Plants with higher dispersal capabilities follow 'abundant-centre' distributions but such patterns remain rare in animals

Abstract

The ‘abundant-centre’ hypothesis posits that a species’ abundance is highest at its range centre and declines towards its range edge. Recently, the hypothesis has been much debated, with supporting empirical evidence remaining limited. Here, we test the hypothesis on 3660 species using 5,703,589 abundance observations. We summarise species-level patterns and test the effects of dispersal-related species traits and phylogeny on abundance–distance relationships. Support for the hypothesis is dependent on taxonomic group, with abundant-centre patterns being more pronounced for plants but non-significant when summarised across all animals. Dispersal capability does not explain abundance–distance relationships in animals but likely explains abundance patterns in non-woody plants. Phylogeny improves models of abundance–distance patterns for plants but not for animals. Despite this, controlling for phylogeny yields non-significant group-level results for plants, suggesting that only certain, phylogenetically clustered plant groups may conform to abundant-centre patterns. Overall, we demonstrate that abundant-centre patterns are not a general ecological phenomenon; they tend to not apply to animals but can manifest in certain plant groups, depending on dispersal capabilities and evolutionary histories. Leveraging species’ traits that account for dispersal improves models of abundant-centre patterns across geographic space.