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 there an association between the timing of diversification of species, niche and traits?
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 first diversified 15 million years ago, driven by the Earth's cooling climate. It wasn't, however, until about five million years later that these plants invaded new habitats and evolved new physical traits. This suggests an evolutionary pattern never observed before, involving a strong temporal lag with diversification preceding niche and phenotype evolution in temperate biotas.