“Split Happens”: a Rare Case of Chromosomal Mosaicism in Characin from an Impacted River Basin

Abstract

Abstract Chromosomal polymorphisms have been reported in numerous vertebrates, including fishes. Such variation is usually related to karyoevolutionary trends and speciation but might also be a result of environmental stress. Herein, we provide the first karyotype characterization in populations of a widespread small characin (Hemigrammus marginatus) from an impacted river basin in Northeastern Brazil to infer their chromosome organization and putative genotoxic effects. Therefore, we reported intra and interindividual structural polymorphism and multiple active nucleolar organizer regions in samples from Contas River, a highly polluted environment when compared to less impacted areas. Furthermore, this report represents the first description of chromosomal mosaicism in the family Characidae so far. Besides revealing peculiar karyotypic patterns in relation to populations from other basins, our results suggest that the chromosomal instability in specimens H. marginatus might be associated with the presence of xenobiotics in polluted environments.

Keywords

• Chromosomal polymorphism
• environmental stress
• pollution