Ecologically and economically unvaluable pollinators, bees are an important insect group with more than 20,000 species. Understanding bee distribution dynamics is key to conservation, and with insects declining at alarming rates, research into how bees will respond to global change is crucial.
In this global assessment of bee distribution, researchers compared and combined data from taxonomic treatments, descriptions as well as other undigitized records—with publically available digital occurrence data as mediated by GBIF, BISON, ALA and others.
The comparisson revealed very low digital data coverage and completeness in certain regions, especially Asia, the Middle East and Africa, and subsequently, predicted patterns of richness strongly followed sampling effort.
The overall results identified large hotspots of richness in the southwestern USA, Mediterreanean Basin and Australia, while Israel has the highest richness-per-unit area. Globally, a bimodal gradient creates peaks of richness around 30 degrees latitude in both hemispheres.
Analysis into these patterns revealed 24 variables with significant correlation with richness, including solar radiation and potential evapotranspiration. The highest number of bee species are thus found in areas with high solar insolation, low precipitation (but enough moisture to support plant growth), low wind, more growing degree days and high net primary productivity.