title: Karyotype diversity and genome size variation in Neotropical Maxillariinae orchids.
abstract: Orchidaceae is a widely distributed plant family with very diverse vegetative and floral morphology, and such variability is also reflected in their karyotypes. However, since only a low proportion of Orchidaceae has been analysed for chromosome data, greater diversity may await to be unveiled. Here we analyse both genome size (GS) and karyotype in two subtribes recently included in the broadened Maxillariinea to detect how much chromosome and GS variation there is in these groups and to evaluate which genome rearrangements are involved in the species evolution. To do so, the GS (14 species), the karyotype - based on chromosome number, heterochromatic banding and 5S and 45S rDNA localisation (18 species) - was characterised and analysed along with published data using phylogenetic approaches. The GS presented a high phylogenetic correlation and it was related to morphological groups in Bifrenaria (larger plants - higher GS). The two largest GS found among genera were caused by different mechanisms: polyploidy in Bifrenaria tyrianthina and accumulation of repetitive DNA in Scuticaria hadwenii. The chromosome number variability was caused mainly through descending dysploidy, and x=20 was estimated as the base chromosome number. Combining GS and karyotype data with molecular phylogeny, our data provide a more complete scenario of the karyotype evolution in Maxillariinae orchids, allowing us to suggest, besides dysploidy, that inversions and transposable elements as two mechanisms involved in the karyotype evolution. Such karyotype modifications could be associated with niche changes that occurred during species evolution.
authors.affiliation: Departamento de Biologia Vegetal, Instituto de Biociências, Universidade Estadual de Campinas, Campinas, Brazil.|Departamento de Genética, Instituto de Biociências, Universidade Estadual Paulista Julio de Mesquita Filho, Botucatu, Brazil.|Instituto de Ciências e Tecnologia, Universidade Federal de São Paulo, São José dos Campos, Brazil.
authors.forename: A P
authors.identifier: http://orcid.org/0000-0002-9878-3925
authors.initials: AP
authors.lastname: Moraes
authors.affiliation: Departamento de Biologia Vegetal, Instituto de Biociências, Universidade Estadual de Campinas, Campinas, Brazil.
authors.forename: S
authors.initials: S
authors.lastname: Koehler
authors.affiliation: Departamento de Botânica, Centro de Ciências Biológicas, Cidade Universitária, Universidade Federal de Pernambuco, Recife, Brazil.|Synthesis Centre, German Centre for Integrative Biodiversity Research, Leipzig, Germany.|Center for Computational and Theoretical Biology, Ecosystem Modeling, University of Würzburg, Würzburg, Germany.
authors.forename: J S
authors.initials: JS
authors.lastname: Cabral
authors.affiliation: Departamento de Biologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Juiz de Fora, Brazil.
authors.forename: S S L
authors.initials: SS
authors.lastname: Gomes
authors.affiliation: Departamento de Biologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Juiz de Fora, Brazil.
authors.forename: L F
authors.initials: LF
authors.lastname: Viccini
authors.affiliation: Instituto de Botânica, Núcleo de Pesquisa Orquidário do Estado de São Paulo, São Paulo, Brazil.
authors.forename: F
authors.initials: F
authors.lastname: Barros
authors.affiliation: Departamento de Ciências Biológicas, Centro de Ciências Agrárias, Universidade Federal da Paraíba, Rodovia, Areias, Brazil.
authors.forename: L P
authors.initials: LP
authors.lastname: Felix
authors.affiliation: Departamento de Botânica, Centro de Ciências Biológicas, Cidade Universitária, Universidade Federal de Pernambuco, Recife, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Guerra
authors.affiliation: Departamento de Biologia Vegetal, Instituto de Biociências, Universidade Estadual de Campinas, Campinas, Brazil.
authors.forename: E R
authors.initials: ER
authors.lastname: Forni-Martins
mesh_terms: D007446:Chromosome Inversion / Q000235:genetics; D032461:Chromosomes, Plant / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D019143:Evolution, Molecular; D014644:Genetic Variation; D059646:Genome Size; D018745:Genome, Plant / Q000235:genetics*; D059785:Karyotype; D029595:Orchidaceae / Q000235:genetics*; D010802:Phylogeny; D011123:Polyploidy
chemical_list: D018744:DNA, Plant; D004275:DNA, Ribosomal
keywords: 
  Bifrenaria
  ; 
  Lycaste
  ; 
  Rudolfiella
  ; 
  Xylobium
  ; 
  rDNA
  ; chromosome evolution; chromosome inversion; dysploidy