Evolution of leafy liverworts (Jungermanniidae, Marchantiophyta): estimating divergence times from chloroplast DNA sequences using penalized likelihood with integrated fossil evidence

Based on chloroplast DNA sequences we develop a phylogenetic hypothesis of the diversification of liverworts (Marchantiophyta) with an extant diversity of about 6,000 species. Divergence time estimates obtained using penalized likelihood with integrated fossil evidence suggest a Late Ordovician origin of Marchantiophyta, a separation ofHaplomitriopsida from the remainder of liverworts in the Early Devonian, a split of Jungermanniopsida and Marchantiopsida in the Late Devonian, and a separation of Metzgeriidae and Jungermanniidae in the Late Carboniferous. Leafy liverworts (Jungermanniidae) with an extant diversity of ca. 4,500 species split into Porellales and Jungermanniales in the Early-Middle Permian. Our data provide evidence for a diversification of Jungermanniidae in the Triassic-perhaps coinciding with the recovery of terrestrial vegetation from the Perm/Trias extinction-and an enhanced diversification in the Cretaceous and Early Tertiary. The latter diversification events may coincide with the establishment of modern rainforests in the Late Cretaceous to Early Tertiary that were dominated by derived groups ofangiosperms. In addition, the Late Mesozoic and Early Tertiary diversification of leafy liverworts may have also been influenced by drastic changes in the geographical structure of the land masses and the global climate.