千岛湖兽类群落嵌套格局及其影响机制研究

The nested subset pattern or nestedness is one of the most important research issues in the subjects of island biogeography and community ecology. However, several new and important problems in this research field, such as the roles of detection probability, phylogeny and species abundance in generating nested subset patterns, have rarely been investigated so far. The program will use the Thousand Island Lake as the research platform and use mammals as the target taxon to investigate these unsolved scientific questions in the nested subset pattern. The program aims to determine the processes and mechanisms underlying the nested subset pattern in the mammal assemblages in the Thousand Island Lake. To achieve the goal, we will test several important hypotheses such as passive sampling hypothesis, selective extinction hypothesis, selective colonization hypothesis and habitat nestedness hypothesis. By testing these hypotheses, we will first examine the roles of detection probability, phylogeny and species abundance in generating the nested subset patterns, then determine the life-history differences in nested species and idiosyncratic species, and finally determine the main factors and mechanisms influencing the nested subset pattern of mammal assemblages in the Thousand Island Lake. The program is important to the theoretical development of the subjects of island biogeography, community ecology and conservation biology. The program is also helpful for understanding the effects of the construction of dams on mammal biodiversity and community composition, establishing effective conservation strategies on biodiversity, and providing strong basis to the evaluation of ecological impacts of other similar dam projects.

嵌套格局是岛屿生物地理学和群落生态学的重要前沿研究领域和核心问题之一。但是，在该研究领域中，有关发现率、系统发育、物种多度在嵌套格局形成中所起的作用等新出现的重要国际前沿课题，现有研究还未有涉及。为解决上述问题，本项目将以千岛湖人工湖泊陆桥岛屿为研究平台，以兽类为研究对象，以被动取样假说、选择性灭绝假说、选择性迁移假说、栖息地嵌套假说等重要理论假说为基础，深入分析发现率、系统发育、物种多度在嵌套格局形成中的作用，并进一步探讨嵌套物种与特异性物种的生活史特征差异；通过检验各种与嵌套格局相关的理论假说，确定影响千岛湖兽类群落组成的主要因素及其形成机理。该项目的实施，不仅对丰富与发展岛屿生物地理学、群落生态学和保护生物学等相关理论具有重要意义，而且对深入了解水库大坝建设后兽类多样性和群落组成的变化，提出相应的保护对策等方面具有重要参考价值，还将为今后类似水库大坝项目的生态影响评价提供科学依据。

本项目以千岛湖人工湖泊陆桥岛屿为研究平台，以兽类为研究对象，对其嵌套格局及影响因素进行了深入研究。本项目主要取得了以下一些重要研究结果：（1）千岛湖地区共有大中型兽类14种，隶属于7目11科，其中穿山甲和黑麂是我国一级重点保护动物，豹猫和毛冠鹿是我国二级重点保护动物，猪獾被世界自然保护联盟IUCN列为易危物种。（2）千岛湖地区共有小型兽类12种，隶属于2目2科，包括食虫目鼩鼱科2种和啮齿目鼠科10种，其中社鼠是该地区的优势种。（3）千岛湖大中型兽类在物种水平上呈现出明显的嵌套分布格局。分析表明，岛屿面积和物种的最小面积需求是影响嵌套格局的主要因素。因此，千岛湖大中型兽类的嵌套格局符合选择性灭绝假说。（4）千岛湖大中型兽类在功能和谱系上也呈现出明显的嵌套分布格局。分析表明，岛屿面积、距最近大岛的距离和生境多样性是影响大中型兽类功能嵌套和谱系嵌套的主要因素。（5）千岛湖大中型兽类明显存在小岛屿效应，其面积阈值为2.56公顷。千岛湖大中型兽类小岛屿效应的形成可能与随机事件、偶然干扰或营养补给等因素有关。（6）千岛湖小型兽类的体型大小在栖息地片段化和隔离后60年后就发生了明显改变。与大陆种群相比，岛屿社鼠种群的体重和体长均明显增大；而且与7个大岛相比，13个小岛上社鼠的体重和体长也显著增大。岛屿上社鼠种群体型变大主要是由于岛屿上猛禽、蛇类、肉食目兽类的捕食者物种数减少所引起的。以上研究成果对于丰富与发展岛屿生物地理学、群落生态学、生活史理论及保护生物学等相关理论具有重要意义；对于深入了解水库大坝建设对兽类多样性的影响，提出相应的保护对策等方面也具有重要参考价值。