Conhecer para conservar: acessando a diversidade genética, com DNA barcode, na ictiofauna do Rio São Francisco

Abstract

Located in South America, São Francisco River (SFR) is distributed from the Southeast to the Brazil Northeast, is the 27th largest river in the world. This watershed is known for its diversity and endemism, with its ichthyofauna containing records of 178 species (60% endemic), but due to anthropic factors there are species that have come to be considered vulnerable, endangered and critically endangered. There are gaps in knowledge about the SFR, so that genetic knowledge is still diffuse and incipient in the submiddle (dams) and lower (silted) stretches. In this context, the present study aimed to overcome knowledge of biodiversity deficits, as well as to evaluate the SFR ichthyofauna genetic diversity, applying DNA barcode techniques. We evaluated 90 species, 74 genera, 28 families and 6 orders, including Characiformes (40 species), Cyprinodontiformes (6 species), Gymnotiformes (3 species), Perciformes (4 species), Siluriformes (36 species) and the Synbranchiformes (1 species). Distinct genetic divergence (GD) patterns were identified: GD<1% (74 species or 82.22%), 1%2% (8 species or 8.89%). Furthermore, identification errors involving three species pairs were detected: Cetopsorhamdia iheringi and Phenacorhamdia tenebrosa; Imparfinis mirini and I. minutus; Characidium fasciatum and C. gomesi. Some cases of species complexes and taxonomic warnings involving the genera Astyanax and Psalidodon were also found. Deep genetic divergence was also verified for the species Pimelodella vittata, Synbranchus marmoratus, Rhamdia quelen, Piabina argentea, Gymnotus carapo, Hyphessobrycon santae and Pamphorichthys hollandi. Such results help to understand the SFR ichthyofauna systematics and evolution, considering its hydrogeological formation. It is expected that the knowledge generated here will be used in the elaboration and updating of management and conservation plans for the ichthyofauna of the SFR.