Data from: Effects of frugivore species pool and seed size on the diversity and functional composition of frugivores visiting fruiting trees

The relationship between biodiversity and ecosystem functioning in seed
dispersal remains understudied despite its critical role in maintaining
plant diversity in the tropics. Field studies on this relationship are
often confounded by environmental and phylogenetic variations across
species richness gradients. We examined how overall avian frugivore
species richness at a site influenced the frugivore richness, visitation
rates, and functional composition of two key effect traits⸺beak width and
hand-wing index⸺on fruiting trees. Across six sites in tropical Asia,
spanning a sevenfold gradient in frugivore species richness but with
similar forest types and phylogenetically nested frugivore communities, we
recorded 34,014 interactions between 134 avian frugivores and 131 plant
species. Our results provide some support for the biodiversity-ecosystem
functioning relationship, as higher overall frugivore species richness
increased the number of frugivore species visiting individual fruiting
trees but not the functional composition of frugivores. Seed size had a
stronger influence on the frugivore species richness, visitation rates,
and the beak size of visiting frugivores, highlighting the dominant role
of morphological trait matching in influencing plant-frugivore
interactions. Our findings suggest functional redundancy in certain
aspects of seed dispersal effectiveness due to density compensation and
the presence of key seed disperser lineages in species-poor sites.