Data from: Drivers of individual niche variation in coexisting species

1. Although neglected by classic niche theory, individual variation is now
recognized as a prevalent phenomenon in nature with evolutionary and
ecological relevance. Recent theory suggests that differences in
individual variation across competitors can affect species coexistence and
community patterns. However, the degree of individual variation is
flexible across wild populations and we still know little about the
ecological drivers of this variation across populations of single species
and, especially, across coexisting species. 2. Here we aimed to (i)
elucidate the major drivers of individual niche variation in natural
communities and (ii) to determine how consistent this variation is across
coexisting species and communities. 3. We analyzed natural patterns of
individual-level niche variation in four species of coexisting generalist
frogs across a wide range of tropical communities. Specifically, we used
gut contents and stable isotopes (δ13C and δ15N) from frog species and
their prey to quantify individual niche specialization. Then we combined
data on local community structure, availability of prey, phylogenetic
relationships, and predator-prey size models to test how this variation is
related to four ecological factors which are predicted to be key drivers
of individual specialization: intraspecific competition, interspecific
competition, ecological opportunity (i.e., diversity of resources), and
predation. 4. We found that the degree of individual trophic
specialization varied by up to nine-fold across populations within the
same species. This sizable variation in trophic specialization across
populations was at least partially explained by gradients of density of
competitors (both conspecifics and heterospecifics) and intraguild
predation. However, the specific relationships between individual
specialization and these ecological gradients were strongly
species-specific. As consequences, the identity of the species with more
individual variation changed among sites and there was typically no
spatial correlation in the degree of individual specialization across
co-existing species. 5. Our results show that individual niche
specialization within and across species can be strongly context-dependent
and that hierarchies of individual variation among coexisting species are
not necessarily consistent across communities. Recent theory suggests that
this pattern could lead to concurrent changes in competitive interactions
across sites and thereby could play a key role in species coexistence at
the landscape level. Our results suggest that individual variation across
and within coexisting species has the potential to affect not only species
coexistence at local communities, but also regional diversity patterns.