Examining potential tradeoffs between chemical and physical defenses in goldenrod
Tall goldenrod plants (solidago altissima) typically grow as a single, erect stem. However, some genotypes of goldenrod exhibit a “candy-cane” phenotype, where the apical tip of the plant bends downward. Previous research from the Abrahamson lab at Bucknell University has found that the ducking-stem phenotype is an effective defense against insect herbivores, such as the Eurosta gall fly, that attack the apical tip of the plant. This is because the plants can effectively hide from the herbivores, while their more-apparent neighbors are damaged instead. Our research current research aims to investigate whether the ducking-stem plants are more susceptible to insect herbivores, compared to the erect-stem genotypes. We hypothesize that 1.) the ducking-stem plants will have reduced chemical defenses because of reduced selection pressure from herbivores or 2.) the ducking-stem plants will have reduced chemical defenses because of altered phytohormone concentrations possibly involved in maintaining this phenotype. My undergraduate and high-school students are actively researching these hypotheses and we hope to post some of the exciting results soon!