title: Genome evolution of ferns: evidence for relative stasis of genome size across the fern phylogeny.
abstract: The genome evolution of ferns has been considered to be relatively static compared with angiosperms. In this study, we analyse genome size data and chromosome numbers in a phylogenetic framework to explore three hypotheses: the correlation of genome size and chromosome number, the origin of modern ferns from ancestors with high chromosome numbers, and the occurrence of several whole-genome duplications during the evolution of ferns. To achieve this, we generated new genome size data, increasing the percentage of fern species with genome sizes estimated to 2.8% of extant diversity, and ensuring a comprehensive phylogenetic coverage including at least three species from each fern order. Genome size was correlated with chromosome number across all ferns despite some substantial variation in both traits. We observed a trend towards conservation of the amount of DNA per chromosome, although Osmundaceae and Psilotaceae have substantially larger chromosomes. Reconstruction of the ancestral genome traits suggested that the earliest ferns were already characterized by possessing high chromosome numbers and that the earliest divergences in ferns were correlated with substantial karyological changes. Evidence for repeated whole-genome duplications was found across the phylogeny. Fern genomes tend to evolve slowly, albeit genome rearrangements occur in some clades.
authors.affiliation: Department of Life Sciences, Natural History Museum, London, SW7 5BD, UK.|School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK.
authors.forename: James
authors.initials: J
authors.lastname: Clark
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey, TW8 3DS, UK.
authors.forename: Oriane
authors.initials: O
authors.lastname: Hidalgo
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey, TW8 3DS, UK.
authors.forename: Jaume
authors.initials: J
authors.lastname: Pellicer
authors.affiliation: Shenzhen Key Laboratory of Southern Subtropical Plant Diversity, Fairylake Botanical Garden, Shenzhen & The Chinese Academy of Sciences, Shenzhen, 518004, China.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Life Sciences, Natural History Museum, London, SW7 5BD, UK.
authors.forename: Jeannine
authors.initials: J
authors.lastname: Marquardt
authors.affiliation: 18, Rue des Capucines, F-97431, La Plaine des Palmistes, La Réunion, France.
authors.forename: Yannis
authors.initials: Y
authors.lastname: Robert
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey, TW8 3DS, UK.|Plant Gateway, 5 Talbot Street, Hertford, Hertfordshire, SG13 7BX, UK.
authors.forename: Maarten
authors.initials: M
authors.lastname: Christenhusz
authors.affiliation: Shenzhen Key Laboratory of Southern Subtropical Plant Diversity, Fairylake Botanical Garden, Shenzhen & The Chinese Academy of Sciences, Shenzhen, 518004, China.
authors.forename: Shouzhou
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Science, Royal Botanic Garden Edinburgh, Edinburgh, EH3 5LR, UK.
authors.forename: Mary
authors.initials: M
authors.lastname: Gibby
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, Surrey, TW8 3DS, UK.
authors.forename: Ilia J
authors.initials: IJ
authors.lastname: Leitch
authors.affiliation: Department of Life Sciences, Natural History Museum, London, SW7 5BD, UK.|School of Life Sciences, Sun Yatsen University, Guangzhou, 510275, Guangdong, China.
authors.forename: Harald
authors.initials: H
authors.lastname: Schneider
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics; D019143:Evolution, Molecular; D029624:Ferns / Q000235:genetics*; D059646:Genome Size; D018745:Genome, Plant; D010802:Phylogeny
keywords: DNA C-values; chromosome number; chromosome structure; genome size; macroevolution; phylogeny; polyploidy; pteridophytes