title: Evolution of sexual systems, dispersal strategies and habitat selection in the liverwort genus Radula.
abstract: • Shifts in sexual systems are among the most common and important transitions in plants and are correlated with a suite of life-history traits. The evolution of sexual systems and their relationships to gametophyte size, sexual and asexual reproduction, and epiphytism are examined here in the liverwort genus Radula. • The sequence of trait acquisition and the phylogenetic correlations between those traits was investigated using comparative methods. • Shifts in sexual systems recurrently occurred from dioecy to monoecy within facultative epiphyte lineages. Production of specialized asexual gemmae was correlated to neither dioecy nor strict epiphytism. • The significant correlations among life-history traits related to sexual systems and habitat conditions suggest the existence of evolutionary trade-offs. Obligate epiphytes do not produce gemmae more frequently than facultative epiphytes and disperse by whole gametophyte fragments, presumably to avoid the sensitive protonemal stage in a habitat prone to rapid changes in moisture availability. As dispersal ranges correlate with diaspore size, this reinforces the notion that epiphytes experience strong dispersal limitations. Our results thus provide the evolutionary complement to metapopulation, metacommunity and experimental studies demonstrating trade-offs between dispersal distance, establishment ability, and life-history strategy, which may be central to the evolution of reproductive strategies in bryophytes.
authors.affiliation: Institut de Botanique, Université de Liege, B-22 Sart Tilman, B-4000 Liege, Belgium.|Biology Department, Duke University, Box 90338 Durham, NC 27708, USA.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Devos
authors.affiliation: National Herbarium of New South Wales, Royal Botanic Gardens Sydney, Mrs Macquaries Road, Sydney, NSW 2000, Australia.
authors.forename: Matt A M
authors.initials: MAM
authors.lastname: Renner
authors.affiliation: Dept. Systématique et Evolution, Muséum National d'Histoire Naturelle, 57 rue Cuvier, 75231 Paris cedex 05, France.
authors.forename: Robbert
authors.initials: R
authors.lastname: Gradstein
authors.affiliation: Biology Department, Duke University, Box 90338 Durham, NC 27708, USA.
authors.forename: A Jonathan
authors.initials: AJ
authors.lastname: Shaw
authors.affiliation: Institut de Botanique, Université de Liege, B-22 Sart Tilman, B-4000 Liege, Belgium.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Laenen
authors.affiliation: Institut de Botanique, Université de Liege, B-22 Sart Tilman, B-4000 Liege, Belgium.
authors.forename: Alain
authors.initials: A
authors.lastname: Vanderpoorten
mesh_terms: D001499:Bayes Theorem; D005075:Biological Evolution; D018742:DNA, Chloroplast / Q000235:genetics; D017753:Ecosystem; D035926:Hepatophyta / Q000502:physiology*; D016013:Likelihood Functions; D008954:Models, Biological; D010802:Phylogeny; D019655:Quantitative Trait, Heritable; D058614:Seed Dispersal / Q000502:physiology*
chemical_list: D018742:DNA, Chloroplast