Faculty Directory

The core of my research is trying to understand the evolution of sensory systems using the unique cyclopean auditory system of praying mantises as a model system and also extending the studies to other insects. The community of scientists who focus on this question is small, not because the questions are uninteresting - they deal with the evolution of nervous systems, after all - but in significant part, because the work demands studies that can take years to complete. The primary technique used for evolutionary studies is comparisons among large numbers of species from different lineages and from different locations around the world. Thus, our comparative work on tiger beetle behavior took >4 years and extensive travel across North America, South America, and India. Our current work on the phylogeny of the mantis ear has taken >15 years, travel to major museums in North America and Europe, and multiple collecting trips to all continents except Antarctica. The payoff, however, is worth this effort and leads to more global insights into sensory evolution. One of my most cited papers is a review article that draws together those ideas and proposes new ways of thinking about auditory evolution in insects. In parallel neurophysiological studies, we are analyzing the changes that take place within the central nervous system as a whole and in individual neurons. We integrate those studies with our third parallel research effort focusing on behavioral experiments that examine the ways the auditory system enhances the fitness of the animals. My lab is one of only 2-3 in the world that takes such a comprehensive, multi-level approach to the evolution of insect auditory systems. A major accomplishment of the last few years was completion of a long paper (Yager and Svenson, 2008). This papers has been cited as one of the very first models synthesizing anatomical, neurophysiological, behavioral and molecular data simultaneously to elucidate the evolution of a sensory system. My recently funded NSF grant continues the themes of the lab, but also takes us into the realm of evolutionary bioacoustics. I have suspected, based on research done by some undergrads in my lab, that even though mantises have only one ear, they may have as many as four eardrums. We continue a project of ultra-high resolution 3D CAT scans created using the synchrotron at Argonne National Lab to explore this possibility. So far, I have collected 4 terabytes of data that we are processing to create 3D graphic images of internal auditory system structure. I have expanded this project to include laser vibrometry measurements of tympana vibration which involved collaborative research at the University of Southern Denmark.

Background

After graduating from Wesleyan University in Connecticut, Dr. Yager went to the University of Michigan Medical School. There he learned for the first time about the intimate linkage between brain function and behavior. This realization, coupled with a low affinity for working with sick humans, led him away from medicine and into the Ph.D. program in Neurobiology and Behavior at Cornell University. The first portion of his doctoral studies (with Robert Capranica) focused on communication underwater using sounds by African clawed frogs (Xenopus). The project included nine months of nocturnal field research in western Kenya. The second portion (with Ronald Hoy) grew out of his discovery of hearing in praying mantises. After completing his doctorate, Dr. Yager stayed at Cornell to do postdoctoral research with Carl Hopkins. The project involved neural recording in the central nervous system of weakly electric fish. He has been on the faculty at the University of Maryland at College Park since 1990. Funded by NIH and NSF, Dr. Yager’s research continues to focus on the linkage between brain function and behavior using insect auditory systems as models.

• Evolution of sensory systems
• Auditory evolution in insects
• Synthesis of anatomical, neurophysiological, behavioral and molecular data simultaneously to elucidate the evolution of a sensory system
• Evolutionary bioacoustics