title: Reconstructing relative genome size of vascular plants through geological time.
abstract: The strong positive relationship evident between cell and genome size in both animals and plants forms the basis of using the size of stomatal guard cells as a proxy to track changes in plant genome size through geological time. We report for the first time a taxonomic fine-scale investigation into changes in stomatal guard-cell length and use these data to infer changes in genome size through the evolutionary history of land plants. Our data suggest that many of the earliest land plants had exceptionally large genome sizes and that a predicted overall trend of increasing genome size within individual lineages through geological time is not supported. However, maximum genome size steadily increases from the Mississippian (c. 360 million yr ago (Ma)) to the present. We hypothesise that the functional relationship between stomatal size, genome size and atmospheric CO2 may contribute to the dichotomy reported between preferential extinction of neopolyploids and the prevalence of palaeopolyploidy observed in DNA sequence data of extant vascular plants.
authors.affiliation: Division of Agricultural and Environmental Sciences, The School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, LE12 5RD, UK.
authors.forename: Barry H
authors.initials: BH
authors.lastname: Lomax
authors.affiliation: School of Geography, Earth and Environmental Sciences, The University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Hilton
authors.affiliation: Jodrell Laboratory, Royal Botanic Gardens Kew, Richmond, Surrey, TW9 3AB, UK.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Bateman
authors.affiliation: Department of Biology, Texas State University San Marcos, San Marcos, TX, 78666, USA.
authors.forename: Garland R
authors.initials: GR
authors.lastname: Upchurch
authors.affiliation: Division of Agricultural and Environmental Sciences, The School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, LE12 5RD, UK.|Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
authors.forename: Janice A
authors.initials: JA
authors.lastname: Lake
authors.affiliation: Jodrell Laboratory, Royal Botanic Gardens Kew, Richmond, Surrey, TW9 3AB, UK.
authors.forename: Ilia J
authors.initials: IJ
authors.lastname: Leitch
authors.affiliation: Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA, 93407, USA.
authors.forename: Avery
authors.initials: A
authors.lastname: Cromwell
authors.affiliation: Department of Biological Sciences, California Polytechnic State University, San Luis Obispo, CA, 93407, USA.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Knight
mesh_terms: D005075:Biological Evolution; D002245:Carbon Dioxide / Q000378:metabolism; D002965:Classification; D059646:Genome Size; D054046:Plant Stomata / Q000033:anatomy & histology; D010944:Plants / Q000235:genetics*
chemical_list: D002245:Carbon Dioxide
keywords: angiosperm; ecology; evolution; genome; gymnosperm; palaeobotany; palaeopolyploidy; polyploidy