A framework phylogeny of the diverse guinea-flowers (Hibbertia, Dilleniaceae) using high-throughput sequence data

Hibbertia is the largest genus in Dilleniaceae and one of the largest Australian plant genera, with ~350 current and more than 100 known undescribed species in Australia. We present the first published phylogeny based on rigorous sampling of Hibbertia. As part of Genomics for Australian Plants Stage II, 95 Hibbertia species were newly sequenced using Angiosperm353, OzBaits nuclear and OzBaits plastid bait sets, resulting in 402 nuclear and 79 plastid loci that were subsampled to retain the most phylogenetically useful 300 and 60 loci respectively. Nuclear and plastid phylogenies were reconstructed using concatenation and coalescent approaches, and further analysed using Quartet Sampling. We found that Hibbertia and the four subgenera within the genus are robustly supported as monophyletic and recovered 14 major clades, supported in both datasets, within the two largest subgenera (subg. Hemistemma and subg. Hibbertia). However, many relationships between these major clades are unresolved and discordant. Some incongruence was also detected between the plastid and nuclear trees. Discordance was particularly high in the largest eastern Australian clade of subg. Hemistemma. Possible causes of this discordance, and relationships between and within these major clades, are discussed.