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Published March 31, 2008 | Version v1
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Cytogenetic characterization of Hypostomus nigromaculatus (Siluriformes: Loricariidae)

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Rubert, Marceléia, Zawadzki, Cláudio H., Giuliano-Caetano, Lucia (2008): Cytogenetic characterization of Hypostomus nigromaculatus (Siluriformes: Loricariidae). Neotropical Ichthyology 6 (1): 93, DOI: 10.1590/S1679-62252008000100011, URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252008000100011&lng=en&tlng=en

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urn:lsid:plazi.org:pub:6D6CFFFA551286396E0BFF926937FFB4

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Figure: 10.5281/zenodo.5420256 (DOI)
Figure: 10.5281/zenodo.5420258 (DOI)
Figure: 10.5281/zenodo.5420260 (DOI)
Figure: 10.5281/zenodo.5420262 (DOI)
Figure: 10.5281/zenodo.5420264 (DOI)

References

  • According to Oliveira et al. (1988) and Almeida-Toledo et al. (1993), the migratory rate and population density can influence the karyotypic macrostructure of a group. That is, the greater the mobility and number of individuals of a group, the more stable the karyotypic macrostructure should be, since gene flow is higher and the fixation of some chromosomal alteration would be hindered. Most species of the genus Hypostomus are non-migratory and generally comprise small populations (Britski et al., 1984). Therefore, the differences observed among H. nigromaculatus samples in this study might be related to their populational structure.
  • Based on the results obtained in this work, samples from rio Tibagi basin and rio Mogi-Guacu show considerable cytogenetic differences (FN, Ag-NOR location, and composition and distribution of heterochromatin). These differences corroborate previous reports, showing that this fish group is characterized by non-conserved features in relation to both chromosomal micro- and macrostructure (Michelle et al., 1977; Artoni & Bertollo, 1996).
  • Nevertheless, regarding to external morphology, no apparent differences among the specimens from the three samples studied were observed, or these differences could be very subtle. Therefore, the samples studied could represent either distinct species but morphologically similar (cryptic species), or a single species, morphologically identical, 98 Cytogenetic characterization of Hypostomus nigromaculatus but showing a considerable intra-specific polymorphism. Cytogenetic studies focusing the population structure of Hypostomus species are not available so far. However, Zawadzki et al. (2002) analyzed two samples of H. margaritirer, one from the Itaipu reservoir and another from rio Corumba, a tributary of rio Paranaiba using allozymes. The authors found no diagnostic character but differences in the expected heterozygosity between populations, what they assumed to be due to a non-random mating system.