Richard Karban

I received my PhD from the University of Pennsylvania and then got a faculty job at the University of California, Davis where I have been ever since. I have been working on plant communication for 30 years. I am the author of two books on this subject – Induced Responses to Herbivory (1997) with Ian Baldwin and Plant Sensing and Communication (2015).

Plant communication: Diversity of “alarm calls” and their effectiveness
Damaged leaves of sagebrush emit volatiles that neighbors perceive and cause neighbors to increase levels of resistance. These induced responses increase survival of seedlings and production of new branches and inflorescences for mature plants. The volatile profiles (chemotypes) emitted vary among individuals within a population and among populations across the landscape. Individual plants respond most effectively to the volatiles of the same chemotype as themselves. Some populations contain many diverse chemotypes, others only one or two. Populations that experience high levels of herbivory have fewer chemotypes. This may be caused by two mechanisms. When risk of herbivory is high, selection may favor convergence of chemotypes since all individuals can recognize and respond to the cues of all neighbors. Alternatively, herbivory may be high because chemical diversity in the plant population is low. We evaluated these two alternative hypotheses by examining the fates of individuals with chemotypes that were rare relative to their neighbors. When overall levels of herbivory were high, individuals of rare chemotypes were particularly hard hit. This suggests that alarm calls (chemotypes) have converged when risk is high. This trend is similar to observations for bird alarm calls and chemotypes of goldenrod.