Details of characteristics of the 29 virtual species

* Method to generate the virtual species - A virtual species is a group of occurrences, which are selected by an ellipsoid in a 3D environmental space. In this case, we did a principal component analysis (PCA) on the 19 bioclimatic variables, and used the first 3 principal components to create a 3D environmental space. The x, y, z axes are the first three principal components. All of these processes were implemented via Niche Analyst (http://biodiversity-informatics-training.org/software-data-sources/nichea/). Using Niche Analyst, we created two groups of virtual species with different volumes. The volume of ‘big’ group was 143.69, and the ‘small’ one was 2.14. Each group had 7 virtual species with the same centroid and same directions of semi-axes. * The distribution maps of virtual species - Once niches were created, we explored their projections into geographic space, and created different scenarios of abiotic factors in relation to dispersal. Specifically, we created a scenario in which all suitable conditions were accessible (“Hutchinson’s Dream,” or HD), one in which distributional limitation was driven by dispersal/access exclusively and not by abiotic conditions (“Wallace’s Dream,” or WD), and one in which both abiotic and dispersal considerations act to limit distributions in different areas (“Classic BAM,” or CB).