Data for: Colonization and extinction processes mediate environmental effects on the phylogenetic diversity of invertebrate communities

Phylogeny offers a powerful framework for understanding mechanisms driving
community assembly. Yet, most empirical studies in community phylogenetics
rely on observational approaches. In this study, we explore how two
important drivers of community assembly — habitat size and predator
presence — shape species richness and phylogenetic relatedness of prey
communities by altering colonization and extinction processes. Using
bromeliad invertebrate communities as our study system, we combined
surveys of natural communities with experiments that manipulated habitat
size and predator presence. Colonization and extinction were isolated in
separate experiments to test whether the effects of habitat size and
predator presence differed across stages of community assembly. Following
species-area theory, we expected larger habitats to increase species
richness and, given the strong consumptive effects of the top predator (a
damselfly larva), we expected species richness to decline in the presence
of predators. Under a community phylogenetics framework, if traits
mediating responses to these factors are phylogenetically conserved, we
expect the phylogenetic structure of the community (i.e., relatedness) to
have deterministic patterns along both gradients. Specifically, if habitat
size functions as an environmental filter, small bromeliads would host
phylogenetically clustered assemblages; alternatively, if it functions as
a mediator for coexistence among close relatives, larger habitats would
exhibit greater relatedness. Likewise, we expected the generalist top
predators to increase relatedness when closely related taxa have shared
defensive traits. As traits mediating community assembly may vary in their
phylogenetic distribution across lineages, we also anticipated relatedness
patterns to vary across taxonomic scales. We found a positive effect of
habitat size on species richness, which was driven by colonization
mechanisms. Habitat size also affected relatedness, but the direction
depended on taxonomic scale, with positive relationships at broad scales
and negative relationships at narrower scales. By contrast, predators
reduced species richness through extinction mechanisms, although these
effects were masked in natural communities by continuous replacement of
individuals through colonization. Predator effects on relatedness were
variable across taxonomic scales, suggesting the involvement of multiple
traits at different phylogenetic depths. Together, our findings highlight
the complex interplay between environmental factors and community assembly
in structuring taxonomic and phylogenetic dimensions of diversity.