Jeff Ahern

I am interested in the evolutionary ecology of plant-insect interactions. Of these interactions, herbivory (the consumption of plant tissues) is probably the most ubiquitous. Since herbivores have the potential to reduce plant fitness, plants possessing traits that reduce the impact of herbivory (such as noxious chemicals) will be selected for in populations, leading to evolutionary change.

My dissertation research focuses of the evolutionary ecology of chemical variation in the Common Cocklebur (Xanthium strumarium). Specifically, I am investigating the implications of a chemical polymorphism in this species, concerning the stereochemistry of the lactone ring junction in sesquiterpene lactones. The lactones can be either cis- of trans-fused to the main sesquiterpene skeleton. My experiments have found that this chemical marker is correlated with chewing insect resistance; plants producing trans-fused lactones are more resistant to insect herbivory than plants producing cis-fused lactones.  Further research has investigated the effect of leaf damage on plant fitness (and thus, selection) and factors associated with the maintenance of this chemical polymorphism in Xanthium strumarium.