DNA barcoding in Neotropical tadpoles: evaluation of 16S rRNA gene for the identification of anuran larvae from northeastern Brazil

Abstract

The challenge in studying Neotropical tadpoles is identifying species using only their external morphology. However, the DNA barcode protocol is often implemented to help elucidate taxonomic issues. In fact, the identification of frogs through their unknown tadpoles has already been achieved accurately using this protocol. Despite the successful application of this tool, the efficiency of the 16S rRNA gene as a DNA barcode for Neotropical tadpoles has not been fully assessed. Herein we evaluate the efficacy of the 16S rRNA gene for identifying tadpoles from northeastern Brazil. Samples of 100 tadpole specimens from 12 locations were analyzed. The DNA sequences were individually submitted to a BLAST search and were then aligned with a matrix containing available sequences in the GenBank based on the anurans known to occur in the study area. The 16S rRNA fragment successfully identified the analyzed anuran species. Based on DNA barcoding, 8% of the tadpoles morphologically identified at the species level were incorrect. When an incongruence between morphological and molecular identifications was detected, the morphology of the target morphotype was reexamined, and previously neglected morphological characteristics were identified. DNA barcoding using the 16S rRNA gene facilitated the assessment of tadpole richness in northeastern Brazil. This DNA protocol can be used as a starting point for detecting high levels of genetic divergence, highlighting potential taxa that should be studied from phylogenetic and taxonomic perspectives.