Data from: Environmental gradients and the evolution of successional habitat specialization: a test case with 14 Neotropical forest sites

1. Successional gradients are ubiquitous in nature, yet few studies have
systematically examined the evolutionary origins of taxa that specialize
at different successional stages. Here we quantify successional habitat
specialization in Neotropical forest trees and evaluate its evolutionary
lability along a precipitation gradient. Theoretically, successional
habitat specialization should be more evolutionarily conserved in wet
forests than in dry forests due to more extreme microenvironmental
differentiation between early and late successional stages in wet forest.
2. We applied a robust multinomial classification model to samples of
primary and secondary forest trees from 14 Neotropical lowland forest
sites spanning a precipitation gradient from 788 to 4000 mm annual
rainfall, identifying species that are old growth specialists and
secondary forest specialists in each site. We constructed phylogenies for
the classified taxa at each site and for the entire set of classified
taxa, and tested whether successional habitat specialization is
phylogenetically conserved. We further investigated differences in the
functional traits of species specializing in secondary vs. old-growth
forest along the precipitation gradient, expecting different trait
associations with secondary forest specialists in wet vs. dry forests
since water availability is more limiting in dry forests and light
availability more limiting in wet forests. 3. Successional habitat
specialization is non-randomly distributed in the angiosperm phylogeny,
with a tendency towards phylogenetic conservatism overall and a trend
toward stronger conservatism in wet forests than in dry forests. However,
the specialists come from all the major branches of the angiosperm
phylogeny, and very few functional traits showed any consistent
relationships with successional habitat specialization in either wet or
dry forests. 4. Synthesis: The niche conservatism evident in the habitat
specialization of Neotropical trees suggests a role for radiation into
different successional habitats in the evolution of species-rich genera,
though the diversity of functional traits that lead to success in
different successional habitats complicates analyses at the community
scale. Examining the distribution of particular lineages with respect to
successional gradients may provide more insight into the role of
successional habitat specialization in the evolution of species-rich taxa.