Old uses, new species: the hidden effects of taxonomic change on ethnobiological knowledge

Much of the ethnobiological knowledge produced by research is documented and synthesized under scientific names, yet species boundaries can change long after records are produced. When a historically broadly circumscribed species is later split, earlier information on use, hunting, trade, management, or other human relationships may no longer contain enough evidence to determine which currently recognized species was involved. We introduce taxonomic erosion of ethnobiological knowledge as the loss of contemporary taxonomic resolution or assignability of previously documented ethnobiological records following changes in taxonomic circumscription. We distinguish this process from nomenclatural change, misidentification, and what has been termed erosion of local ecological knowledge, which concerns the knowledge held by people rather than its scientific documentation. Its occurrence depends jointly on the nature of taxonomic change and on the evidence preserved with each record, including voucher specimens, diagnostic images, biological material, provenance, and other verifiable documentation. We also introduce the complementary concept of taxonomic recovery of ethnobiological knowledge, which occurs when preserved evidence allows historical records to be reconnected to currently recognized taxa. Newly described or newly delimited species may also possess histories of human relationships that long predate their scientific recognition. We argue that taxonomic traceability should be treated as a core component of ethnobiological documentation, databases, and syntheses. The taxonomic resolution assigned to a record should never exceed that supported by the preserved evidence.