Figure 1 . Conceptual illustration of project workflow and niche characterization, using Astragalus alpinus L. (‘alpine milkvetch’; photo in (a )) as an example. (a ) We aggregated georeferenced specimen records from GBIF and iDigBio. Here, GBIF records for A. alpinus are shown in blue. North American mountain ranges are highlighted in grey. These records were then integrated with climate data from WorldClim to build species distribution models (SDMs) using MaxEnt; (b ) SDMs provided a probabilistic view of where we expected species to occur based on their known distributions. In this example, warmer (cooler) colors represent higher (lower) probability ofA. alpinus occurring at that site (this species primarily occurs in and around higher elevation habitat in the Northern Hemisphere). The SDMs were then parsed and analyzed in two different ways, as follows: (c ) We assigned each species a presence/absence rating to each site based on its SDM (requiring at least 5% across at least 25% of the area covered by that site). These presence/ absence matrices allowed us to estimate expected species richness of species in our dataset across different mountain ranges (Fig. 2). (d ) Separately from (c ), we also parsed each SDM by three abiotic variables—temperature, precipitation, and elevation— to build a quantitative, continuously-valued description of each species’ occupied niche space. In this case, the SDM of A. alpinus describes a range centered within montane habitat bounded between -17 and +10 degrees C° and generally below 1000 mm of precipitation. For temperature and precipitation, the horizontal axes in each plot indicate values for the climatic variable and the vertical axis indicates the fraction of the SDM attributable to those values. For elevation, axis orientation is switched; vertical axis represents elevational categories (alpine areas in blues, montane in purples, and foothills or lowland in greens) while the horizontal axis indicates the SDM fraction falling into each category. Thus, the climatic niche of each species was described by three vectors, which jointly describe the weighted proportion of each species range falling within different abiotic conditions.