2026/06/16 by Julia Gabriele Dani, Olivier Chauveau, Verônica Aydos Thode +4
Agricultural and Biological Sciences · Biochemistry, Genetics and Molecular Biology · #Plant Diversity and Evolution #Plant and animal studies #Plant biochemistry and biosynthesis
paper · doi:10.1093/botlinnean/boag065
Abstract Floral oil is a highly specialized reward secreted by dense areas of glandular trichomes known as elaiophores. Tigridieae (Iridaceae), a predominantly South American tribe represented by two main clades, A and B, exhibits diverse floral rewards, including oil, a rare resource restricted to few specialized lineages. To evaluate whether elaiophores influenced diversification in Cypella and closely related genera (Clade A), we generated a dated phylogeny, clarified the definition of elaiophores in Tigridieae, and explored diversification patterns. A well-sampled, time-calibrated phylogeny was inferred using nine DNA regions, three nuclear and six plastidial, for 61 taxa, including 32 newly generated sequences and representatives of all genera of Tigridieae Clade A. Divergence times were estimated in BEAST, diversification rates were analysed using RevBayes and Bayesian analysis of macroevolutionary mixtures. Trait-dependent diversification was tested using state-dependent speciation and extinction models. We recovered six well-supported major clades and revealed that the most species-rich genera, Calydorea, Cypella, and Herbertia, were not monophyletic. Our findings support a broader view of floral evolution driven by diffuse selective pressures within complex pollination systems, suggesting that oil-based rewards in Tigridieae Clade A evolved through shifts from specialized to more generalized adaptive strategies. These findings provide valuable insights into reward evolution in angiosperms.