The environmental and PCS data files contain the output of phylogenetic community structure (PCS) analyses and the average environmental conditions for each spatial scale, taxonomic scale, and community delimitation method combination. Communities were delimited in 6 ways: five km bufferes, ten km buffers, five km grids, ten km grids, fifty km circles, and one hundred km circles. Average environmental conditions were calculated by importing layers from WorldClim into ArcGIS, then calculating the mean for each delimitation method using the Zonal Statistics as Table function. Prefix Geographic area All Commuities from all deserts combined GB Communities from the Great Basin Desert MJ Communities from the Mojave Desert SN Communities from the Sonoran Desert CH Communities from the Chihuahuan Desert Suffix Taxonomic extent n/a Communities composed of all bat taxa Vespertilionidae Communities composed of vespertilionids Myotis Communities composed of Myotis For all files, the following species abbreviations were used: FID = Identification number for each community; assigned by ArcGIS mpd.obs.z = Standardized effect size of mean pairwise distance calculated with the independent swap null model using the appropriate species pool mpd.obs.p = p-value associated with mpd above mntd.obs.z = Standardized effect size of mean nearest taxon distance calculated with the independent swap null model using the appropriate species pool mntd.obs.p = p-value associated with mntd above bio1_MEAN = Average annual mean temperature (WorldClim) for community calulated in ArcGIS bio4_MEAN = Average temperature seasonality (WorldClim) for community calulated in ArcGIS bio12_MEAN = Average annual precipitation (WorldClim) for community calulated in ArcGIS bio15_MEAN = Average precipitation seasonality (WorldClim) for community calulated in ArcGIS