An uncommon condition for a sex chromosome system in Characidae fish. Distribution and differentiation of the ZZ/ZW system in Triportheus |
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Authors: | Roberto Ferreira Artoni José Das Neves Falcão Orlando Moreira-Filho Luiz Antonio Carlos Bertollo |
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Institution: | (1) Departamento de Biologia Geral, Universidade Estadual de Ponta Grossa, Campos de Uvaranas, 84030-000 Ponta Grossa, PR, Brazil;(2) Departamento de Biologia-ICB, Universidade do Amazonas, 69077-000 Manaus, AM, Brazil;(3) Departamento de Genética e Evolução, Universidade Federal de São Carlos, Caixa Postal 676, 13565-905 São Carlos, SP, Brazil |
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Abstract: | Triportheus is a neotropical freshwater Characidae fish that has a well-differentiated ZZ/ZW sex chromosome system. The W chromosome of this genus contains a large amount of heterochromatin and is smaller than the Z chromosome. This contrasts with other ZW fish systems where the W chromosome is larger in size due to increased heterochromatin. All species of Triportheus that have been studied cytologically (about 50% of the known species for this genus, from some of the major South American hydrographic basins) share this sex chromosome system, indicating a probable synapomorphic condition not present in other genera of the large Characidae family. However, while the Z chromosome appears to be largely conserved, the W chromosome shows a differential evolution with morphological differentiations not only among species, but also among populations from the same hydrographic basin, and with some species presenting a greater homology between the W and the Z chromosomes than others. |
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Keywords: | geographic distribution sex chromosome differentiation Triportheus fish |
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