Factors underlying bird community assembly in anthropogenic habitats depend on the biome

Abstract

Production activities drive the replacement of original habitats with artificial ones, leading to new bird assemblages. In this study, we assessed if anthropogenic habitats acted as environmental filters causing functional redundancy or as promoters of functional divergence, depending on the biome. We also investigated if functional patterns derived from phylogenetic convergence or clustering. For this purpose, we computed the standardized effect sizes (SES) for avian functional and phylogenetic diversity using null models and compared the SES values among tree plantations, urban settlements (US), cattle pastures (CP), crop fields (CF) and natural habitats from two biomes: grassland and forest. We used generalized least squares models to test if functional and phylogenetic SES indicated functional redundancy or divergence, and phylogenetic convergence or clustering. We found functional redundancy in grassland and functional divergence in forest associated with environmental filtering and competitive exclusion, respectively. In grassland, functional structure was not associated with a clear phylogenetic pattern, while in forest functional divergence was caused by evolutionary convergence in CF and CP and conservation in US. The prevalences of functional redundancy and functional divergence patterns and their associated predominant mechanism of community assembly were found to depend on the biome and the regional species pool.