title: Highly conserved Z and molecularly diverged W chromosomes in the fish genus Triportheus (Characiformes, Triportheidae).
abstract: The main objectives of this study were to test: (1) whether the W-chromosome differentiation matches to species' evolutionary divergence (phylogenetic concordance) and (2) whether sex chromosomes share a common ancestor within a congeneric group. The monophyletic genus Triportheus (Characiformes, Triportheidae) was the model group for this study. All species in this genus so far analyzed have ZW sex chromosome system, where the Z is always the largest chromosome of the karyotype, whereas the W chromosome is highly variable ranging from almost homomorphic to highly heteromorphic. We applied conventional and molecular cytogenetic approaches including C-banding, ribosomal DNA mapping, comparative genomic hybridization (CGH) and cross-species whole chromosome painting (WCP) to test our questions. We developed Z- and W-chromosome paints from T. auritus for cross-species WCP and performed CGH in a representative species (T. signatus) to decipher level of homologies and rates of differentiation of W chromosomes. Our study revealed that the ZW sex chromosome system had a common origin, showing highly conserved Z chromosomes and remarkably divergent W chromosomes. Notably, the W chromosomes have evolved to different shapes and sequence contents within ~15-25 Myr of divergence time. Such differentiation highlights a dynamic process of W-chromosome evolution within congeneric species of Triportheus.
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil.
authors.forename: C F
authors.initials: CF
authors.lastname: Yano
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil.
authors.forename: L A C
authors.initials: LA
authors.lastname: Bertollo
authors.affiliation: Institute for Applied Ecology, University of Canberra, Canberra, Australian Capital Territory, Australia.
authors.forename: T
authors.initials: T
authors.lastname: Ezaz
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia.
authors.forename: V
authors.initials: V
authors.lastname: Trifonov
authors.affiliation: Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov, Czech Republic.
authors.forename: A
authors.initials: A
authors.lastname: Sember
authors.affiliation: Jena University Hospital, Friedrich Schiller University, Institute of Human Genetics, Jena, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Liehr
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil.
authors.forename: M B
authors.initials: MB
authors.lastname: Cioffi
mesh_terms: D000818:Animals; D005075:Biological Evolution; D060126:Characidae / Q000235:genetics*; D002874:Chromosome Mapping; D020223:Chromosome Painting; D055028:Comparative Genomic Hybridization; D004275:DNA, Ribosomal / Q000235:genetics; D005260:Female; D006570:Heterochromatin / Q000235:genetics; D008297:Male; D010802:Phylogeny; D012730:Sex Chromosomes; D013045:Species Specificity
chemical_list: D004275:DNA, Ribosomal; D006570:Heterochromatin