Used in conjunction, the rbcL+matK gene regions have yielded relatively high species discrimination at a relatively low cost in previous studies. Here, we examined the effectiveness of these barcodes to distinguish species in a complex prairie flora that includes a high proportion of polytypic genera. 475 samples representing 204 species from 108 genera in 31 families were collected from the Black Belt prairie region of Alabama and Mississippi. Following high-throughput sequencing at the Canadian Centre for DNA Barcoding, contiguous sequences were downloaded from BOLD Systems for all-to-all BLASTn analyses. Although sequencing success was relatively high for rbcL (91%) and matK (68.2%), complete coverage for both regions was marginal (62.9%). Species resolution was relatively low for rbcL (44.0%) and matK (43.1%) but increased for the combined barcode (51.0%). Monotypic genera were 2.8 times more likely to be successfully distinguished than polytypic taxa (mean species resolution was 88.9% for monotypic taxa and 35.7% for polytypic taxa). Furthermore, there was a significant, negative correlation between the number of species per genera and percent species resolution. The results suggest that for floras with a high number of closely related species, additional gene regions will be required to supplement the rbcL+matK barcode.
1 Dept of Biology, Columbus State University, Columbus, GA; 2 Dept of Biology, Columbus State University, Columbus, GA; 3 Dept of Biology, Columbus State University, Columbus, GA
148 • Peter W. Schafran1, W. Carl Taylor2, Rebecca D. Bray1, Jay F. Bolin3, Lytton J. Musselman1
Systematics of the Genus Isoetes (Isoetaceae, Lycophyta) in the Southeastern United States
Quillworts (Isoetes spp., Isoetaceae, Lycophyta) have been studied in the southeastern U.S. for nearly two centuries, yet their taxonomy and systematics are still poorly understood. Currently, twenty-five taxa are described in the region - twelve diploids, eight tetraploids, three hexaploids, one octoploid, and one decaploid. In addition to these there are three described hybrids, one diploid and two triploids. We have identified several undescribed diploids and tetraploids. Morphological characteristics are of limited taxonomic value, so specimens are often misidentified and taxa unnecessarily lumped or split. Molecular techniques have aided in unraveling this case of reticulate evolution, illuminating relationships between species and parentage scenarios of the numerous polyploids. Some allopolyploid species are polyphyletic with parentage varying by population. We expect to discover more with additional field work. We present a review of Isoetes in the Southeast based on current molecular, cytological and morphological evidence, focusing on the basic diploids, hybridization events, and the role of reticulate evolution in the group.
1 Dept of Biological Sciences, Old Dominion University, Norfolk, VA; 2 National Museum of Natural History, Smithsonian Institute, Washington, D.C.; 3 Dept of Biology, Catawba College, Salisbury, NC
149 • Brianna L. Taylor, Naomi Jackson, Benjamin J. Thornton
The Effects of Ascorbic Acid on Drosophila melanogaster Susceptibility to Permethrin and Suppression of Cytochrome P450 Activity
Permethrin, 3-Phenoxybenzyl (1RS)-cis,trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate, is a widely used pesticide in the United States as well as other countries around the world. Because of the pervasive use many non-target species are exposed resulting in challenges to individuals and possibly populations. An organism’s defense against toxins in general, including permethrin, is via detoxification by ubiquitous enzyme systems, such as cytochrome P450s. Their role in the detoxification process is to oxidize xenobiotics, thereby increasing solubility in water and promoting excretion (Zhu et al. 2008). A number of studies have shown that dietary vitamin supplementation can enhance detoxification (Brodfuehrer & Zannoni 1986; Zannoni et al. 1982). The current study tested the susceptibility of Drosophila melanogaster to permethrin subsequent to exposure to various concentrations of ascorbic acid. Percent survivorship was determined revealing a sex-dependent response. Ascorbic acid supplementation had no observable effect on female susceptibility to permethrin. Males exposed to 15% ascorbic acid exhibited a significant increase in survivorship compared to controls. Lang and Liu (2013) showed that elevated P450 gene expression enhanced resistance to Permethrin in Culex auinquefasciatus. In this investigation, males exposed to 15% and 20% ascorbic acid showed an unexpected significant decrease in cytochrome P450 enzyme activity compared to the control. Females showed a similar change in P450 activity in the 20% exposure only. These documented changes in P450 activity do not explain the observed increased resistance to Permethrin in male D. melanogaster.
Biology and Allied Health, Southern Adventist University, Collegedale, TN
