Phylogenetic relationships and character evolution analysis of Saxifragales using a supermatrix approach

Premise of the study: We sought novel evolutionary insights for the highly diverse Saxifragales by constructing a large phylogenetic tree encompassing 36.8% of the species-level biodiversity. Methods: We built a phylogenetic tree for 909 species of Saxifragales and used this hypothesis to examine character evolution for: annual or perennial habit, woody or herbaceous habit, ovary position, petal number, carpel number, and stamen: petal ratio. We employed likelihood approaches to investigate the effect of habit and life history on speciation and extinction within this clade. Key results: Two major shifts occurred from a woody ancestor to the herbaceous habit, with multiple secondary changes from herbaceous to woody. Transitions among superior, subinferior, and inferior ovaries appear equiprobable. A major increase in petal number is correlated with a large increase in carpel number; these increases have co-occurred multiple times in Crassulaceae. Perennial or woody lineages have higher r...