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School of Natural Sciences Seminar

July 31, 2017 - 6:00pm

School of Natural Sciences Seminar

Down the rabbit-hole: co evolution of obligate bacterial symbiosis in sap-feeding insects

Gordon M. Bennett, Ph.D.
Department of Plant and Environmental Protection Sciences
University of Hawaii, Manoa

Monday, July 31, 2017
Science and Engineering 1 Building, Room 270K


Plant sap-feeding insects (Hemiptera: Auchenorrhyncha) specialize on diets depauperate in essential nutrients. To solve this problem, species have allied with bacterial symbionts for over 300 million years. However, symbionts lose ~90% of their genes due to their permanent intracellular relationships with their insect hosts. My lab investigates the origins and co-evolution insect-bacterial symbioses on a genomic level. Our work has shown that insects rely on more than one bacterial symbiont that complement each other to synthesize all essential nutrients. However, bacterial nutritional responsibilities can vary between major host lineages. Aside from nutrition, symbionts have the smallest known bacterial genomes. Due to genetic drift and stochastic gene losses, bacterial genomic and cellular capabilities vary dramatically between different species and lineages. Such strict co-evolutionary mutualisms with decaying partners require hosts to continually adapt to support the essential, but incomplete capabilities of their symbiotic partners. Our current work shows that hosts have evolved to use distinct genetic mechanisms to support bacterial symbionts that have different origins and capabilities. Remarkably, some of these genetic mechanisms were horizontally transferred into the host genome from other bacteria.


Gordon is an Assistant Professor in the Department of Plant and Environmental Protection Sciences at the University of Hawaii, Manoa. His work seeks to understand how insects and microbial symbioses co-evolve and interact to shape biological diversity. The questions his lab currently focuses on are (a) how insect-microbial interactions influence insect ecology and diversity; (b) the origins and patterns of genomic co-evolution in ancient bacterial-insect nutritional symbioses; and, (c) how host-symbiont functions and metabolisms are integrated on a cellular level. He also works on several projects identifying insect vectors of microbial plant pathogens in Hawaii. Gordon is a trained entomologist and is an expert in leafhopper (Cicadellidae) systems. His current projects use leafhopper species from Hawaii and California as novel model systems to address research aims. Prior to joining UH Manoa, Dr. Bennett was a USDA NIFA Postdoctoral Fellow at the University of Texas, Austin. He also completed a one-year postdoc appointment at Yale University. He earned his Ph.D. in Environmental Science, Policy, and Management at the University of California, Berkeley. He obtained his Bachelor’s degree in Secondary Education and Biological Sciences at the University of Vermont.