Taxonomic uncertainty: causes, consequences, and metrics

Taxonomic uncertainty is prevalent across many biological groups. Yet, it remains overlooked in ecology, evolution, and conservation, leading to potential misinterpretations of biodiversity patterns. Here, we argue that this uncertainty emerges from the interaction between biological processes shaping natural lineages and human efforts to name and classify them. Based on this, we propose a set of metrics to quantify confidence in species boundaries and to track the history of taxonomic change and stability. We show how these metrics can be embedded into biodiversity analyses, from mapping uncertainty across taxa and geographic regions to assigning weights to species and deriving more realistic error ranges in ecological models. Making taxonomic uncertainty explicit advances biodiversity science and strengthens conservation decisions.