基于拓扑网络的浙江南部近海群落关键种识别及其调控机制研究

Keystone species are a group of biological species that play a decisive role in community stability and species diversity. In recent years, they have attracted the attention of ecologists and have become one of the research hotspots in the field of ecology. The biodiversity in China coastal seas has decreased drastically, and once the keystone species disappear, it will lead to other types of extinction or resource changes, which will lead to greater impacts on community or ecological ecosystem structure. Therefore, identifying keystone species of these communities and evaluating their regulatory mechanisms on ecological communities will play a vital role in biological protection. This project aims to accurately and quantitatively describe the nutritional relationship between community organisms by using stomach content analysis and stable isotope techniques in the high-nutrient species from the offshore waters of southern Zhejiang. And, based on this, the topological structure of food web is constructed. Then, using topological network indices combined with KPP calculation to identifying and verification the keystone species of the community, and analyzes the up-and-down control mechanisms of the keystone species in the food web. Furthermore，focuses on simulating keystone species loss, the topological indices are used to investigate the effects of species removal on the number of trophic species and the robustness of the food web. The results of this project will strengthen our understanding of the importance of keystone species in the community, and provide guidelines for the development of China's offshore biodiversity conservation policy-making and the research of structure and function of an ecosystem.

关键种(Keystone species)是对群落稳定性和物种多样性起决定作用的一类生物类群，近年来备受生态学家关注，已成为生态学领域的研究热点之一。我国近海生物多样性急剧减小，而一旦关键种消失，将导致其他种类的灭绝或资源上的巨变，最终引发群落或生态结构发生较大变化，因此识别群落关键种，摸清其对生态群落的调控机制将对生物保护起至关重要作用。本项目拟以浙江南部近海中高营养层次种类为对象，运用胃含物分析和稳定同位素技术准确定量描述群落生物间的营养关系，并基于此构建食物网拓扑结构，以拓扑网络指标结合KPP运算识别验证群落关键种，分析关键种在食物网中的上下行控制机制；以关键种为模拟移除对象，参照拓扑学指标分析物种移除对其他物种丰度的影响并评价食物网的稳健性。本项目的研究结果将加深我们对群落关键种重要性的认识，为今后我国近海生物多样性保护政策制定及生态系统结构和功能研究提供理论依。

关键种(Keystone species)是对群落稳定性和物种多样性起决定作用的一类生物类群。我国近海生物多样性急剧减小，而一旦关键种消失，可能引发群落或生态结构发生较大变化。本项目选取浙江南部近海为研究区域，运用胃含物分析和稳定同位素技术量化分析海域内生物群落营养结构特征，并分析重要鱼类种间营养相互作用；构建食物网拓扑结构，通过拓扑指数、物种排序以及模拟移除等手段识别和解析关键种在食物网结构中的调控作用。结果显示：浙江南部近海海洋生物群落同位素比值跨度范围较大，食源多样性和营养多样性较高；食性类型包括杂食性、底栖动物食性、浮游动物食性、混合食性和游泳动物食性，除底栖食性和浮游食性摄食存在显著差异外，其他食性类群都具有一定的摄食重叠，且多数鱼类食性存在随个体发育和季节的转变，这种转变有助于减小种内和种间竞争，提高物种共存和维持群落结构稳定性；重要鱼类带鱼相比其他鱼类具有更宽的营养生态位宽幅，表现出强烈的占有食物资源及利用资源的能力，而大黄鱼相比其他鱼类营养生态位宽幅较小，对资源的占有能力相对较弱，与具有相似营养位置的鱼种间重叠剧烈，在食源竞争中处于劣势地位；计算11种拓扑关键性参数结合KPP运算筛选鱼类群落结构关键种，筛选出带鱼和七星底灯鱼在鱼类群落结构的稳定性中起关键作用，其中带鱼为关键捕食者，七星底灯鱼为关键被捕食者；对10个食物网拓扑关键指数进行主成分分析，确定海鳗、细螯虾、带鱼、口虾蛄、细条天竺鲷为食物网中排位前五的关键种，模拟去除物种发现排位越靠前的物种在去除后对整体结构指数的影响越大，其中带鱼被去除后食物网整体结构的变化程度最大，海鳗在被模拟去除后是使得其他物种中心性变化最大的物种，这些物种的丧失将会导致食物网结构稳定性下降。研究结果有助于加深我们对海洋生物间复杂的营养相互作用、群落关键种和调控重要性的认识，为今后我国近海生物多样性保护政策制定及生态系统结构和功能研究提供理论依据。