Predictors of variation in the secondary metabolites of Usnea strigosa
Jordan Cannon and Ayla Edmiston
WINNER OF THE JUDGE’S CHOICE AWARD
The basic chemical composition of common lichens is often well known because it is required for the successful identification of lichen taxa; however, spatial and temporal variation in the suite of secondary metabolites produced by lichens is not well understood. Using a common lichen, Usnea strigosa, we investigated chemical variation both temporally and at multiple spatial scales ranging from intra-individual variation to population-level variation throughout Upstate South Carolina. Lichens were collected from locations throughout the study area, and thin-layer chromatography was used to identify and compare the suites of potential secondary chemicals (PSCs) found in our samples. On the broadest spatial scale, we found substantial variation in PSCs both between and within populations throughout Upstate South Carolina. On a smaller spatial scale (within the city of Greenwood), we still detected variation both between and within sites. Within single sites, we were able to identify variation at the substrate level. However, we found virtually no detectable intra-individual variation in PSCs, and we failed to detect significant temporal variation in PSCs. These results suggest that there may be significant undescribed variation in the secondary chemistry of U. strigosa across many spatial scales. This contrasts with historical evidence that the chemistry of U. strigosa is simple, with a small number of known chemotypes found in predictable locations throughout its large geographic range.
Jordan Cannon graduated from Spring Hill High School in Chapin, SC and is a senior biology major with minors in chemistry and psychology. She interned with Greenwood Genetic Center during the summer of 2021 and is working toward becoming a genetic counselor.
Ayla Edmiston graduated from Airport High School in West Columbia, SC and is a senior biology major with minors in psychology and forensic science. Her achievements include receiving awards for presentations at the Association of Southeastern Biologists regional meeting and the South Carolina Upstate Research Symposium.