Meeting Abstract
Understanding the genetic mechanisms behind aggressive behaviors can yield insight into the formation of dominance hierarchies, and thus social systems in general. Studies in a range of taxa and levels of social complexity have identified numerous candidate genes for aggression. At the center of these studies is research into the effects of social experience and agonistic contest outcomes. Data has shown significant changes in brain gene expression resulting from repeated winning and losing, as well as changing dominance rank, primarily in obligately social species. However, our knowledge of the genetic underpinnings of behavior in subsocial organisms is relatively poor. Because subsociality represents the simplest form of social living, understanding the behavioral genetics of this level of sociality provides the basis for understanding all other forms of social living. Here we measured the effects of aggression and social experience on gene expression in the brain of a subsocial bee, Ceratina calcarata. We compared expression profiles of individuals that had experienced repeated winning, repeated losing, or a change in rank during repeated encounters. We found that consistent winning accounted for the majority of variation in brain gene expression, followed by changing rank over maintaining rank. Comparing the resulting differentially expressed genes and corresponding gene ontologies to those of a diversity of invertebrate and vertebrate taxa, we find similarly upregulated and enriched terms for memory/learning, axonogenesis, and transcription regulation. Significantly over-represented cis-regulatory elements potentially responsible for differential regulation of genes related to aggressive/dominant behavior are identified. We present evidence for both genetic and cis-regulatory mechanisms for aggression of broad interest to the study of social evolution.
