Código de barras de DNA como ferramenta para o estudo da biodiversidade de peixes da família Cichlidae na bacia Amazônica

Abstract

The Neotropical cichlids are a diverse group, which comprises about 60 genera and at least 1300 species are recognized. They are distributed in Central and South America, Texas, West Indies, Africa, Madagascar, Syria, Israel, Iran, Sri Lanka, southern coast of India. The diversity found in the Cichlid family covers the most different morphological and ecological aspects that facilitate the adaptation of this fish family. In addition, evidence based on molecular data showed that most of the diversification of the Neotropical fish fauna occurred recently. These features make it difficult to understand the taxonomy and identification of this fauna, becoming a major challenge for molecular tools. In this context, this study aimed to test the effectiveness of DNA barcode methodology (COI gene) to identify and delineate the diverse ictiofauna of freshwater cichlids in the Neotropics. For this purpose, 59 species of Amazon basin fish were analyzed, being sampled by up to five specimens, morphologically identified beforehand, and 147 DNA barcode sequences obtained. Morphological data were combined with the molecular where only nine species showed agreement in both methods of identification. Of the 45 species analyzed, 40 (88.8%) were correctly identified by the barcode sequencing. The main values of intraspecific and interspecific genetic divergence by K2P in molecular clusters were 0% and 55%. Seven cryptic species (15.5%) as well as seven complexes of species (15.5%) were verified and approximately five species (11.2%) showed absence of mutual monophyly. This study is the first to analyze a large number of freshwater fish species in South America, including a large number of closely related species. The results confirmed the effectiveness of barcode to signal cryptic species and species complexes, which have recently undergone a process of irradiation, in addition to discriminate most species analyzed. The results also revealed genetic differences suggesting reproductive isolation and cryptic speciation in seven species. Finally, the results will contribute significantly for the Life Barcode International Project, and for the FISH-BOL campaign providing sequences of barcodes on the identification of these species by specialists and non-specialists, as well as allowing them to be available for use in other applications.