Presented By: Ecology and Evolutionary Biology
EEB Student Dissertation Defense - Standing armies and crystal swords: Defense evolution across wild grape
Carolyn Graham, PhD Student
Carolyn Graham, EEB PhD student, presents their dissertation defense.
Summary: The diversity of adaptations that plants demonstrate to defend themselves from herbivory has fascinated biologists for decades. To explain this wealth of defense traits, researchers have developed a body of theory that uses patterns of ecological pressures in the environment to predict investment in defense, but the importance of biological and geographic scale in determining which selective pressures dominate is only beginning to be tested. In this dissertation, I explore the patterns and processes of defense trait evolution in plants, examining whether defense investment across scales matches up with plant defense theory. Using the wild grape genus Vitis as my primary study system, I synthesize comparative trait and occurrence data with mechanistic investigations of the processes that shape trait investment. In my first two chapters, I use a phylogenetic framework to compare and contrast how patterns of trait evolution match up to plant defense theory depending on whether they are evaluated at the intraspecific or interspecific scale, while considering a large body of traits associated with defense. I found that trait-trait correlations are rare across Vitis species compared to trait-environment correlations, but that both types of interactions are scale-dependent. These results suggest that defenses in grape largely evolve independent of each other, but that features of the environment thought to correlate with herbivory pressure are relatively better predictors of defense trait evolution. My third and fourth chapters center on calcium oxalate crystals in plant leaves, an understudied trait that I use as a model to understand the mechanisms of plant defense evolution. As long as we have known about calcium oxalate crystal presence in plants, researchers have believed that these structures are defensive against herbivory, but recent literature has challenged that assumption. Through a systematic literature survey, I find that crystal morphologies correlate differentially with geographic parameters, suggesting that this morphological variation evolved in response to different ecological pressures. Additionally, through experimental diet manipulations using a generalist herbivore, I find that Vitis riparia-derived crystals do not operate as a defense against chewing arthropods, but do seem to serve as a dynamic storage system for calcium in grape. By linking phylogenetic comparative and experimental approaches in tests of theory, my dissertation provides us with a broader understanding of plant defense evolution in wild grape and beyond.
This is a hybrid event.
Join remotely: Join Remotely: https://umich.zoom.us/j/94285293918
Meeting ID: 942 8529 3918
Passcode: tuesem
Summary: The diversity of adaptations that plants demonstrate to defend themselves from herbivory has fascinated biologists for decades. To explain this wealth of defense traits, researchers have developed a body of theory that uses patterns of ecological pressures in the environment to predict investment in defense, but the importance of biological and geographic scale in determining which selective pressures dominate is only beginning to be tested. In this dissertation, I explore the patterns and processes of defense trait evolution in plants, examining whether defense investment across scales matches up with plant defense theory. Using the wild grape genus Vitis as my primary study system, I synthesize comparative trait and occurrence data with mechanistic investigations of the processes that shape trait investment. In my first two chapters, I use a phylogenetic framework to compare and contrast how patterns of trait evolution match up to plant defense theory depending on whether they are evaluated at the intraspecific or interspecific scale, while considering a large body of traits associated with defense. I found that trait-trait correlations are rare across Vitis species compared to trait-environment correlations, but that both types of interactions are scale-dependent. These results suggest that defenses in grape largely evolve independent of each other, but that features of the environment thought to correlate with herbivory pressure are relatively better predictors of defense trait evolution. My third and fourth chapters center on calcium oxalate crystals in plant leaves, an understudied trait that I use as a model to understand the mechanisms of plant defense evolution. As long as we have known about calcium oxalate crystal presence in plants, researchers have believed that these structures are defensive against herbivory, but recent literature has challenged that assumption. Through a systematic literature survey, I find that crystal morphologies correlate differentially with geographic parameters, suggesting that this morphological variation evolved in response to different ecological pressures. Additionally, through experimental diet manipulations using a generalist herbivore, I find that Vitis riparia-derived crystals do not operate as a defense against chewing arthropods, but do seem to serve as a dynamic storage system for calcium in grape. By linking phylogenetic comparative and experimental approaches in tests of theory, my dissertation provides us with a broader understanding of plant defense evolution in wild grape and beyond.
This is a hybrid event.
Join remotely: Join Remotely: https://umich.zoom.us/j/94285293918
Meeting ID: 942 8529 3918
Passcode: tuesem
