Epigenetic mechanisms modulate differences in <i>Drosophila</i> foraging behavior.

Abstract

Little is known about how genetic variation and epigenetic marks interact to shape differences in behavior. The <i>foraging</i> (<i>for</i>) gene regulates behavioral differences between the rover and sitter <i>Drosophila melanogaster</i> strains, but the molecular mechanisms through which it does so have remained elusive. We show that the epigenetic regulator <i>G9a</i> interacts with <i>for</i> to regulate strain-specific adult foraging behavior through allele-specific histone methylation of a <i>for</i> promoter (pr4). Rovers have higher pr4 H3K9me dimethylation, lower pr4 RNA expression, and higher foraging scores than sitters. The rover-sitter differences disappear in the presence of <i>G9a</i> null mutant alleles, showing that <i>G9a</i> is necessary for these differences. Furthermore, rover foraging scores can be phenocopied by transgenically reducing pr4 expression in sitters. This compelling evidence shows that genetic variation can interact with an epigenetic modifier to produce differences in gene expression, establishing a behavioral polymorphism in <i>Drosophila</i>.