Astyanax altiparanae

description

The karyotypic data obtained from both populations indicate a conservativeness in diploid number. Similar to previous cytogenetic studies in Astyanax altiparanae (Fernandes & Martins-Santos, 2004), the present report also verified a diploid number of 50 chromosomes for these two populations. Thus, this feature should be considered primitive for this species and very relevant for the polarization of karyotypic data in phylogenetic comparisons within the genus Astyanax. No chromosomal heteromorphism concerning sex differentiation has been foundiin any population analyzed so far. On the other hand, the karyotypic formula and the fundamental number of both populations showed a disruption of the main evolutionary conservativeness. Inter-populational karyotypic differences related to chromosomal morphology, especially concerning submetacentric and acrocentric chromosomes, could be observed in the populations from the upper rio Tibagi and upper rio Iguaçu, with a fundamental number equal to 92 and 94, respectively. Therefore, the role of nonrobertsonian events in karyotypic diversification, such as inversions (especially pericentric ones) could be discussed in the karyotypic evolution of

Cytogenetic and comparative morphology of two allopatric populations of Astyanax altiparanae Garutti & Britski, 2000 (Teleostei: Characidae) from upper rio Paraná basin