Disentangling enabler and adaptive traits across habitat shifts in a large neotropical plant clade

Plant lineages tend to retain their ancestral environments, yet some successfully shift into new habitats. However, the factors that enable certain lineages to colonize novel environments while others fail to do so remain unclear. We tested whether vegetative traits function as enablers of habitat transitions, whereas reproductive traits evolve primarily as adaptive responses following these shifts. We analyzed 12 vegetative and 7 reproductive traits across 689 species of Neotropical Myrtaceae. Habitats were characterized using biome categories and multiple climatic gradients. Using a set of trait evolution models, we quantified trait-environment matching and evaluated whether trait evolution preceded or followed habitat transitions. Vegetative traits showed stronger trait-environment matching and more frequently acted as enablers, while reproductive traits displayed both enabler and adaptive patterns. Transitions into harsher environments were generally associated with a greater number of enabler traits. Habitat shifts are associated with a combination of enabler and adaptive patterns that vary across trait types and environments. Reproductive traits may contribute to colonization more than often assumed, and colonization of harsh environments may require more enabler trait combinations, highlighting that different trait-evolutionary dynamics may underlie transitions into different habitats.