Data from: Selection on fruit traits is mediated by the interplay between frugivorous birds, fruit flies, parasitoid wasps, and seed-dispersing ants

Every organism on Earth must cope with a multitude of species interactions
both directly and indirectly throughout its life cycle. However, how
selection from multiple species occupying different trophic levels affects
diffuse mutualisms has received little attention. As a result, how a given
species amalgamates the combined effects of selection from multiple
mutualists and antagonists to enhance its own fitness remains little
understood. We investigated how multispecies interactions (frugivorous
birds, ants, fruit flies, and parasitoid wasps) generate selection on
fruit display traits in a seed dispersal mutualism. We used structural
equation models to assess whether seed dispersers (frugivorous birds and
ants) exerted phenotypic selection on fruit and seed traits in the Spiny
Hackberry (Celtis ehrenbergiana), a fleshy-fruited tree, and how these
selection regimes were influenced by fruit fly infestation and wasp
parasitoidism levels. Birds exerted negative correlational selection on
the combination of fruit crop size and mean seed weight, favoring either
large crops with small seeds or small crops with large seeds. Parasitoids
selected plants with higher fruit fly infestation levels, and fruit flies
exerted positive directional selection on fruit size, which was positively
correlated with seed weight. Therefore, higher parasitoidism indirectly
correlated with higher plant fitness through increased bird fruit removal.
In addition, ants exerted negative directional selection on mean seed
weight. Our results show that strong selection on phenotypic traits may
still arise in perceived diffuse species interactions. Overall, we
emphasize the need to consider diverse direct and indirect partners to
achieve a better understanding of the mechanisms driving phenotypic trait
evolution in multispecies interactions.