Battle of the variants: Is space or time a better predictor of variation in lichen secondary chemistry?
Document Type
Event
Abstract
The basic chemical composition of common lichens is often well known because it is required for the successful identification of lichen taxa; however, the ecological roles of the secondary metabolites produced by lichens are just starting to be investigated. Previous studies have explored temporal variation in a single secondary chemical, but temporal variation in the entire suite of secondary metabolites produced by lichens has not been routinely explored. In this study, we examined temporal variation in all potential secondary chemicals of Usnea strigosa, a lichen common to our region. Between August and November, we collected 10 U. strigosa samples weekly for twelve weeks from downed limbs in a single population. To identify potential secondary compounds, we used thin-layer chromatography and ran the plates in solvent C (170 toluene: 30 acetic acid). Visualization of the plates was completed in daylight, UV light, and again after the addition of 10% sulfuric acid and 20 minutes of heat (110 C). We used ANOSIM to quantify changes in chemistry over time, which allowed us to detect differences between collection weeks. We then visualized our data using non-metric multidimensional scaling (NMDS). We found what initially appeared to be temporal differences in secondary chemistry (p = .001). However, upon inspection of our NMDS plots, we found that the four groups identified in our ordination did not only differ temporally but also spatially (at the level of substrate or microscale). After removing the weeks in which samples were collected from different substrates (trees), we analyzed the remaining data (approximately 8 weeks of samples). In the subsequent NMDS plot, the samples were all part of one well-supported group (p = .001) showing no obvious temporal variation in secondary chemistry. Upcoming research will include a description of substrate-level differences in chemistry and collection of additional lichen samples from the collection area that showed minimal temporal variation.
Battle of the variants: Is space or time a better predictor of variation in lichen secondary chemistry?
Breakout Session A: Ecological Sciences
CLC BallroomThe basic chemical composition of common lichens is often well known because it is required for the successful identification of lichen taxa; however, the ecological roles of the secondary metabolites produced by lichens are just starting to be investigated. Previous studies have explored temporal variation in a single secondary chemical, but temporal variation in the entire suite of secondary metabolites produced by lichens has not been routinely explored. In this study, we examined temporal variation in all potential secondary chemicals of Usnea strigosa, a lichen common to our region. Between August and November, we collected 10 U. strigosa samples weekly for twelve weeks from downed limbs in a single population. To identify potential secondary compounds, we used thin-layer chromatography and ran the plates in solvent C (170 toluene: 30 acetic acid). Visualization of the plates was completed in daylight, UV light, and again after the addition of 10% sulfuric acid and 20 minutes of heat (110 C). We used ANOSIM to quantify changes in chemistry over time, which allowed us to detect differences between collection weeks. We then visualized our data using non-metric multidimensional scaling (NMDS). We found what initially appeared to be temporal differences in secondary chemistry (p = .001). However, upon inspection of our NMDS plots, we found that the four groups identified in our ordination did not only differ temporally but also spatially (at the level of substrate or microscale). After removing the weeks in which samples were collected from different substrates (trees), we analyzed the remaining data (approximately 8 weeks of samples). In the subsequent NMDS plot, the samples were all part of one well-supported group (p = .001) showing no obvious temporal variation in secondary chemistry. Upcoming research will include a description of substrate-level differences in chemistry and collection of additional lichen samples from the collection area that showed minimal temporal variation.