Functional distance does not predict interspecific synchrony, but functional diversity directly affects community stability

Several studies attempt to understand the mechanisms underlying compensatory and synchronous dynamics, and how these mechanisms relate to community stability. For this purpose, the use of functional traits, in theory, would allow for a direct evaluation of whether functional similarity generates compensatory dynamics or interspecific synchrony. Likewise, a trait-based approach is also needed to evaluate the effect of functional biodiversity on community stability. Using phytoplankton data from the Cana Brava Reservoir (Goiás State, Brazil), we tested whether interspecific synchrony depends on functional distance and whether variability in total abundance depends on community synchrony and functional diversity. We did not find a significant relationship between interspecific synchrony and functional distance. However, we found a predominance of positive correlations between pairs of species and a strong negative relationship between functional diversity and community variability. Our results suggest that interspecific synchrony cannot be reliably predicted by functional distance. Given the predominance of positive synchrony, we indirectly infer that environmental variations similarly controlled the dynamics of most species. Our findings also highlight the stabilizing role of functional diversity.