title: Cryptic Chromosomal Diversity in the Complex "Geophagus" brasiliensis (Perciformes, Cichlidae).
abstract: Among American cichlids, Geophagus stands out as a species-rich genus widespread over neotropical region. Despite their diversity and confusing taxonomy, only few and basic chromosomal reports are available in populations/species along Atlantic coast, hindering our understanding about evolutionary trends in this genus. Therefore, detailed chromosomal studies were performed in "Geophagus" brasiliensis complex from coastal rivers in northeastern Brazil, totalizing seven populations of Geophagus brasiliensis and one of Geophagus itapicuruensis. All samples shared a diploid number (2n) of 48 divided into 2 submetacentric and 46 subtelocentric/acrocentric chromosomes with (peri)centromeric heterochromatin, hypothesized as a symplesiomorphy for Geophagini. Although G. itapicuruensis and two populations of G. brasiliensis presented single NORs on short arms, multiple GC-rich rDNA sites were observed in the remaining G. brasiliensis samples, ranging from three to six NOR-bearing chromosomes. Inversely, 5S rDNA sites were invariably located at interstitial region on a st/a pair, nonsyntenic to NORs. A compilation of the data set in Geophagus shows that their chromosomal evolution has been driven by pericentric inversions and microstructural changes. Besides, the divergence found in northeastern Brazil places this region as a biodiversity hotspot. A taxonomic revision in the complex "Geophagus" brasiliensis is recommended with the support of cytogenetic analyses.
authors.affiliation: 1 Departamento de Ciências Biológicas, Laboratório de Citogenética, Universidade Estadual do Sudoeste da Bahia , Jequié, Bahia, Brazil .
authors.forename: Isabel Araújo
authors.initials: IA
authors.lastname: Oliveira
authors.affiliation: 1 Departamento de Ciências Biológicas, Laboratório de Citogenética, Universidade Estadual do Sudoeste da Bahia , Jequié, Bahia, Brazil .
authors.forename: Leandro Araújo
authors.initials: LA
authors.lastname: Argolo
authors.affiliation: 1 Departamento de Ciências Biológicas, Laboratório de Citogenética, Universidade Estadual do Sudoeste da Bahia , Jequié, Bahia, Brazil .
authors.forename: Jamille de Araújo
authors.initials: Jde A
authors.lastname: Bitencourt
authors.affiliation: 1 Departamento de Ciências Biológicas, Laboratório de Citogenética, Universidade Estadual do Sudoeste da Bahia , Jequié, Bahia, Brazil .
authors.forename: Débora
authors.initials: D
authors.lastname: Diniz
authors.affiliation: 2 Departamento de Biologia Estrutural, Molecular e Genética, Universidade Estadual de Ponta Grossa , Ponta Grossa, Paraná, Brazil .
authors.forename: Marcelo Ricardo
authors.initials: MR
authors.lastname: Vicari
authors.affiliation: 1 Departamento de Ciências Biológicas, Laboratório de Citogenética, Universidade Estadual do Sudoeste da Bahia , Jequié, Bahia, Brazil .
authors.forename: Paulo Roberto Antunes de Mello
authors.initials: PR
authors.lastname: Affonso
mesh_terms: D000818:Animals; D002875:Chromosomes / Q000235:genetics*; D023681:Cichlids / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics; D014644:Genetic Variation; D010802:Phylogeny; D013045:Species Specificity
chemical_list: D004275:DNA, Ribosomal