Changes in gene methylation and expression accompany caste specialization and ageing in a social insect. Formica exsecta

RNA sequencing and DNA methylation were used to study changes in brain gene expression and methylation in the ant Formica exsecta during development (between old adult and emerging adult) and between the female castes (queen and worker). We used traditional approaches (tests of differential methylation) with a novel approach (analysis of co-expression and co-methylation networks) to show that much of the transcriptome and methylome are organized in sets of genes, with most of them associated with caste and/or life stage phenotypic differences.