Silveira, Michael , Simpson, Michael .
Mesa mints and bearded ladies: phylogenetic systematics of Pogogyne (Lamiaceae).
Pogogyne (Lamiaceae) is a small genus of annual plants, occurring almost entirely in vernal pool habitats. Little has been known about the phylogenetic relationships of this complex. To assess this, DNA sequence data from the trnQ-rps16 chloroplast spacer and both ETS and ITS nuclear regions were obtained from all seven extant species and several putative outgroups. Both parsimony and Bayesian phylogeny reconstruction methods were used to infer relationships within the genus. Ancestral state reconstructions were performed for characters that have been used to separate groups within Pogogyne. This study indicates that subgenus Hedeomoides (consisting of P. floribunda, P.serpylloides, and P. zizyphoroides) is monophyletic and diagnosed by a reduction in stamen number from four to two and by a corolla included within the bracts and calyces. Subgenus Pogogyne (consisting of P. abramsii, P. clareana, P. douglasii, and P. nudiuscula) is paraphyletic, but with poor support. Only two species, P.clareana and P. nudiuscula, were shown to be definitively monophyletic. Several clades are correlated with biogeographic distribution. Pogogyne possesses a relatively long stem lineage, but the crown Pogogyne clade has short branches and is roughly estimated to have originated approximately 1-1.2 million years before present, corresponding with estimates of the age of vernal pool ecosystems. These results support the hypothesis that the members of Pogogyne underwent a rapid, adaptive radiation in response to specialization to a periodically inundated habitat.
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1 - PO Box 2211, Palm Desert, CA, 92261, USA
2 - San Diego State University, Department Of Biology, Department Of Biology, San Diego, CA, 92182, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Delaware C/Hyatt
Date: Wednesday, July 11th, 2012
Time: 10:30 AM