Genetic Basis for Aggression in the Fruit Fly
August 7, 2006
Contact:
Dr. Ralph J. Greenspan
ph: 858-626-2000
email: greenspan@nsi.edu

Genetic Basis for Aggression in the Fruit Fly

Scheduled for publication in Nature Genetics on August 13 online. Embargoed until 1 pm, August 13. Herman A. Dierick and Ralph J. Greenspan “Molecular analysis of flies selected for aggressive behavior.” Manuscript tracking number NG-A18334R1

When we think of aggression in the animal kingdom, fruit flies are not the first example to leap to mind. A new study, however, shows that non-fighting fruit flies can be made more aggressive by selective breeding, and that a gene likely to be involved in how flies perceive one another forms part of the genetic basis for the difference in fighting behavior.

One reason we think of fruit flies as placid is our exposure to laboratory strains of them in high school science class. Fruit flies obtained from the wild are much more aggressive, but they gradually lose it over several generations in the laboratory where it presumably is no longer being selected. By performing selective breeding of flies from a laboratory strain of Drosophila melanogaster and taking only the most combative ones, Drs. Herman Dierick and Ralph Greenspan of The Neurosciences Institute in San Diego derived strains of super fighters. Not only do they come to blows on any pretext, but they also escalate to the level of Hulk Hogan, tossing each other around the ring (see accompanying video). Dierick and Greenspan then analyzed the genetic differences between the super fighters and their unselected relatives and determined that one of the genes that enhances fighting behavior (cytochrome P450 6a20) is a member of a class of genes known to be involved in recognizing odors. (Odor is principally how fruit flies distinguish each other.) This result suggests that a key trigger of aggression depends on whether one fly perceives the other as an enemy.

Natural variations in behavior are seen in all species, but the genetic contributions to such variations have been notoriously difficult to track down. The fruit fly Drosophila, which has provided insight into the role of genes in a variety of behaviors, many of which have had important implications for humans, is one of the few animals in which such studies can be carried out. This is due to the surprising degree of genetic similarity, and also to the ease of experimental manipulation of their genes. In this new study, the range of fruit fly contributions to our understanding of the interplay of genes and behavior has now been expanded to encompass aggression.

Dr's. Dierick and Greenspan are fellows at The Neurosciences Institute, an independent, non-profit, privately supported, scientific research organization dedicated to studying the workings of the brain at the most fundamental level. Under the leadership of nobel laureate, Gerald M. Edelman, M.D., Ph.D., the Institute is dedicated to a research environment that encourages creativity and innovation in a collaborative atmosphere with true freedom of scientific inquiry, in the expectation that such an environment provides the best chance for making vital advances for the benefit of mankind.

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