Phylogenetic signal in pollination networks varies in strength with pollinator type and community plant species richness

Phylogenetic constraints have been hypothesized to influence the complex network structure found in plant-pollinator communities. Here, I develop and test a conceptual model of factors that might modulate any signal of phylogenetic clustering of plants visited by individual pollinator species. Across 29 communities, pollinators visited weakly phylogenetically clustered plant species. Plant relatedness was positively correlated with community plant richness; and plants visited by versatile pollinators were phylogenetically random in small communities but became clustered as richness increased. However, these patterns were not explained by a simple dichotomous scoring of plants as restrictive or unrestrictive to unversatile pollinators. Collectively, these results suggest that constraints imposed by plant phylogeny on pollination networks are moderated by current ecological processes such as community assembly and pollinator foraging behaviour, but mechanisms are unclear. Future research should consider the opportunity for bidirectional interplay between ecological and phylogenetic effects.