Turnover or intraspecific trait variation: explaining functional variability in a neotropical anuran metacommunity

Abstract

Trait variation across environmental gradients results from two processes: intraspecific variation (ITV) and turnover. Trait plasticity promotes intraspecific variation and can mediate, increasing or decreasing, interspecific variation. Here we evaluate patterns of ITV and trait-environment relationships in an anuran metacommunity from southern Brazil. We hypothesize that the contribution of ITV and turnover to trait variation and trait-environment relationships should vary between groups of habitats use and traits. To test this, we sampled anurans in 33 ponds and selected the eight most abundant species, which were grouped as arboreal or aquatic-terrestrial according to their use of space. We evaluated the following traits: head shape, eye size and position, limb length and body mass. We divided variation in community trait composition into ITV, variability due to turnover, and also the covariation between them. We modelled trait-environment relationships using linear mixed-effect models. ITV and turnover contributed similarly across traits, but differentially between sets of species. Trait variation seems to be mostly driven by ITV in arboreal anurans and by turnover in aquatic-terrestrial species. Depth, distance between ponds, area of Pinus surrounding the ponds, and types of pond vegetation and substrate strongly influenced trait variation, but their relative contribution depended on the analysed traits and species sets. The dominant contribution of ITV towards the variation of head shape and eye size and position suggests the existence of intraspecific adaptations to microhabitats, while turnover dominance in the variation of body mass and limb length suggests differences in dispersal and trophic segregation between species.