@ARTICLE{TreeBASE2Ref23090, author = {Juan Carlos Villarreal and Susanne S Renner}, title = {A review of molecular-clock calibrations and substitution rates in liverworts, mosses, and hornworts, and a timeframe for a taxonomically cleaned-up genus Nothoceros}, year = {2014}, keywords = {Bryophyte fossils, calibration approaches, cross validation, plastid DNA substitution rates, nuclear ITS, substitution rates}, doi = {}, url = {http://}, pmid = {}, journal = {Molecular Phylogenetics and Evolution}, volume = {}, number = {}, pages = {}, abstract = {Absolute times from calibrated DNA phylogenies can be used to infer lineage diversification, the origin of new ecological niches, or the role of long distance dispersal in shaping current distribution patterns. Molecular-clock dating of non-vascular plants, however, has lagged behind, perhaps because workers are insufficiently aware of suitable calibration approaches. Here, we review dating studies that have focused on bryophytes with several goals in mind, (i) To facilitate cross-validation by comparing rates and times obtained so far; (ii) to summarize rates that have yielded plausible results and that could be used in future studies; and (iii) to calibrate a species-level phylogeny for Nothoceros, a model for plastid genome evolution in hornworts. Including the present work, there have been 18 molecular clock studies of liverworts, mosses, or hornworts, all using relaxed clock models, the majority with fossil calibrations, a few with geological calibrations or dated with previously published plastid substitution rate. Over half the studies cross-validated inferred divergence times by using alternative calibration approaches. Plastid substitution rate inferred for ?bryophytes? are in line with those found in benchmark angiosperm studies, implying that bryophyte clock models can be calibrated either with average substitution rates or with fossils, with the two approaches testing and cross-validating each other. Our phylogeny of Nothoceros is based on 44 accessions representing all suspected species and a matrix of six markers of nuclear, plastid, and mitochondrial DNA. Based on these data, Nothoceros comprises 10 species, nine in the Americas and one in New Zealand (N. giganteus), with the divergence between the New Zealand species and its Chilean sister species dated to the Miocene and therefore due to long-distance dispersal. Based on the new tree, we formally transfer two species of Megaceros that are nested inside Nothoceros, resulting in the new combinations N. minarum (Nees) J.C.Villarreal and N. schizophyllus (Gottsche ex Steph.) J.C.Villarreal, and we also newly synonymize eight names described in Megaceros.} }

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