6 LUNDELLIA DECEMBER, 2016 MOLECULAR PHYLOGENY OF PECTIS (TAGETEAE,ASTERACEAE), A C4 GENUS OF THE NEOTROPICS, AND ITS SISTER GENUS POROPHYLLUM Debra R. Hansen,1 Robert K. Jansen,1 Rowan F. Sage,2 Jose´ Luis Villasen˜or,3 and Beryl B. Simpson1 1Department of Integrative Biology, The University of Texas at Austin, 205 West 24th Street, Austin, Texas 78712, USA, email:
[email protected] 2Department of Ecology & Evolutionary Biology, University of Toronto, 25 Willcocks Street, Room 3055, Toronto, Ontario, Canada M5S 3B2 3Departamento de Bota´nica, Instituto de Biologı´a, Universidad Nacional Auto´noma de Me´xico, Apartado Postal 70-233, 04510 Me´xico, D.F. Mexico Abstract: Pectis is a genus of 690 xeric adapted New World species. Previous molecular phylogenetic studies showed Pectis closely related to Porophyllum, and one analysis resolved Porophyllum species nested within Pectis. Some Pectis species are known to use C4 photosynthesis. Here we investigate the phylogeny of Pectis and Porophyllum, examine the ploidy levels and geographical distribution of Pectis species in light of its phylogeny, and infer the origin and extent of C4 photosynthesis in both genera. Chloroplast and ITS data from 78 Pectis and 22 Porophyllum species were used to test the monophyly of Pectis and its previously described sections. Carbon isotope data were obtained to infer the photosynthetic pathway of 80 species, and the results mapped on the inferred phylogenies to determine the timing and pattern of evolution of the C4 pathway. The ITS dataset supports a monophyletic Pectis sister to a monophyletic Porophyllum, while the chloroplast dataset places two Porophyllum species sister to a combined Pectis+Porophyllum clade.