Nested assemblages of aphid species in the Thousand Island Lake: The importance of island area and host plant diversity

Abstract

Aims: Nested subset pattern (nestedness) of species distributions is widespread in fragmented habitats. This study aims to explore the nested distribution pattern of aphid communities and the potential influencing mechanisms, including the effects of plant-aphid interaction and ant-aphid interaction on aphid community nesting structure, in the fragmented landscape of the Thousand Island Lake, China. Methods: We surveyed aphid communities on 18 land-bridge islands from May to August in both 2020 and 2021. Meanwhile, we surveyed host plant communities and mutualistic ant communities that have close interspecific interactions with aphid communities, along with integral plant communities in the aphid habitats. We analyzed the •研究报告• 华莱士诞辰200周年纪念专题蔡畅等: 千岛湖片段化生境中蚜虫群落嵌套格局的形成: 岛屿面积和寄主植物多样性的作用nestedness of the aphid communities and the integral plant communities by using NODF (nestedness metrics based on overlap and decreasing fill). We also used the random placement model to evaluate whether the passive sampling hypothesis played a major role in generating the nestedness of aphid communities. Moreover, we evaluated the role of island variables (island area and degree of isolation) in generating nestedness based on multiple linear regression. We also used the piecewise structural equation model to analyze the influence of island variables (island plant richness, host plant richness, and mutualistic ant richness) on the nestedness of aphid communities. Results:(1) Aphid assemblages were significantly nested in the Thousand Island Lake;(2) The nestedness of aphids was not caused by passive sampling;(3) The nestedness of aphid communities had a significantly positive correlation with island area in the Thousand Island Lake, which supports the hypothesis of selective extinction. The nestedness of integral plant communities also supports the hypothesis of habitat nestedness; (4) The piecewise structural equation models showed that the diversity of host plants had a significant and positive influence on the nested ranking of aphid assemblages. Conclusion:Our study showed that the nestedness of aphid communities in the Thousand Island Lake was driven by selective extinction and habitat nestedness, and the plant-aphid interaction, as an important intermediate factor, had a significantly direct effect on the nestedness. Therefore, the roles of interspecific interactions involving focus species should be fully considered when analyzing the underlying mechanism generating nested subset pattern.