Evolution takes place all the time. When shifts in environmental regimes provide ecological opportunities, diversification can happen fast. New ecological niches and phenotypic traits evolve, but what might explain shifts in rates—and is the timing of diversification of species, niche and traits associated?
Focusing on a major flowering plant clade—Saxifragales—a group of nearly 2,500 species encompassing trees such as sweet gum and shrubs such as gooseberry, authors of this study built a phylogenetic tree of 1,736 species and addressed macroevolutionary questions through analyses of traits and ecological niches, derived from 1.6 million GBIF-mediated occurrences and climate data.
Their results showed that in Saxifragales, species diversified first 15 million years ago, driven by the Earth's cooling climate. It wasn't, however, until about five million years later these plants invaded new habitats and evolved new physical traits. This suggests a never-before observed evolutionary pattern of a strong temporal lag with diversification preceeding niche and phenotype evolution in temperate biotas.