Abstract Detail

Systematics Section/ASPT

Leatherman, Lila [1], Sanders, Jeffrey [2], Goldman, Madison [2], Douglas, Norman [1], Moore, Michael [1].

Phylogenetics and biogeography of Oenothera sect. Calylophus.

The Chihuahuan Desert of the southwestern United States and north central Mexico contains many scattered, island-like gypsum (CaSO4-2H2O) exposures. Although gypsum is inhospitable to most plants, forming a crust when dry, eroding when wet, and possessing few nutrients, more than 200 plant species are endemic to gypsum in the Chihuahuan Desert. Several genera within the Chihuahuan Desert contain multiple gypsum endemic taxa, and in many cases gypsum endemic species or clades are geographically widespread despite the isolation of individual deposits. Oenothera sect. Calylophus (Onagraceae) is comprised of six species and nine subspecies that are native to arid, semi-arid, and grassland regions in Chihuahuan Desert and the Great Plains. Section Calylophus contains two subsections, Calylophus and Salpingia, that differ in a number of floral and leaf characters. However, taxa within each subsection are sometimes difficult to distinguish morphologically. Though several species of sect. Calylophus have been collected on gypsum soils, the New Mexico and Texas taxon Oenothera hartwegii ssp. filifolia is largely restricted to gypsum soils (Towner 1977) and shares a geographic distribution highly similar to a number of other northern Chihuahuan Desert gypsum endemics, including Tiquilia hispidissima, Sartwellia flaveriae, Nama carnosum, and Nerisyrenia turneri. In northern New Mexico, populations of O. hartwegii growing on gypsum have been referred to ssp. fendleri, largely on the basis of wider leaves. The goals of this project are to produce a robust phylogenetic estimate for sect. Calylophus and to determine whether populations of O. hartwegii on gypsum are phylogenetically distinct from other taxa and populations within sect. Calylophus. To do this, ITS and several chloroplast spacer regions were sequenced for over 100 populations, including all taxa in sect. Calylophus. Phylogenetic analyses recovered three well-supported clades in section Calylophus. Subsection Calylophus comprised one clade, but subsect. Salpingia was not monophyletic. Instead, the southwestern Sky Islands species Oenothera toumeyi formed its own clade exclusive of the remaining members of subsect. Salpingia, which formed the third major clade. A confusing pattern of population-level diversity is evident within the first and last abovementioned clades.

Broader Impacts:

Related Links:
Phylogenetics and phylogeography of Chihuahuan Desert gypsum endemics

1 - Oberlin College, Department of Biology, 119 Woodland St., Oberlin, OH, 44074, USA
2 - Oberlin College, Department of Biology, 119 Woodland St., Oberlin, OH, 44074, United States

Keywords:
gypsum endemism
Calylophus
Oenothera
Chihuahuan Desert
Phylogenetics
Sky Islands
biogeography.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM
Number: PSY010
Abstract ID:588