title: Molecular phylogeny of the leafy liverwort Lejeunea (Porellales): evidence for a neotropical origin, uneven distribution of sexual systems and insufficient taxonomy.
abstract: BACKGROUND
  Lejeunea is a largely epiphytic, subcosmopolitan liverwort genus with a complex taxonomic history. Species circumscriptions and their relationships are subject to controversy; biogeographic history and diversification through time are largely unknown.
  
  
  RESULTS
  We employed sequences of two chloroplast regions (trnL-trnF, rbcL) and the nuclear ribosomal ITS region of 332 accessions to explore the phylogeny of the Harpalejeunea-Lejeunea-Microlejeunea complex. Lejeunea forms a well-supported clade that splits into two main lineages corresponding to L. subg. Lejeunea and L. subg. Crossotolejeunea. Neotropical accessions dominate early diverging lineages of both main clades of Lejeunea. This pattern suggests an origin in the Neotropics followed by several colonizations from the Neotropics into the Paleotropics and vice versa. Most Afro-Madagascan clades are related to Asian clades. Several temperate Lejeunea radiations were detected. Eighty two of the 91 investigated Lejeunea species could be identified to species level. Of these 82 species, 54 were represented by multiple accessions (25 para- or polyphyletic, 29 monophyletic). Twenty nine of the 36 investigated species of L. subg. Lejeunea were monoicous and 7 dioicous. Within L. subg. Crossotolejeunea, 15 of the 46 investigated species were monoicous and 31 dioicous. Some dioicous as well as some monoicous species have disjunct ranges.
  
  
  CONCLUSIONS
  We present the first global phylogeny of Lejeunea and the first example of a Neotropical origin of a Pantropical liverwort genus. Furthermore, we provide evidence for the Neotropics as a cradle of Lejeunea lineages and detect post-colonization radiations in Asia, Australasia, Afro-Madagascar and Europe. Dioicy/monoicy shifts are likely non-randomly distributed. The presented phylogeny points to the need of integrative taxonomical studies to clarify many Lejeunea binomials. Most importantly, it provides a framework for future studies on the diversification of this lineage in space and time, especially in the context of sexual systems in Lejeuneaceae.
authors.affiliation: Systematic Botany and Mycology, Faculty of Biology, Ludwig Maximilian University, Munich, Germany ; Department of Systematic Botany, Albrecht von Haller Institute of Plant Sciences, Georg August University, Göttingen, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Heinrichs
authors.affiliation: Department of Systematic Botany, Albrecht von Haller Institute of Plant Sciences, Georg August University, Göttingen, Germany.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Dong
authors.affiliation: Mittlere Letten 11, Herdwangen-Schönach, Germany.
authors.forename: Alfons
authors.initials: A
authors.lastname: Schäfer-Verwimp
authors.affiliation: Botany Department, Institute of Biology, Eszterházy College, Eger, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Pócs
authors.affiliation: Systematic Botany and Mycology, Faculty of Biology, Ludwig Maximilian University, Munich, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Feldberg
authors.affiliation: Department of Systematic Botany, Albrecht von Haller Institute of Plant Sciences, Georg August University, Göttingen, Germany.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Czumaj
authors.affiliation: Courant Research Centre Geobiology, Georg August University, Göttingen, Germany.
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Schmidt
authors.affiliation: Courant Research Centre Geobiology, Georg August University, Göttingen, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Reitner
authors.affiliation: Royal Botanic Gardens & Domain Trust, Sydney, Australia.
authors.forename: Matt A M
authors.initials: MA
authors.lastname: Renner
authors.affiliation: Department of Systematic Botany with Herbarium Haussknecht and Botanical Garden, Friedrich Schiller University, Jena, Germany.
authors.forename: Joern
authors.initials: J
authors.lastname: Hentschel
authors.affiliation: Naturalis Biodiversity Center, Leiden, The Netherlands ; Leiden University, Leiden, The Netherlands.
authors.forename: Michael
authors.initials: M
authors.lastname: Stech
authors.affiliation: The Natural History Museum London, London, United Kingdom.
authors.forename: Harald
authors.initials: H
authors.lastname: Schneider
mesh_terms: D018744:DNA, Plant / Q000235:genetics; D019143:Evolution, Molecular; D035926:Hepatophyta / Q000145:classification / Q000235:genetics*; D010802:Phylogeny
chemical_list: D018744:DNA, Plant