Temperate-tropical transitions are linked with shifts in the structure of evolutionary integration in Vitaceae leaves

Abstract

Understanding how the intrinsic ability of populations and species to meet shifting selective demands shapes evolutionary patterns over both short and long timescales is a major question in biology. One major axis of evolutionary flexibility can be measured by phenotypic integration and modularity. The strength, scale, and structure of integration may constrain or catalyze evolution in the face of new selective pressures. We analyze a dataset of seven leaf measurements across Vitaceae to examine whether the structure of macroevolutionary integration is linked to transitions between temperate and tropical habitats by examining how the structure of integration shifts at discrete points along a phylogeny. We also examine these patterns in light of lineage diversification rates to understand how and whether patterns in the evolvability of complex multivariate phenotypes are linked to higher-level macroevolutionary dynamics. We found that shifts in the structure of macroevolutionary integration in leaves coincide with early colonization events into new climates and that lineages that are more climatically labile are more weakly integrated overall. These more evolutionarily flexible lineages also had higher lineage turnover, suggesting a link between shifting vectors of selection, internal constraint, and lineage persistence in the face of changing environments.