Estes, Dwayne , Small, Randall .
Molecular phylogenetic relationships,morphological evolution, and biogeography of Gratiola (Plantaginaceae) with new insights on the status of Fonkia , Sophronanthe ,and Tragiola.
Gratiola, the fourth largest genus of the predominantly Neotropical tribe Gratioleae, comprises 36 wetland-adapted species distributed throughout temperate, tropical-montane, and subtropical regions of the Americas, Eurasia, and Australasia. Little systematic work has been conducted on the genus and the last worldwide taxonomic treatment was prepared 163 years ago. During this time, one new section has been established, three monotypic genera have been segregated from Gratiola, several new species have been described, and several species remain undescribed. Given this, the genus is in need of detailed systematic work. In this study, a phylogenetic hypothesis is presented for Gratiola based on chloroplast DNA sequence data from the trnS-trnG intergenic spacer and trnG intron as well as the trnQ-rps16 intergenic spacer. All but two of the 36 species of Gratiola were sampled resulting in a robust phylogenetic assessment. The phylogeny was used to examine morphological evolution within the genus as well as historical biographical patterns. The results from the phylogenetic analyses indicate that Gratiola sensu lato consists of four major clades. Another finding was that sect. Sophronanthe is monophyletic, however, sect. Nibora and sect. Gratiola are not. Many of the species formerly recognized as part of sect. Nibora form their own strongly supported clade and should be placed in their own section. The results from the morphological analysis indicate that Gratiola s.l. is not supported by any morphological synapomorphies. Both Gratiola sensu stricto and Sophronanthe are each supported by morphological synapomorphies. Results from the biogeographical analysis indicate that Gratiola as well as the four major clades of the genus likely originated in North America. Finally, the monotypic genus Fonkia was found to be phylogenetically embedded within Gratiola supporting the recognition of this taxon as Gratiola uliginosa, and this study provides additional support for the recognition of Sophronanthe (including Tragiola) as a distinct genus.
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1 - Austin Peay State University, Department of Biology & Center of Excellence for Field Biology, P.O. Box 4718, Clarksville, TN, 37044, USA
2 - University of Tennessee, Department of Ecology and Evolutionary Biology, 442 Hesler Biology, Knoxville, Tennesee, 37996, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Rendezvous A/Snowbird Center
Date: Tuesday, July 28th, 2009
Time: 10:00 AM