Spatial phylogenetics of the North American flora

North America is a large continent with extensive climatic, geological, soil, and biological diversity. That biota is under threat from habitat destruction and climate change, making a quantitative assessment of biodiversity of critical importance. Rapid digitization of plant specimen records and accumulation of DNA sequence data enable a much-needed broad synthesis of species occurrences with phylogenetic data. Here we attempted the first such synthesis of a flora from such a large and diverse part of the world: all seed plants for the North American continent (here defined to include Canada, United States, and Mexico) with a focus on examining phylogenetic diversity and endemism. We collected digitized plant specimen records and chose a coarse grain for analysis, recognizing that this grain is currently necessary for reasonable completeness per sampling unit. We found that raw richness and endemism patterns largely support previous hypotheses of biodiversity hotspots. Application of p...