舟山群岛蝶类群落嵌套分布格局及其影响因素

片断化生境中群落的物种组成常呈现嵌套分布格局。2013年7-8月, 我们在浙江舟山群岛采用截线法对28个岛屿上的蝴蝶群落进行了野外调查, 探讨了岛屿物种嵌套分布格局及其影响因素。通过测量采集标本获得蝶类的生活史特征(最小需求面积、翅展和体重), 查阅文献资料获得蝶类的栖息地特征(岛屿面积、距最近大陆距离和距最近大岛距离), 分析了影响蝶类群落嵌套结构的因素。研究结果显示: (1)舟山群岛蝶类群落符合嵌套分布格局; (2)岛屿面积和物种最小需求面积对嵌套格局的形成有显著影响; (3)舟山群岛蝶类群落嵌套格局的形成支持选择性灭绝假说; (4)随机检验零模型结果显示该嵌套分布格局并非采样偏差造成的。因此, 在制定舟山群岛区域蝶类保护措施时, 应优先考虑那些分布在面积较大岛屿的和最小需求面积较大的物种。

Influencing factors of the nested distribution of butterfly assemblages in the Zhoushan Archipelago,China

In natural ecosystem, species assemblages in fragmented habitats frequently exhibit a nested subset pattern. Although nestedness has been documented for a wide range of taxa, it is rarely tested in butterfly assemblages in oceanic archipelago ecosystems. We surveyed the butterfly occupancy and abundance on 28 islands using a line-transect method in the Zhoushan Archipelago, China from July to August 2013. We determined island geographical factors (area, isolation) based on the literature and obtained species life-history traits (area requirement, wingspan and body weight) in the laboratory. The recently developed metric WNODF was used to examine the nestedness. Partial Spearman rank correlation was used to evaluate the associations of nestedness and island geographical factors as well as life-history traits related to species extinction and immigration tendencies. We found that the community composition of butterflies in the Zhoushan Archipelago was significantly nested. Island area and species’ area requirements were significantly correlated with nestedness after synthesis for all independent variables. In contrast, according to the null-model random test, nestedness of butterflies might not result from passive sampling or selective colonization. Our results indicate that selective extinction is the main driver of nestedness of butterflies in our system. From a conservation perspective, we suggest that large islands and species with large area requirements should be paid more attention in order to maximize the total number of species preserved.