Spider Functional Trait Diversity is Not Correlated with Plant Functional Trait Diversity

Abstract

Ecological communities are subsets of larger-scale species pools. Community assembly may be due to ecological drift, resulting in communities with a random set of species and functional traits. However, ecological selection processes can act as filters and reduce functional trait diversity to a narrow subset, especially where environmental stress is high (aka trait clustering). Alternatively, ecological selection processes such as competition can require resource partitioning and thereby cause communities to have greater than expected functional trait diversity (aka trait overdispersion), especially where environmental stress is low. Trait-based community assembly may also be affected by scale. Environmental filtering should be most evident when comparing local communities to the largest spatial extent of the species pool and assembly should become increasingly random or overdispersed as the species pool extent is reduced in scale. We chose spiders because they are readily found in every terrestrial habitat and because they exhibit a high degree of functional diversity in body size, body shape, eyes, and mouthparts.