Karyotype Evolution of Talking Thorny Catfishes < b > < i > Anadoras < /i > < /b > (Doradidae, Astrodoradinae): A Process Mediated by Structural Rearrangements and Intense Reorganization of Repetitive DNAs

Anadoras is a thorny catfish genus widespread through the Amazon and Paraguay river basins. It includes 2 nominal species,A. grypus andA. weddellii, plusAnadoras sp. “araguaia,” an undescribed species only recognized morphologically. SinceAnadoras occupies a basal position within the Astrodoradinae phylogeny, it is crucial to identify its cytogenetic features to comprehend the mechanisms involved in the chromosomal diversification of this subfamily. Therefore, we performed a comparative cytogenetic analysis including all species ofAnadoras. Furthermore, we applied a species delimitation analysis based on 600 bp of the mitochondrial cytochrome oxidase subunit 1 (CO1) gene to investigate the taxonomic status of the species. Cytogenetic markers revealed a high degree of similarity amongAnadoras weddellii andAnadoras sp. “araguaia,” both have 2n = 56 chromosomes (24m + 10sm + 22st/a), single NOR sites on acrocentric pair 28, and 5S rDNA sites on submetacentric pair 15.A. grypus has the most divergent chromosomal characteristics because, even though it also has 2n = 56 chromosomes, it exhibits several differences in the chromosome formula, heterochromatin distribution, and number/position of the rDNA sites. In sum, we believe that the chromosome diversification ofAnadoras is due to 4 mechanisms: centric fusion, pericentric/paracentric inversions, nonreciprocal translocations, and activity of transposable elements. Additionally, our phylogenetic tree revealed well-supported...
Source: Cytogenetic and Genome Research - Category: Genetics & Stem Cells Source Type: research