Article

Chromosome Research

, Volume 8, Issue 7, pp 603-613

First online:

A biodiversity approach in the neotropical Erythrinidae fish, Hoplias malabaricus. Karyotypic survey, geographic distribution of cytotypes and cytotaxonomic considerations

  • Luiz A. C. BertolloAffiliated withDepartamento de Genética e Evolução, Universidade Federal de São Carlos
  • , Guassenir Gonçalves BornAffiliated withDepartamento de Ciências Morfobiológicas, Universidade do Rio Grande
  • , Jorge A. DergamAffiliated withDepartamento de Biologia Animal, Universidade Federal de Viçosa
  • , Alberto Sergio FenocchioAffiliated withDepartamento de Genética, Universidad Nacional de Misiones
  • , Orlando Moreira-FilhoAffiliated withDepartamento de Genética e Evolução, Universidade Federal de São Carlos

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Abstract

Hoplias malabaricus, a widely distributed neotropical freshwater fish, shows a conspicuous karyotypic diversification. An overview of this diversity is presented here comprising several Brazilian populations, and some others from Argentina, Uruguay and Surinam. Seven general cytotypes are clearly identified on the basis of their diploid number (2n=39 to 2n=42), chromosomal morphology and sex chromosome systems, which can be clustered into two major karyotypic groups. This clustering suggests that karyotype structure would be more informative than the diploid number regarding cytotype relationships in this fish group. While some cytotypes show a wide geographical distribution, some others appear to be endemic to specific hydrographic basins. Sympatric cytotypes can occur without detection of hybrid forms; this situation points to a lack of gene flow, a fact that is also reinforced by studies with genomic markers. The karyotypic data support the view that the nominal taxon H. malabaricus corresponds to a species complex comprising distinct evolutionary units, each with well-established chromosomal differences.

cytotaxonomy geographic distribution Hoplias malabaricus fish karyotypic diversity sympatric cytotypes