Stutzman, Julia (Bridgewater College). Mentor: Laura Galloway (University of Virginia). Life history trade-offs in Campanulastrum americanum.
Abstract: Life history traits are those traits associated with growth, maintenance, resource acquisition, and reproduction. Life history traits typically do not change in isolation of one another, and as a result, trade-offs, either genetically or physiologically induced, will occur. Changing of one aspect of life history results in correlated changes in other aspects of life history. To observe these trade-offs, I examined the woodland herb, Campanulastrum americanum . C. americanum individuals grow as annuals or biennials, and populations are found in both understory and light-gap environments. Three generations of selections for early and late flowering time have been performed under controlled conditions, and I observed early and late flowering individuals from this genetic stock in a natural setting to determine if there are trade-offs between flowering time and other functions, like growth and herbivory levels and defense. I predicted that late lines, having more time before flowering, would be able to devote more resources to growth and defense. I measured the growth patterns including: main stem height, number of basal stem, number of branches, leaf length and width. The herbivory measurements included: number of damaged leaves per plant, number of insect-caused puncture wounds per plant, and a leaf trichome count. All measurements were done in both sun and shade environments to determine if there is a trade-off as a result of resource limitation. Analysis of resulting data determined that there are genetic trade-offs between early and late flowering lines involving plant height, leaf width, amount of both stem and leaf damage, and trichome counts. The environment played a key roll in determining how much these trade-offs were expressed, showing a physiological factor involved in trade-offs in C. americanum .