Taxonomic uncertainty: causes, consequences, and metrics

Taxonomic uncertainty is prevalent across many biological groups. Yet it remains overlooked in ecology, evolution, and conservation research, leading to potential misinterpretations of biodiversity patterns. Here, we synthesize the recent literature to define taxonomic uncertainty, examine its root causes and consequences, and present key metrics for its quantification. We argue that species should not be assumed to be equivalent units in biodiversity research. To address this challenge, researchers must (i) identify taxa with uncertain boundaries, (ii) track changes in species taxonomy, and (iii) incorporate taxonomic uncertainty into macroecological studies and conservation assessments. These tasks open new research opportunities involving close collaboration among ecologists, evolutionary biologists, taxonomists, and systematists. Integrating taxonomic uncertainty into biodiversity research will improve the robustness of ecological models and conservation strategies, ultimately leading to a more accurate understanding of biodiversity.