- Author: Kathy Keatley Garvey
DAVIS--Evolutionary-ecologist Nancy Moran of Yale University will present a "Major issues in Modern Biology" seminar, sponsored by the Storer Endowment in Life Sciences, on Wednesday afternoon, June 5 in the Genome Center Lecture Hall.
Her seminar, titled “Two Sides of Symbiosis in the Ecology and Evolution of Insect Hosts” is at 4:10 and will be followed by a reception in the executive meeting room of the Hyatt Hotel.
Graduate student Leslie Saul-Gershenz of the Neal Williams lab, UC Davis Department of Entomology, will host and introduce her.
Moran’s research involves the evolution of bacterial genomes and of symbiotic associations. She has shown that intimate symbiotic associations date to the origins of major groups of organisms, and she has used genomic and experimental work to show that these associations provide hosts with essential molecules and defenses. She also works on general principles involving the evolution of genomes in bacteria.
“The central role of microbial partners in animal ecology and evolution is more and more evident, but the consequences of associating with beneficial microbes can be mixed,” Moran says in her abstract. “Some of the best examples of how symbiosis affects host evolution and diversification are in insects. Members of this immense, diverse group use a great variety of ecological niches, and encounter many challenges, including nutritional limitations, threats from pathogens and predators, and thermal stress. Bacteria possess genes and pathways that can help insects to overcome these challenges, so it's not surprising that mutualistic associations between insects and bacteria are ubiquitous.
“Symbiont acquisition underlies the success and diversification of some major insect groups. Genomic approaches have elucidated details of these associations in sap-feeding insects such as aphids, revealing mechanisms by which bacterial symbionts assist with host nutrition or with defense against natural enemies. Some insects, such as cicadas and sharpshooters, depend on a small consortium of unrelated bacterial symbionts, and this dependence requires elaborate mechanisms for transferring and packaging the symbionts within the host body.
“But symbiosis has another side, as long-term dependence on symbionts can limit host tolerances, due to degenerative evolution of domesticated symbiotic partners. Obligate symbionts often exhibit signs of genomic degradation and reduction; indeed, the tiniest known bacterial genomes are those of insect symbionts. Insect hosts often are dependent on partners that are increasingly incapable of performing. One evolutionary solution is replacement of ancient symbionts with newly acquired ones, as seen in grain weevils and spittlebugs. Whether symbionts undergo this degenerative evolution depends on whether mechanisms for inter-host transmission impose strict clonality in symbiont populations. “
Moran joined the Yale faculty in 2010 as the William H. Fleming Professor in Ecology and Evolutionary Biology. She obtained her bachelor of arts degree from the University of Texas in 1976 and a Ph.D. in zoology from the University of Michigan in 1982.
From 1986 to 2010, Moran served on the faculty of the University of Arizona, where she was a Regents’ professor. She was awarded a MacArthur Fellowship in 1997, and was elected to membership in the National Academy of Sciences in 2004, the American Academy of Arts and Sciences in 2004, the American Academy of Microbiology in 2004, and the American Association for the Advancement of Science in 2007. In 2010, she was awarded the International Prize for Biology by the Japan Society for the Promotion of Science. She has published more than 190 scientific papers.
The Tracy and Ruth Storer Endowment in the Life Sciences funds the major issues in the Modern Biology Lecture series. This lecture series is designed to bring to Davis eminent biologists whose current work represents the cutting edge of their fields of inquiry. The lectures are open to the entire campus and other interested persons.