Research Divergence times and the evolution of morphological complexity in an early land plant lineage (Marchantiopsida) with a slow molecular rate Juan Carlos Villarreal A.1,3,4, Barbara J. Crandall-Stotler2, Michelle L. Hart1, David G. Long1 and Laura L. Forrest1 1Royal Botanic Gardens Edinburgh, 20A Inverleith Row, Edinburgh, EH3 5LR, UK; 2Department of Plant Biology, Southern Illinois University, Carbondale, IL 62901, USA; 3Present address: Smithsonian Tropical Research Institute, Ancon, 0843-03092 Panama, Republic of Panama; 4Present address: Departement de Biologie, Universite Laval, Quebec, Canada G1V 0A6 Summary Authors for correspondence: We present a complete generic-level phylogeny of the complex thalloid liverworts, a lineage Juan Carlos Villarreal A that includes the model system Marchantia polymorpha. The complex thalloids are remark- Tel: +1418 656 3180 able for their slow rate of molecular evolution and for being the only extant plant lineage to Email:
[email protected] differentiate gas exchange tissues in the gametophyte generation. We estimated the diver- Laura L. Forrest gence times and analyzed the evolutionary trends of morphological traits, including air cham- Tel: + 44(0) 131248 2952 bers, rhizoids and specialized reproductive structures. Email:
[email protected] A multilocus dataset was analyzed using maximum likelihood and Bayesian approaches. Received: 29 June 2015 Relative rates were estimated using local clocks. Accepted: 15 September 2015 Our phylogeny cements the early branching in complex thalloids. Marchantia is supported in one of the earliest divergent lineages. The rate of evolution in organellar loci is slower than New Phytologist (2015) for other liverwort lineages, except for two annual lineages.