者(传粉或盗蜜)的二种群博弈模型结合人工操控盗蜜实验分析物种间合作的进化动态及其稳定性；4)传粉者和盗蜜者的共存对植物-传粉者合作维持的作用。本项目通过理论分析与实验检验有机的结合，研究结果将深化对物种间合作进化的理解。

植物与传粉者合作关系的建立与维持面临着两个挑战性的问题: 1)由于植物报酬质量是隐藏特征，当植物通过发送与报酬相关的诚实信号吸引传粉者建立合作关系时，这一诚实信号是如何被维持；2)双方建立合作关系后，面对欺骗者，这一合作关系是如何被维持。本项目围绕这两个核心问题，展开进化博弈模型和传粉实验的研究工作。本项目取得重要的研究结果包括：1)通过对已有代价信号博弈模型和Pygmalion博弈模型假定的扩展，提出更为一般化的分析信号诚实性的理论框架。分析结果表明多种潜在的机制可维持植物的诚实信号，其中包括，植物个体质量与信号强度间的异速关系；植物信号生产的代价与成功发送信号的概率；传粉者觅食策略对信号的进化响应；传粉者与高质量植物个体发送者相遇的概率。2)通过建立和分析传粉者吸引博弈，从理论上证明植物可通过受亲缘选择所支持的最优资源分配策略以合作吸引传粉者；模型明确给出植物合作吸引传粉者的条件和理论预期，也为植物应对传粉危机提供可行的机制。3)通过对翠雀属(Delphinium)和乌头属(Aconitum)物种花性状间相关性分析并结合其传粉类群特征表明，传粉者觅食策略可能维持信号的诚实性。4)基于物种共存理论探讨植物-传粉者合作关系的维持。通过物种间相互作用动态与复制动态的结合，对植物与传粉者二种群间博弈进行分析。结果表明，合作和欺骗物种可通过周期振荡的方式共存于合作系统中。二者共存的关键因素是报酬的生产代价与欺骗者的效率。这一研究结果将合作进化动态与种间互作理论相联系，有助于识别促进合作维持与解体的关键因素。根据多种策略可在传粉合作系统中共存，提出一个基于石头-布-剪刀博弈分析进化稳定策略多态性的方法。同时，通过野外传粉调查和物种鉴定，获取群落水平植物与其传粉昆虫物种组成的关键数据，并提出基于传粉网络结构特征度量传粉生态位的方法。上述的研究结果、关键数据和方法理解种间合作进化的动态提供新的视角，也为通过维持传粉合作关系以保护生物多样性提供支撑。