Phenotypic plasticity, the ability of an organism to alter its phenotype in 
response to an environmental cue, facilitates rapid adaptation to changing 
environments. Plastic changes in morphology and behavior are underpinned by 
widespread gene expression changes. However, it is unknown if, or how, genomes 
are structured to ensure these robust responses. Here, we use repression of 
honeybee worker ovaries as a model of plasticity. We show that the honeybee 
genome is structured with respect to plasticity; genes that respond to an 
environmental trigger are colocated in the honeybee genome in a series of gene 
clusters, many of which have been assembled in the last 80 My during the 
evolution of the Apidae. These clusters are marked by histone modifications that 
prefigure the gene expression changes that occur as the ovary activates, 
suggesting that these genomic regions are poised to respond plastically. That 
the linear sequence of the honeybee genome is organized to coordinate widespread 
gene expression changes in response to environmental influences and that the 
chromatin organization in these regions is prefigured to respond to these 
influences is perhaps unexpected and has implications for other examples of 
plasticity in physiology, evolution, and human disease.