title: DNA taxonomy, cryptic speciation and diversification of the Neotropical-African liverwort, Marchesinia brachiata (Lejeuneaceae, Porellales).
abstract: The Neotropical-African liverwort Marchesinia brachiata has long been regarded as a polymorphic species. This hypothesis is examined using a dataset including sequences of the nuclear internal transcribed spacer region and the plastidic trnL-trnF region of 39 Marchesinia accessions. Maximum parsimony, maximum likelihood and Bayesian analyses indicate that Marchesinia robusta is nested within M. brachiata s.l. The molecular topologies support at least three partly sympatric biological species within M. brachiata s.l., the Neotropical M. bongardiana and M. languida, and the Neotropical-African M. brachiata s.s. These species are incompletely separated by subtle differences in underleaf shape and leaf dentation. Long branches within M. brachiata s.s. suggest ongoing speciation processes that are not yet reflected in distinguishable morphological variation. Divergence time estimates based on nrITS sequence variation and the liverwort fossil record indicate an establishment of the species M. bongardiana, M. brachiata, M. languida, M. madagassa, and M. robusta in the Late Oligocene and Miocene. The intraspecific diversity shows distinctive patterns with evidence for constant accumulation of genetic diversity in M. robusta and M. brachiata whereas M. bongardiana and M. languida likely went through a recent extinction or expansion process as indicated by the bottleneck pattern of genetic diversity. The tropical American-African disjunction of M. brachiata is the result of dispersal rather than Western Gondwanan vicariance.
authors.affiliation: Department of Systematic Botany, Albrecht von Haller Institute of Plant Sciences, Untere Karspüle 2, 37073 Göttingen, Germany. jheinri@uni-goettingen.de
authors.forename: Jochen
authors.initials: J
authors.lastname: Heinrichs
authors.forename: Fanny
authors.initials: F
authors.lastname: Klugmann
authors.forename: Jörn
authors.initials: J
authors.lastname: Hentschel
authors.forename: Harald
authors.initials: H
authors.lastname: Schneider
mesh_terms: D001499:Bayes Theorem; D018744:DNA, Plant / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D019143:Evolution, Molecular; D049810:Genetic Speciation; D014644:Genetic Variation; D005843:Geography; D035926:Hepatophyta / Q000145:classification / Q000235:genetics*; D016013:Likelihood Functions; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D018744:DNA, Plant; D021903:DNA, Ribosomal Spacer