β diversity among ant communities on fragmented habitat islands: The roles of species trait, phylogeny and abundance

Yuhao Zhao and Xingfeng Si, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China, Nathan J. Sanders, Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, Juan Liu, Tinghao Jin, Haonan Zhou and Ping Ding, College of Life Sciences, Zhejiang University, Hangzhou, China, Ruisen Lu, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China

Background/Question/Methods
Habitat loss and fragmentation reduce biodiversity and alter species composition in local communities. β diversity describes the variation in species composition between or among communities in fragmented landscapes and has two components: species turnover and nestedness. In this study, we assessed β diversity of ant assemblages on 24 island fragments in the Thousand Island Lake, China. We constructed a species-level phylogenetic tree and measured five morphological traits of all ant species captured. We then assessed taxonomic (both incidence-based and abundance-weighted), functional, and phylogenetic β diversity and partitioned β diversity into turnover and nestedness (as well as the contributions of particular species and particular islands). Finally, we tested the relationships between β diversity and a suite of geographical variables (i.e., difference in island area, difference in isolation and inter-island distance) using Mantel tests.
Results/Conclusions
We found taxonomic and phylogenetic turnover components dominated overall β diversity whereas functional turnover and nestedness components contributed equally to overall β diversity. Overall β diversity increased with increasing differences in isolation and inter-island distance, however, only abundance-weighted overall β diversity decreased with increasing differences in island size. Our results indicated species that were abundant on large islands were also abundant on small islands. We conclude that dispersal limitation of ants shaped the β-diversity pattern along isolation and inter-island distance, and functional redundancy of species (i.e., different species share similar functional roles) could also explain β-diversity patterns on fragmented habitat islands. Our results highlight the necessity of incorporating both incidence-based and abundance-weighted community data when examining β diversity in fragmented landscapes. By partitioning β diversity into the contributions of particular species and particular fragments, our study demonstrates the important conservation values of small patches in maintaining biodiversity among ant communities.