title: Genome size stability despite high chromosome number variation in Carex gr. laevigata.
abstract: OBJECTIVE
  In organisms with holocentric chromosomes like Carex species, chromosome number evolution has been hypothesized to be a result of fission, fusion, and/or translocation events. Negative, positive, or the absence of correlations have been found between chromosome number and genome size in Carex.
  
  
  METHODS
  Using the inferred diploid chromosome number and 80 genome size measurements from 26 individuals and 20 populations of Carex gr. laevigata, we tested the null hypothesis of chromosome number evolution by duplication and deletion of whole chromosomes.
  
  
  RESULTS
  Our results show a significant positive correlation between genome size and chromosome number, but the slope of such correlation supports the hypothesis of proliferation and removal of repetitive DNA fragments to explain genome size variation rather than duplication and deletion of whole chromosomes.
  
  
  CONCLUSIONS
  Our results refine the theory of the holokinetic drive: this mechanism is proposed to facilitate repetitive DNA removal (or any segmental deletion) when smaller homologous chromosomes are preferentially inherited, or repetitive DNA proliferation (or any segmental duplication) when larger homologs are preferred. This study sheds light on how karyotype evolution plays an important role in the diversification of the species of the genus Carex.
authors: Department of Integrative Ecology, Estación Biológica de Doñana (EBD-CSIC), Americo Vespucio sn 41092 Seville, Spain.
authors: Marcial
authors: M
authors: Escudero
authors: Department of Molecular Biology and Biochemical Engineering, Pablo de Olavide University, Carretera de Utrera Km 1 sn 41013 Seville, Spain.
authors: Enrique
authors: E
authors: Maguilla
authors: Centre for Functional Ecology, Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal.
authors: João
authors: J
authors: Loureiro
authors: Centre for Functional Ecology, Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal.
authors: Mariana
authors: M
authors: Castro
authors: Centre for Functional Ecology, Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal.
authors: Sílvia
authors: S
authors: Castro
authors: Department of Molecular Biology and Biochemical Engineering, Pablo de Olavide University, Carretera de Utrera Km 1 sn 41013 Seville, Spain.
authors: Modesto
authors: M
authors: Luceño
mesh_terms: D031255:Carex Plant / Q000235:genetics*; D032461:Chromosomes, Plant; D018744:DNA, Plant; D004171:Diploidy; D019143:Evolution, Molecular; D014644:Genetic Variation; D059646:Genome Size; D018745:Genome, Plant; D059785:Karyotype; D007621:Karyotyping; D010802:Phylogeny
chemical_list: D018744:DNA, Plant
keywords: Cyperaceae; aneuploidy; cytogenetics; genome evolution; holocentric chromosome; holokinetic drive