When taxonomy cries wolf: ancient DNA research must embrace species frameworks to define biodiversity loss through time

Species remain the primary unit for measuring biodiversity in ecology and conservation, and for understanding human-caused extinctions. Historical biodiversity baselines and losses are also increasingly being elucidated by ancient DNA studies. However, these studies often fail to interpret their findings within taxonomic frameworks, resulting in missed opportunities for integrating management-relevant insights about biodiversity loss into modern-day contexts. For example, ancient DNA evidence for extremely recent divergence of the extinct Falkland Islands wolf (Dusicyon australis) and its extinct mainland congener Dusicyon avus is comparable to the timing of divergences between conspecific continental-shelf island and mainland mammal populations rather than species-level differentiation. Extinct Dusicyon populations should therefore be interpreted as conspecific, with important implications for changing paradigms about carnivore extinction risk, the dynamic biogeography of population declines, and the impact of non-native species on island biodiversity. This lack of taxonomic integration might reflect genuine discrepancies between the process and outcomes of ancient DNA research and taxonomic frameworks, but it also reflects a global shortage of trained taxonomists. We encourage studies of historically extinct taxa to align their findings with the units of biodiversity used by modern practitioners.