石栎属两种果实类型对不同捕食压力的适应机制分析

壳斗科石栎属植物的果实形态极为多样，这与其物种的适应性进化和分布格局密切相关。申请人前期研究发现，石栎属两种果实类型存在形态和物理化学防御的权衡，推测它们可能代表不同捕食压力下出现的两种适应性对策：1）花托包被实的高物理防御限制昆虫捕食，同时促进脊椎动物对其进行散播，大且营养丰富的种子有利于萌发定植；2）橡实果皮机械防御弱，更易被捕食，但其单个果实小，果实总产量大，因此足够数量的种子可躲避捕食，完成萌发。本申请项目拟在横断山脉地区，选取两类果实共生的样点，收集果实并利用显微CT分析果实和虫蛀状态，结合散播追踪实验，解析石栎属两种果实类型与其食果动物的互作机制；阐明两种果实类型存在的理化权衡是否是不同捕食压力下的产物，在石栎属的适应性进化中有何作用。本研究可解析代表两种果实类型的石栎物种同域共存的机制，为横断山脉地区常绿阔叶林生态系统的保护和管理提供重要指导。

The great fruit morphological diversity of Lithocarpus is closely associated with the adaptive evolution and species distribution of the genus. Previously, we have discovered that there was fruit morphological differentiation as well as seed chemical and mechanical trade-off between the two major fruit types of Lithocarpus. We hypothesize that these two fruit types could represent two adaptive mechanisms under different predation pressure: 1) the higher mechanical defense of enclosed receptacle fruits restricts the insect predation and promotes their seed dispersal by vertebrates, and the bigger and more nutritious seeds support germination and seedling survival; 2) Whereas acorn fruits with lower physical protection have high predation rate, but their smaller fruit size indicates bigger total fruit production, which is the key to escape predation and complete seed germination. We propose to select the sample sites with species representing both fruit types in the Hengduan Mountains region, and examine the interactions among the fruits of Lithocarpus and their animal predators, by micro-CT scanning the fruits combining with seed dispersal experiments. Based on the experimental results, we will test whether the differentiation in fruit morphology, seed chemistry and physical defenses between the two fruit types are results of the varied predation pressures from insects and vertebrates, and their function in shaping the adaptive strategies of Lithocarpus. This study will reveal the co-existing mechanisms of two fruit types of Lithocarpus, which would be essential guidance for biodiversity and ecosystem conservation and forest management in the evergreen forests of the Hengduan Mountains in the future.