Majure, Lucas C. , Hodgson, Wendy , Judd, Walter , Williams, Norris , Neubig, Kurt Maximillian .
Out of the canyon: phylogenetic evidence for the biogeographic history of the iconic beavertail cactus and relatives.
The iconic beavertail cactus, Opuntia basilaris, is one of the most widespread species of Opuntia in the desert southwest; it is found widely in the Sonoran and Mojave deserts, as well as the southern portion of the Navajoan Desert, and is sister to the Polyacantha clade, a group of species known for its widespread taxa (e.g., O. fragilis), occurring from southern Texas and northern Mexico to Alberta and Ontario, Canada. However, the biogeographic history, and thus origin, of this unique group of species, known collectively as the Xerocarpa clade, has been little studied. We sampled all members of this clade, focusing on the O. basilaris species complex. We reconstructed the phylogeny of the diploids of the clade using nearly whole plastome data from genome skimming, and supplemented these data with Sanger sequencing of both diploids and their polyploid derivatives. Our phylogenetic topologies indicate that both the Polyacantha and the Basilaris clades evolved in or near the Grand Canyon region from where they subsequently spread broadly into the Mojave, Sonoran and Chihuahuan deserts, as well as into the Great Plains and other areas in the case of the Polyacantha clade. Numerous polyploid taxa, mostly putative allopolyploids, have formed from within and between those two clades, as well as among distantly related clades of Opuntia. In the case of the Polyacantha clade, polyploids tend to occupy the broadest ranges. The Grand Canyon region may have served as a refugium for the Xerocarpa clade, as well as a staging ground for further speciation at the polyploid level. However, polyploid derivatives of this group also have originated numerous times outside of the Grand Canyon Region. This work demonstrates a surprising biogeographic pattern with regards to diploids, spreading from north to south, contrary to several other groups of North American Opuntia that show the opposite pattern, from south to north.
1 - Desert Botanical Garden, Research, Conservation, and Collections, 1201 N. Galvin Parkway, Phoenix, AZ, 85008, USA
2 - University Of Florida, Department Of Biology, 220 Bartram Hall, PO Box 118525, Gainesville, FL, 32611-8525, USA
3 - University Of Florida, Florida Museum Of Natural History, PO BOX 117800, Gainesville, FL, 32611-7800, USA, 352/273-1964
4 - Southern Illinois University Carbondale, Plant Biology, Carbondale, IL, 62901, USA
Presentation Type: Oral Paper
Candidate for Awards:None