­Evolution of the most species-rich family of simple thalloid liverworts (Aneuraceae): a time-calibrated perspective into its evolutionary history and diversification

Abstract Aneuraceae is the largest family of the simple thalloid liverworts. Despite simple morphological features, this family is well-known for its unique ecology, cryptic diversity, and species-rich lineages. In this study, we explored the evolutionary history and diversification of the Aneuraceae. Investigating the effects of fossil calibrations on divergence time estimates and how recognizing cryptic species impacts macroevolutionary analyses. We used publicly available nucleotide sequences to reconstruct chronograms of Aneuraceae with representatives from subclass Metzgeriidae as outgroups. We also examined the consequences of different calibrations in chronogram reconstruction. Then, the resulting time-calibrated phylogeny was employed to reveal diversification dynamics with lineage through time plots (LTTPs), γ-statistics, and Bayesian Analysis of Macroevolutionary Mixtures (BAMM). The Aneuraceae had originated and created diversity since the Lower Carboniferous (352.75 Mya, 95%HPD: 505.79–264.59) to Upper Devonian. Lineage diversification of Aneuraceae species was consistent with late bursts of speciation with two significant rate shifts in genus Riccardia: one at the crown node of the genus and the other at the Neotropical clade. Including cryptic taxa resulted in an additional rate shift at the crown node of Aneura. Aneuraceae originated during the middle Palaeozoic Era, similar to other early terrestrial plants, although different fossil calibrations significantly affected the estimation of divergence dating. Two speciation rate shifts in Riccardia could be the results of asexual reproductive structure in this genus and climate changes in the Neotropics. Ecological conditions at the origin of the family and association with fungi might be associated with the increased diversification in this family.