Barcoding Brazilian mammals to monitor biological diversity and threats: trends, perspectives, and knowledge gaps

DNA barcoding and environmental DNA (eDNA) represent an important advance for biomonitoring the world's biodiversity and its threats. However, these methods are highly dependent on the presence of species sequences on molecular databases. Brazil is one of the largest and most biologically diverse countries in the world. However, many knowledge gaps still exist for the description, identification, and monitoring of its mammalian biodiversity using molecular methods. We aimed at unraveling the patterns related to the presence of Brazilian mammal species on molecular databases to improve our understanding on how effectively it would be to monitor them using DNA barcoding and environmental DNA, and contribute to the conservation of this flagship zoological group. We found that many gaps exist in molecular databases, with many taxa being poorly represented, particularly from the Amazon biome, the order Lagomorpha, and arboreal, gomivorous, near extinct, and illegally traded species. Moreover, our analyses revealed that the year of species description was the most important factor determining the probability of a species to have been sequenced. Primates are the group with the highest number of species considered to be priority for sequencing due to their high level of combined threats. We highlight where investments are needed to fill knowledge gaps and increase the representativity of species on molecular databases to enable a better monitoring ability of Brazilian mammals encompassing different traits using DNA barcoding and environmental DNA.