Estimating range sizes using open access biodiversity data

Study shows that range sizes can be derived accurately from occurrence data for freshwater fish, especially for rare species

Lepisosteus oculatus
Spotted gar (Lepisosteus oculatus) observed in Jackson, Mississippi, USA by amarcianae. Photo via iNaturalist (CC BY-NC 4.0)

When prioritizing conservation efforts, the range size of a species is often used as a measure of rarity and to determine its intrinsic risk of extinction. How ranges are defined or estimated, however, may affect how rare or common a species is seen to be, and whether conservation efforts are justified.

Stream-dwelling organisms, such as freshwater fishes constrained to river networks, may present a particular challenge, and in this study, researchers compared different methods of range size estimation for freshwater species.

Initially selecting a wide taxonomic and geographic representation of species, the authors gathered GBIF-mediated occurrences of 128 fish species in the conterminous United States and calculated range sizes based on minimum convex polygons.

They then compared the GBIF-based results to range sizes derived from NatureServe maps—considered the best available estimates of current distributions—finding strong correlations between the approaches with no detectable taxonomic bias.

Importantly, both analytical approaches consistently identified the rarest and perhaps most vulnerable species, suggesting an important role of open data in filling fundamental knowledge gaps, especially for poorly understood taxa.

Original paper

Smith JA, Benson AL, Chen Y, Yamada SA and Mims MC (2020) The power, potential, and pitfalls of open access biodiversity data in range size assessments: Lessons from the fishes. Ecological Indicators. Elsevier BV 110: 105896. Available at: