J Syst Evol ›› 2018, Vol. 56 ›› Issue (5): 449-465.DOI: 10.1111/jse.12423

• Research Articles • Previous Articles     Next Articles

The spatial structure of phylogenetic and functional diversity in the United States and Canada: An example using the sedge family (Cyperaceae)

Daniel Spalink1,2*, Jocelyn Pender3, Marcial Escudero4, Andrew L. Hipp5,6, Eric H. Roalson7, Julian R. Starr8, Marcia J. Waterway9, Lynn Bohs1, and Kenneth J. Sytsma2   

  1. 1Department of Biology, University of Utah, 257 1400 E, Salt Lake City, UT 84112, USA
    2Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI 53706, USA
    3Ottawa R&D Centre, Agriculture and Agri-Food Canada, ON, Canada
    4Department of Plant Biology and Ecology, University of Seville, Seville, Spain
    5The Morton Arboretum, 4100 Illinois Route 53, Lisle, IL 60515, USA
    6The Field Museum, 1400 S Lake Shore Dr, Chicago, IL 60605, USA
    7School of Biological Sciences, Washington State University, Pullman, WA 99163, USA
    8Department of Biology, University of Ottawa, Ottawa, Canada
    9Department of Plant Science, Macdonald Campus–McGill University, 21111 Lakeshore, Ste-Anne-de-Bellevue, H9 X 3V9, Canada
  • Received:2017-12-01 Accepted:2018-05-03 Published:2018-09-27

Abstract: Systematically quantifying diversity across landscapes is necessary to understand how clade history and ecological heterogeneity contribute to the origin, distribution, and maintenance of biodiversity. Here, we chart the spatial structure of diversity among all species in the sedge family (Cyperaceae) throughout the USA and Canada. We first identify areas of remarkable species richness, phylogenetic diversity, and functional trait diversity, and highlight regions of conservation priority. We then test predictions about the spatial structure of this diversity based on the historical biogeography of the family. Incorporating a phylogeny, over 400 000 herbarium records, and a database of functional traits mined from online floras, we find that species richness and functional trait diversity peak in the Northeastern USA, while phylogenetic diversity peaks along the Gulf of Mexico. Floristic turnover among assemblages increases significantly with distance, but phylogenetic turnover is twice as rapid along latitudinal gradients as along longitudinal gradients. These patterns reflect the expected distribution of Cyperaceae, which originated in the tropics but radiated in temperate regions. We identify assemblages with an abundance of rare, range‐restricted lineages, and assemblages composed of species generally lacking from diverse regions. We argue that both of these metrics are useful for developing targeted conservation strategies. We use the data generated here to establish future research priorities, including the testing of a series of hypotheses regarding the distribution of chromosome numbers, photosynthetic pathways, and resource partitioning in sedges.

Key words: beta-diversity, biogeography, C4photosynthesis, CANAPE, chromosome number, functional diversity, herbarium data, phylogenetic bet-diversity, phylogenetic diversity