Jeff Ahern

I am interested in the evolutionary ecology of plant-insect interactions. Specifically speaking, I am interested in the antagonistic interactions (i.e. herbivory) that drive microevolutionary changes in plant traits like chemical defense.

I am also interested in mechanisms that promote rapid evolutionary change. Evolutionary change is the result of the interactions between natural selection and genetic diversity in a population. It is often difficult to observe contemporary evolutionary change because natural selection reduces genetic diversity in a population to facilitate evolutionary change. Without genetic diversity encoding for a trait of interest, there cannot be evolutionary change.

Hybridization is a process that immediately increases the genetic diversity is a population of individuals. By increasing the genetic diversity in a population, hybridization is believed to be able to facilitate rapid evolutionary change.

My current project focuses on rapid chemical microevolution facilitated by hybridization between varieties of Common Cocklebur (Xanthium strumarium). Hybridization between subspecies and varieties of this species is reported to be common when they grow sympatrically. However, plants often self-pollinate, leading to differentiation between populations. Herbivore resistance is proposed to be chemically mediated in this species, and different varieties express different chemical phenotypes.

I plan to create synthetic hybrid lines formed by breeding chemically differentiated varieties of Xanthium strumarium. Following this I will establish replicate populations in the field and greenhouse, expose populations to novel herbivore pressures, and monitor changes in the chemical phenotypes of each population over subsequent generations.