Scale-dependent contribution of biotic and abiotic factors to longhorn beetles (Cerambycidae) community composition variation at the Indo- Burma biodiversity hotspot

Abstract

Despite centuries of exploration, our perception of potential mechanisms determining the species community assemblage is still in infancy . Longhorn beetle as an insect with larval stage feeds on the xylem of plants or trees, the relative importance of biotic (host-specificity) and abiotic (climate gradients) processes to determining their community compositional variation is unknown. In the aim of exploring the knot, we therefore designed the experiment throughout multiple spatial scales (macro/regional and micro/local) along tropical to temperate climate gradients at the Indo-Burma biodiversity hotspot, to examine to what extent biotic and abiotic factors may exert a significant influence on longhorn beetle species composition assembly, and whether this relationship is scale dependent. The relationships between longhorn beetles species composition variation and biotic and abiotic factors were examined using β-dissimilarity indices comparison，NMDS analysis , variation partitioning based on RDA, linear mixed-effect model and mantel test. We found a positive relationship between the species compositional variation of both beetle and plants, in which longhorn beetle species dissimilarity apparently track changes in plant dissimilarity both at macro/regional and micro/local scales. NMDS analysis showed that abiotic factors have prominent influence to the longhorn beetle community assemblage. Variation partitioning and linear mixed-effect model retained significantly correlated Environment and plant diversity metrics for beetle diversity. Thus, we concluded that: 1) biotic and abiotic factors collaboratively shaped longhorn beetle community composition along various spatial scales; 2) the relative importance of abiotic and biotic variation explaining the longhorn beetle community composition vary by spatial scale; and 3) biotic interactions have prominent effect to longhorn beetle community composition at local-scale while macroclimatic gradients impose the most control on it at macro-scale. Besides, our study showed that the influence of dispersal limitation in the species assembly of longhorn beetles from tropical to temperate area was minor compared with plant communiti