title: Population divergence and peculiar  karyoevolutionary trends in the  loricariid fish Hypostomus aff. unae  from northeastern Brazil.
abstract: Loricariidae  (Siluriformes, Hypostominae) is one of the most diverse catfish families. In  spite of the wide distribution of loricariids in South America, cytogenetic  reports are available for only a few species, mostly from southern and  southeastern Brazil. We made the first chromosomal analysis of Hypostomus aff. unae from the Contas River basin in northeastern Brazil. Four  populations isolated by short distances but from distinct landscapes were  studied based on conventional staining, C-banding, argyrophilic nucleolar  organizer regions (Ag-NOR), CMA(3)/DAPI fluorochrome staining, and fluorescent in  situ hybridization with 18S rDNA probes. Although sharing the same diploid  number (2n = 76) and NOR locations, each population presented exclusive  karyotype formulae and specific patterns of heterochromatic and AT-rich  regions. The derived karyotypes of H. aff. unae (2n >54; high  number of acrocentrics bearing AT-rich interstitial heterochromatin) indicated  a divergent karyoevolution, mostly driven by centric fissions, pericentric  inversions and particular heterochromatin dispersion models. This finding of  distinct evolutionary units in H. aff. unae will be useful for  understanding the natural history of loricariids from relatively unexplored  coastal basins in South America.
authors.affiliation: Departamento de Biologia Geral, Universidade Estadual de Londrina, PR, Brasil.
authors.forename: J A
authors.initials: JA
authors.lastname: Bitencourt
authors.forename: P R A M
authors.initials: PR
authors.lastname: Affonso
authors.forename: L
authors.initials: L
authors.lastname: Giuliano-Caetano
authors.forename: P L S
authors.initials: PL
authors.lastname: Carneiro
authors.forename: A L
authors.initials: AL
authors.lastname: Dias
mesh_terms: D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D019143:Evolution, Molecular; D005399:Fishes / Q000235:genetics*; D014644:Genetic Variation; D007621:Karyotyping
chemical_list: D017931:DNA Primers