Cataloging the world’s plant diversity is an ongoing challenge, and because of accelerated anthropogenic extinctions, the rapid documentation of biodiversity is more critical than ever. Just over a decade ago, DNA barcodes were proposed as an alternative to morphological approaches for species identification. Although DNA barcodes have proved to be successful for most organisms, these have failed to discriminate within many species-rich genera of plants. Here, we examine how chemical fingerprinting, or chemocoding, may be particularly helpful in distinguishing confusing or closely related species in the species-rich and recently radiated Neotropical genus of trees Inga Mill. (Leguminosae, Mimosoideae).
Results/Conclusions
Using untargeted metabolomics in combination with multivariate analysis to characterize small defense-related chemical markers, we constructed phytochemical, species-level fingerprints, which we define as chemocoding. Specifically, we compared the effectiveness of conventional DNA barcoding, next generation sequencing, and chemocoding to discriminate among closely related species of Inga within a single site and between sites. Our results show that chemocoding is faster and more efficient and effective than DNA-based species discrimination methods.
Given that the species is the fundamental unit of analysis for conservation, biodiversity assessment, and for understanding ecological and evolutionary processes, the development of accurate identification methods is essential. Moreover, even after species have been designated, distinct species may not differ morphologically such that correct identification in the field may require a cheap, fast method that will permit confirmation for every plant. We suggest that chemocoding is a valuable tool for distinguishing confusing species, particularly in the diverse tropics where many species-rich genera do not resolve with DNA barcoding.