Citogenética do gênero Ancistrus Kner, 1854 (Siluriformes: Loricariidae): revisão bibliográfica de estudos realizados no Brasil

Abstract

The family Loricariidae exhibits high chromosomal diversity and is considered a group of great interest for evolutionary studies in neotropical fishes. Among its representatives, the genus Ancistrus stands out due to its wide distribution, diversity, and significant karyotypic variation. This study aimed to compile and analyze published cytogenetic studies on the genus Ancistrus in Brazil, organizing the available information and understanding the main chromosomal patterns described for the group. A literature review was conducted based on scientific studies available in different databases and search tools, including works involving classical and molecular cytogenetic analyses of the genus. Aspects such as diploid number, karyotypic formula, sex chromosome systems, heterochromatin distribution, nucleolar organizer regions (NORs), and the localization of 18S and 5S ribosomal genes were evaluated. The analyzed studies revealed broad chromosomal diversity within the genus, with variation in diploid number mainly associated with the occurrence of chromosomal rearrangements, such as fusions, as well as the presence of intraspecific polymorphisms. Most studies employ classical cytogenetic approaches, while molecular cytogenetic techniques are mainly used as complementary tools for investigating genome organization and chromosomal evolution. The changes observed in rDNA sites include the disruption of synteny between 18S and 5S sequences. Thus, the compiled data reinforce the importance of the genus as a model for studies on chromosomal evolution and highlight the need to expand integrative analyses involving cytogenetic, molecular, and taxonomic data.