Data from: Phylogenetic tree shape and the structure of mutualistic networks

Species community composition is known to alter the network of
interactions between two trophic levels, potentially affecting its
functioning (e.g. plant pollination success) and the stability of
communities. Phylogenies vary in shape with regard to the rate of
evolutionary change across a tree (influencing tree balance) and variation
in the timing of branching events (affecting the distribution of node ages
in trees), both of which may influence the structure of species
interaction networks. Because related species are likely to share many of
the traits that regulate interactions, the shape of phylogenetic trees may
provide some insights into the distribution of traits within communities,
and hence the likelihood of interaction among species. However, little
attention has been paid to the potential effects of changes in
phylogenetic diversity (PD) on interaction networks. Phylogenetic
diversity is influenced by species diversity within a community, but also
how distantly-related the constituent species are from one another. Here,
we evaluate the relationship between two important measures of
phylogenetic diversity (tree shape and age of nodes) and the structure of
plant-pollinator interaction networks using empirical and simulated data.
Whereas the former allows us to evaluate patterns in real communities, the
latter allows us to evaluate more systematically the relationship between
tree shape and network structure under three different models of trait
evolution. In empirical networks, less balanced plant phylogenies were
associated with lower connectance in interaction networks indicating that
communities with the descendants of recent radiations are more diverged
and specialized in their partnerships. In simulations, tree balance and
the distribution of nodes through time were included in the best models
for modularity, and the second best models for connectance and nestedness.
In models assuming random evolutionary change through time (i.e., Brownian
motion), less balanced trees and trees with nodes near the tips exhibited
greater modularity, whereas in models with an early burst of radiation
followed by relative stasis (i.e. early-burst models) more balanced trees
and trees with nodes near roots had greater modularity. Synthesis:
Overall, these results suggest that the shape of phylogenies can influence
the structure of plant-pollinator interaction networks. However, the
mismatch between simulations and empirical data indicate that no simple
model of trait evolution mimics that observed in real communities.