High correlation of species diversity patterns between specialist herbivorous insects and their specific hosts. (26th February 2020) - Du, Congcong
Abstract: Aim: The relative importance of biotic and abiotic factors in shaping the species diversity of temperate organisms has been debated for a long time. Here, we used drepanosiphine aphids as a model group to validate the 'resource‐dependent hypothesis' based on the biotic interactions for specialist herbivorous insects, a hypothesis stating that their intricate relationship with host plants for resources might constrain their species diversity from being positively correlated with the species diversity of their hosts, and to assess the role of biotic and abiotic factors in shaping the global species diversity pattern of temperate organisms. Location: Global and regional. Time period: Current. Taxon: Drepanosiphine aphids (Insecta: Hemiptera: Aphidoidea). Methods: We first investigated the global species diversity pattern of drepanosiphine aphids. Then we used ordinary least squares (OLS) and spatial simultaneous autoregressive (SAR) models to conduct regression analyses to test for the relationships of global and regional species richness between drepanosiphine aphids and their host plants, and other predictor variables describing entire woody plants, environmental energy, water availability, climate seasonality, topographical heterogeneity and land cover. Finally, structural equation models (SEMs) were further used to test for direct and indirect effects of key ecological variables. Results: The distribution hotspots of species richness and endemism were both located in temperate zones, supporting the notion that drepanosiphine aphids were representative of temperate organisms. The specific host plant was the most important ecological variable in explaining global and regional drepanosiphine species richness, showing a strong positive relationship. The climatic variables mainly showed an indirect effect on global and regional drepanosiphine species richness via specific hosts. Main Conclusions: The global and regional drepanosiphine species richness was primarily shaped by specific host plants as opposed to all woody trees, with indirect effects of climatic factors via host plants, which supported the 'resource‐dependent hypothesis' based on the biotic interactions for specialist herbivorous insects. This finding sheds new light on the 'biotic interactions hypothesis' that states biotic interactions can primarily affect the distributions and diversity patterns of both tropical and temperate organisms not only at the local scale but also at the regional to global scales.