title: Do chromosome numbers reflect phylogeny? New counts for Bombacoideae and a review of Malvaceae s.l.
abstract: •
  
  
  OBJECTIVE
  Whole genome duplication (WGD) and specific polyploidy events marked turning points for angiosperm genome structure and evolution. Therefore, cytogenetic studies of polyploidy-prone groups such as the tropical Malvaceae and plant formations such as as the Brazilian Cerrado have gained further importance. We present new chromosome counts for Cerrado Bombacoideae and revised chromosome numbers for the Malvaceae s.l., compare these between subfamilies, and relate them to phylogenetic signal.•
  
  
  METHODS
  We studied the chromosome number of Eriotheca candolleana, E. gracilipes, E. pubescens, Pachira glabra, Pseudobombax longiflorum, and P. tomentosum. We also compared Eriotheca species ploidy levels using flow cytometry. We compiled chromosome numbers for 557 species of Malvaceae s.l., including 37 Bombacoideae species. We included this information in a phylogenetic reconstruction based on chloroplast matK-trnK DNA to evaluate chromosome evolution of the Malvaceae s.l. and the Bombacoideae in particular.•
  
  
  RESULTS
  The Cerrado Bombacoideae presented consistently high chromosome numbers. Numbers for Eriotheca species were among the highest and varied among populations. Flow cytometry analyses showed similar 1Cx DNA for all cytotypes and indicated neopolyploidy. Chromosome numbers differed between subfamilies, with the lowest numbers in the Malvoideae and Byttnerioideae and the highest in Tilioideae. Chromosome numbers had significant phylogenetic signal for Bombacoideae but not for Malvoideae or Malvaceae s.l.•
  
  
  CONCLUSIONS
  Clearly distinct chromosome numbers allied to monophyly provide some support for a circumscription of the Bombacoideae and distinction within the Malvaceae. The phylogenetic signal for chromosome number supports the idea of an ancient WGD and further neopolyploidy events as important evolutionary trends for the Bombacoideae.
authors.affiliation: Instituto de Genética e Bioquímica, Universidade Federal de Uberlândia, Uberlândia-MG 38400-902, Brazil.
authors.forename: Rafaela C
authors.initials: RC
authors.lastname: Marinho
authors.affiliation: Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia-MG 38400-902, Brazil.
authors.forename: Clesnan
authors.initials: C
authors.lastname: Mendes-Rodrigues
authors.affiliation: Departamento de Biología Vegetal y Ecología; Universidad de Sevilla; Apdo. 1095, E-41080 Sevilla, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Balao
authors.affiliation: Departamento de Biología Vegetal y Ecología; Universidad de Sevilla; Apdo. 1095, E-41080 Sevilla, Spain.
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Ortiz
authors.affiliation: Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia-MG 38400-902, Brazil.
authors.forename: Júlia
authors.initials: J
authors.lastname: Yamagishi-Costa
authors.affiliation: Instituto de Genética e Bioquímica, Universidade Federal de Uberlândia, Uberlândia-MG 38400-902, Brazil.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Bonetti
authors.affiliation: Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia-MG 38400-902, Brazil.
authors.forename: Paulo E
authors.initials: PE
authors.lastname: Oliveira
mesh_terms: D005075:Biological Evolution; D001938:Brazil; D032461:Chromosomes, Plant; D018742:DNA, Chloroplast / Q000032:analysis; D019660:Malvaceae / Q000235:genetics*; D010802:Phylogeny; D011123:Polyploidy
chemical_list: D018742:DNA, Chloroplast
keywords: Bombacoideae; Cerrado; Eriotheca; Malvaceae; chromosome number; phylogeny; polyploidy