亚热带破碎化森林种实昆虫与其寄主植物种间互作多样性研究

A challenge in ecology has been to study the spatial dynamics of species interactions and food webs, and how global environment changes affect species interactions and food web persistence. The topic is central to biodiversity losses from habitat fragmentation/change and understanding ecological responses to global environment change. We believe that a potential solution to both the problem of studying global changes such as habitat fragmentation lies in turning attention directly to species interactions identified as network motifs, and to seek understanding from a greater number of dimensions of biodiversity. Based on our previous long-term works about pairwise interactions from fruit/seed-feeding insects and their host plants in the Dujiangyan subtropical forest, our proposal will use DNA barcoding for identification, network motifs for species interactions, and computer modeling, to address how forest fragmentation and succession affect different dimensions of diversity such as interaction diversity, species/phylogenetic diverstiy and functional diversity, and to understand how these diversity dimensions response to the global change drivers.The methodologies developed are likely to guide future investigations of species interactions and food webs. This project will be fruitful for better understanding the mechanims related to plant-animal co-evolution and biodiversity, and will also provide basical knowledge and recommendation for biodiversity conservation, management and sustainability of forest resources.

目前生态学领域最具挑战性的科学问题是如何揭示物种间相互作用和食物网的空间动态。回答这一问题对于理解生境变化所导致的生物多样性丧失以及生物多样性丧失所造成的生态后果极为重要。研究生境破碎化等全球变化问题既可对作为网络单元的物种间相互作用进行研究，还可通过生物多样性的不同维度来进行研究。本项目拟以都江堰亚热带森林种实昆虫与其寄主植物为研究系统，采用DNA分类、网络分析和模型模拟等先进方法来探讨种间互作、谱系和功能性状等生物多样性维度之间的内在联系及其对生境破碎化和森林演替的响应机制，揭示全球环境变化对生物多样性和食物网的影响。总体上，本项目将提出了一种新的方法来探讨在生境破碎化背景下物种间相互作用与食物网稳定性的维持机制，研究结果将为动植物协同进化理论、生物多样性维持机制、生物多样性保护管理评价以及森林资源可持续利用提供基础资料和科学依据。

本项目取得了以下主要研究结果：（1）在昆虫目水平上发现亲缘关系近的物种倾向于与同目的昆虫发生互作，且植物系统发育信号的产生和果实类型相关。在物种水平，发现干果植物和种实昆虫互作网络中存在较强的系统发育信号，说明亲缘关系较近的干果植物物种倾向于与同种昆虫发生互作。（2）证实网络结构在植物-种实昆虫互作网络和植物-食果动物互作网络中存在较大差异：植物-种实昆虫互作网络的特化水平和嵌套性要小于种子-食果动物互作网络，而其模块性高于种子-食果动物互作网络。通过随机模拟群落植物灭绝，表明植物丧失对种实昆虫的影响要高于食果动物。（3）使用同质园和生物地理的比较研究，明确了在本土昆虫对种子的危害上，引入种栎树小于本土栎树和其原厂地，而且“天敌逃逸”与亲缘关系有关，即当引入种的亲缘关系与本土物种较近时，其虫蛀率与本土物种相比不显著；而当引入种的亲缘关系与本土物种较远时，其虫蛀率要显著低于本土物种。（4）发现种实昆虫对种子大小的选择存在较强时间依赖性，剪枝象和象虫属均倾向于选择特定大小的种子进行产卵。研究结果为动植物协同进化理论、生物多样性维持机制、生物多样性保护管理评价以及评估生物入侵机制和风险提供科学依据。