Comparative study reveals high discordance in species delimitation among expert taxonomists analyzing identical fish data, indicating substantial subjectivity in biodiversity estimates.
Key Points
To evaluate the precision and reproducibility of species delimitation among independent taxonomic experts evaluating identical morphological and molecular datasets.
Provided identical morphological and genetic datasets representing four Neotropical freshwater fish genera to 40 taxonomic experts (10 per genus).
Assessed delimitation consistency under two experimental conditions: using experts' preferred analytical methods and using standardized analytical outputs.
Partitioned variance into analytical versus interpretative components and tested whether seven expert attributes explained deviations from modal species estimates.
Total discordance in species delimitation across experts was 35.0% under preferred analytical pipelines.
Standardizing analytical outputs reduced variation, but a substantial 23.5% discordance persisted strictly due to interpretative differences among experts.
None of the seven evaluated expert attributes—including years of experience, publication record, geographic location, or taxonomic concepts—explained deviations from modal species counts.