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Abstract Detail

Systematics Section/ASPT

Wight, Spencer Friend [1], Stange, Carolyn [2], Samis, Flora [3], Charboneau, Joseph [4], Levin, Jonathan [3], Olvera, Hilda Flores [5], Booth, Helga Ochoterena [5], Douglas, Norman [6], Moore, Michael [7].

Exploring gypsum endemism, amphitropicaldisjunction, and phylogeographic structure in Gaillardia (Asteraceae).

The genus Gaillardia is comprised of 21 species that are collectively distributed across North America and southern South America, with a center of diversity in southwestern North America. This genus also includes seven gypsum endemic taxa in the Chihuahuan Desert and one additional species that grows primarily on gypsum in Utah and Arizona. Previous work suggests that gypsum endemism evolved at least three times in the genus, although population and species sampling were incomplete in these studies. In an effort to confirm the number of origins of gypsum endemism in Gaillardia, and to begin to understand the phylogeography of these taxa and other broadly distributed species in the genus, we sequenced the plastid rpl32/trnL and ndhF/rpl32 spacer regions as well as the nuclear ITS region for multiple populations of all species but one (the rare G. tontalensis of Argentina) in the genus. Phylogenetic analyses of these data reveal some incongruence between plastid and ITS data, although relationships from the ITS tree are more congruent with morphology. The ITS tree confirms three evolutionary origins of gypsum endemism in the genus, including the existence of two gypsum endemic clades (one containing G. multiceps and G. turneri, and the other containing G. candelaria, G. henricksonii, and G. powellii). The ITS tree also suggests that allopatric speciation best explains the species diversity within these clades. The ITS tree also reveals significant phylogeographic structure within the widespread annual species G. pulchella, and supports the existence of an undescribed taxon in south Texas with close affinities to G. suavis. The ITS and plastid data indicate that the South American species G. megapotamica is most closely related to a clade of North American taxa that includes several gypsum endemic taxa.

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Phylogenetics and phylogeography of Chihuahuan Desert gypsum endemics

1 - Oberlin College, 1079 Pipestem Place, Rockville, MD, 20854, United States
2 - Oberlin College, Department of Biology, 119 Woodland St. , Oberlin, OH, 44074, USA
3 - Oberlin College, 119 Woodland St., Oberlin, OH, 44074, United States
4 - University of Wyoming, Department of Botany, 1000 E. University Ave., Laramie, WY, 82071, USA
5 - Instituto de Biologia, UNAM, Departamento de Botanica, Apartado Postal 70-233, Mexico, DF, C.P. 04510, Mexico
6 - Oberlin College, Biology, 119 Woodland St., Oberlin, OH, 44074, USA
7 - Oberlin College, 119 Woodland St., Science Center K111, Oberlin, OH, 44074, USA

Gypsum endemism
edaphic endemism
plastid sequences

Presentation Type: Oral Paper:Papers for Sections
Session: 35
Location: Versailles Ballroom/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 4:15 PM
Number: 35011
Abstract ID:642
Candidate for Awards:None

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