Diversificação citogenômica em serranidae (Perciformes), um modelo de estase cariotípica: aspectos evolutivos e aplicados

Abstract

The Serranidae family, whose representatives are known as groupers, is one of the most diverse groups of fish in reef environments. They are efficient predators that can occupy everywhere from tide pools to deep reefs. Some species can reach considerable size and, in general, significant economic value. With a circunglobal distribution, the group consists of 577 species, distributed in 75 genera, of which Epinephelus is the most representative. Despite the growing set of genetic information, less than 10% of species have known cytogenetic aspects. Cytogenetic approaches to the family are dissociated in terms of their phylogenetic, geographical and taxonomic aspects, limiting the understanding of their evolutionary aspects and applied to management. Conventional cytogenetic analyzes and fluorescent in situ hybridization mapping of the 18S rDNA, 5S rDNA sequences, transposable elements Tol2 and Rex3, microsatellites (CA)15, (GA)15, (CAA)10 and (CGG)10, were performed in 11 species of Serranidae. The first chapter aims to compare the distribution of repetitive sequences within the phylogenetic scenario and in different biogeographic regions. Because the cytogenetic information is concentrated in the genus Epinephelus, the second chapter provides cytogenomic information for three other species in the family of the genera Cephalopholis and Rypticus. In the third chapter, cytogenomic analyzes of three species of groupers of commercial interest were performed to generate information on the organization of chromosomes and the level of chromosomal divergence between species, in addition to adaptive aspects and potentialities applicable to interspecific hybridization practices. All species presented 2n = 48, of which only three have karyotypes not composed exclusively of acrocentric elements. Karyotype conservatism, only disturbed by pericentric inversions, extends to the organization of repetitive DNA where the repetitive sequences analyzed here reflect a low evolutionary dynamism. The cytogenetic and genomic divergence between species due to common ancestry that occurred in periods from 15 to 11 M.a apparently provides a reduced level of post-zygotic reproductive block, with valuable implications for the hybridization induced in aquaculture. From a biogeographic and phylogenetic perspective, the most basal groups in the Atlantic Ocean demonstrate 2n = 48a as the ancestral pattern for the family, indicating that speciation in the group was not followed by significant karyotype changes and despite a relative frequency of divergent karyotypes, this group of fish is adapted to an evolutionary pattern of karyotype stasis.