title: Instability of Multiple Sex Chromosomes Systems in Fish: The Case of Erythrinus erythrinus (Bloch & Schneider, 1801) (Characiformes, Erythrinidae).
abstract: The fish species Erythrinus erythrinus belongs to the family Erythrinidae (order Characiformes, superorder Teleostei) and is considered a species complex because of the considerable differences between the karyotypes of analyzed populations. Whereas some populations present a sex chromosome system with male heterogamety, others do not show differentiated sex chromosomes. In this article, two novel karyotypes of E. erythrinus with the occurrence of male and female heterogamety are described, and a discussion of the stability of multiple sex chromosome systems is provided. A possible cause for sex chromosomes instability is that the Robertsonian rearrangements that originated the multiple systems did not prevent recombination with ancestral chromosomes, which also did not pass through a heterochromatinization process, the opposite of what usually happens with simple systems, especially of the ZZ/ZW or XX/XY type. It is suggested that multiple sex chromosome systems would not act as an effective postzygotic barrier, especially when there are hybridization zones between distinct karyomorphs that bear and that do not bear sex chromosome systems, allowing the generation of hybrids. This finding is important both for the comprehension of sex chromosomes evolution in fish and for conservation biology since the contact between populations with and without multiple sex chromosomes may compromise the regional biodiversity.
authors.affiliation: 1 Universidade Tecnológica Federal do Paraná , Campus Santa Helena, Santa Helena, Brazil .
authors.forename: Vanessa
authors.initials: V
authors.lastname: Bueno
authors.affiliation: 2 Centro de Ciências Biológicas e da Saúde, Universidade Estadual do Oeste do Paraná , Cascavel, Brazil .
authors.forename: Rafaela Maria
authors.initials: RM
authors.lastname: Moresco
authors.affiliation: 2 Centro de Ciências Biológicas e da Saúde, Universidade Estadual do Oeste do Paraná , Cascavel, Brazil .
authors.forename: Jocicléia Thums
authors.initials: JT
authors.lastname: Konerat
authors.affiliation: 3 Departamento de Genética e Evolução, Universidade Federal de São Carlos , São Carlos, Brazil .
authors.forename: Orlando
authors.initials: O
authors.lastname: Moreira-Filho
authors.affiliation: 2 Centro de Ciências Biológicas e da Saúde, Universidade Estadual do Oeste do Paraná , Cascavel, Brazil .
authors.forename: Vladimir Pavan
authors.initials: VP
authors.lastname: Margarido
mesh_terms: D000818:Animals; D005075:Biological Evolution; D060125:Characiformes / Q000235:genetics* / Q000502:physiology*; D020732:Cytogenetic Analysis; D005260:Female; D059785:Karyotype; D008297:Male; D012730:Sex Chromosomes; D019849:Sex Determination Processes