J Syst Evol ›› 2020, Vol. 58 ›› Issue (4): 393-405.DOI: 10.1111/jse.12590

• Research Articles • Previous Articles     Next Articles

Spatial phylogenetics of the North American flora

Brent D. Mishler1,2*, Robert Guralnick3,4, Pamela S. Soltis3,4,5, Stephen A. Smith6, Douglas E. Soltis3,4,5,7, Narayani Barve3, Julie M. Allen8, and Shawn W. Laffan9   

  1. 1University and Jepson Herbaria, University of California, Berkeley, CA 94720‐2465, USA
    2Department of Integrative Biology, University of California, Berkeley, CA 94720‐2465, USA
    3Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA
    4Genetics Institute, University of Florida, Gainesville, FL 32608, USA
    5Biodiversity Institute, University of Florida, Gainesville, FL 32611, USA
    6Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48103, USA
    7Department of Biology, University of Florida, Gainesville, FL 32611, USA
    8Department of Biology, University of Nevada Reno, Reno, NV 89557, USA
    9School of Biological, Earth and Environmental Sciences, The University of New South Wales, Kensington, NSW 2033, Australia
  • Received:2019-03-26 Accepted:2020-04-09 Online:2020-04-15 Published:2020-07-01


North America is a large continent with extensive climatic, geological, soil, and biological diversity. As biota faces threat from habitat destruction and climate change, making a quantitative assessment of biodiversity becomes critically important. Rapid digitization of plant specimen records and accumulation of DNA sequence data enable a much‐needed broad synthesis of species occurrences with phylogenetic data. In this study, the first such synthesis of a flora from such a large and diverse part of the world is attempted, all seed plants from 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. The application of phylogenetic metrics and a randomization test revealed novel results, including a significant phylogenetic clustering across the continent, a striking east–west geographical difference in the distribution of branch lengths, and the discovery of centers of neo‐ and paleoendemism in Mexico, the southwestern USA, and the southeastern USA. Finally, our examination of phylogenetic beta diversity provides a new approach to compare centers of endemism. We discuss the empirical challenges of working at the continental scale and the need for more sampling across large parts of the continent, for both DNA data for terminal taxa and spatial data for poorly understood regions, to confirm and extend these results.

Key words: biodiversity, endemism, North America, phylogenetic diversity, phylogenetic endemism, phylogeny, seed plants