Additional Funding Sources
This project was made possible by the NSF Idaho EPSCoR Program and by the National Science Foundation under Award No. OIA-1757324.
Abstract
Drought has been increasing in intensity and frequency alongside soaring temperatures in the western United States. Sagebrush is a keystone species in this region threatened by anthropogenic climate change. This project investigated the adaptive capacity of sagebrush populations to cope with climate change by focusing on studying water use efficiency by way of stomatal clustering. This study developed a new means of characterizing clusters with low resolution data. We hypothesized that there would be significant differences in the clustering characteristics of the sagebrush in each of the sample locations due to differences in the climates of the sample locations. Seedlings representing populations from Utah, Idaho, and Nevada were grown in a common garden. Leaf epidermis was removed and imaged with a microscope for analysis. An R script was developed to calculate probabilities of clustering events. Comparative statistics were performed on the outputs of this script as a means to compare clustering characteristics of sample populations. This script is one of the first tools developed to characterize clusters using low resolution data. We found that the sampled sagebrush displayed stomatal clustering and that the characteristics of the clustering did not significantly differ between the sample populations. However, this clustering was weak; the stomata were over-dispersed indicating that our sample populations were nearing peak water use efficiency in this regard. Future research should focus on other characteristics, such as stomatal size and density, to quantify water use efficiency as sagebrush show little capacity for adaptation in terms of stomatal clustering. Our developed tool can be utilized by other researchers also working on quantifying stomatal clustering to extend research further into other drought adapted plants.
When Math Meets Biology: Characterizing Stomatal Clusters
Drought has been increasing in intensity and frequency alongside soaring temperatures in the western United States. Sagebrush is a keystone species in this region threatened by anthropogenic climate change. This project investigated the adaptive capacity of sagebrush populations to cope with climate change by focusing on studying water use efficiency by way of stomatal clustering. This study developed a new means of characterizing clusters with low resolution data. We hypothesized that there would be significant differences in the clustering characteristics of the sagebrush in each of the sample locations due to differences in the climates of the sample locations. Seedlings representing populations from Utah, Idaho, and Nevada were grown in a common garden. Leaf epidermis was removed and imaged with a microscope for analysis. An R script was developed to calculate probabilities of clustering events. Comparative statistics were performed on the outputs of this script as a means to compare clustering characteristics of sample populations. This script is one of the first tools developed to characterize clusters using low resolution data. We found that the sampled sagebrush displayed stomatal clustering and that the characteristics of the clustering did not significantly differ between the sample populations. However, this clustering was weak; the stomata were over-dispersed indicating that our sample populations were nearing peak water use efficiency in this regard. Future research should focus on other characteristics, such as stomatal size and density, to quantify water use efficiency as sagebrush show little capacity for adaptation in terms of stomatal clustering. Our developed tool can be utilized by other researchers also working on quantifying stomatal clustering to extend research further into other drought adapted plants.