The effect of scale on occurrence-based characterization of species’ environmental niches

Background/Question/Methods

The measurement, quantification, and comparison of species’ realized environmental niches have informed a diverse array of analyses such as niche conservatism, biogeographic analysis, biological invasions, and species distribution models. At the core of these analyses is a characterization of the environmental conditions where a species is present or absent. Here we explore how the outcome of this characterization depends on the spatial and temporal grain of the environmental dataset. We evaluate the scale-dependence of niche characterization in neo-tropical bird species using several niche quantification metrics and new environmental annotation tools implemented in the Map of Life infrastructure. 

Results/Conclusions

We find that scale-dependence exists for many but not all species. Niche characterization varies strongly with spatial and temporal grain for habitat specialists, high-elevation species, and species with small geographic ranges, and does not vary or varies weakly for generalist species or for species with large geographic ranges. Based on these results we provide guidelines on how to evaluate potential limitations of occurrence-based niche characterizations.