Vertebrate diversity revealed by metabarcoding of bulk arthropod samples from tropical forests

Background Thousands of bulk arthropod samples are collected globally every year for monitoring programs, conservation efforts, and ecosystem assessments. The taxonomic contents of these samples can be assessed either morphologically or molecularly using DNA metabarcoding coupled with high‐throughput sequencing, the latter of which has gained popularity in recent years. In a related field, only vertebrateingesting invertebrates, such as carrion flies and blood‐feeding leeches, are targeted for collection, and metabarcoding is carried out on the vertebrate DNA in their gut contents to provide information on vertebrate diversity (invertebrate‐derived DNA, iDNA). Aims Here, we show that the two approaches can be combined, that is, that vertebrate DNA can be detected through metabarcoding of bulk arthropod samples. Materials and Methods: Two metabarcoding primer sets were used to PCR amplify mammal and vertebrate DNA in DNA extracted from bulk arthropod samples collected with pitfall and Malaise traps in tropical forests in Brazil and Tanzania. Results In total, 32 vertebrate taxa were detected representing mammals, amphibians, and birds. Detected taxa were within, or close to, their known geographical distributions. Conclusion This study demonstrates that with a relatively small additional investment, information on vertebrate diversity can be obtained from bulk arthropod samples. This is of particular interest in projects where bulk arthropod samples are collected and extracted with the aim to use metabarcoding to assess arthropod taxa. In such studies, the additional information on vertebrates can further inform ecological assessments and monitoring programs and function as a supplement to traditional survey methods of vertebrates.