Flower evolution in Ericales: A total-evidence approach including extant and fossil flowers

The inclusion of fossil flowers into ancestral statereconstructions is critical for understanding flower evolution and promises new insights by cap-turing past morphological diversity. The asteridorder Ericales is characterized by highly diversefloral structures and a rich fossil record, makingit well-suited for a study on flower evolution in-tegrating the fossil record. We used a Bayesiantip-dating approach with a total-evidence data-set and the fossilised birth-death model to jointlyinfer the position of the 13 fossils among 413 extantspecies of Ericales, considering both morpholo-gy and age. We reconstructed ancestral statesfor 38 floral characters using Bayesian and max-imum likelihood methods, for 21 of the 22 familiescurrently recognised in the order as well as sixwell-supported supra-familial clades. Accountingfor uncertainty of fossil position influences the reconstructed ancestral states, generally introduc-ing more uncertainty in reconstructed states. Weshow that the ancestral flower of Ericales exhibitsboth typical characteristics of its sister group, thelarge clade comprising lamiids and campanulids(e.g. fused petals), and plesiomorphic features(e.g. actinomorphic perianth) inherited from theirPentapetalae ancestor. In combining a quanti-tative approach to infer fossil phylogenetic rela-tionships with multiple approaches to reconstructancestral states, we facilitate a deeper under-standing of flower evolution of Ericales.