Epigenetic signatures of social status in spotted hyena (Crocuta crocuta)

In mammalian societies, dominance hierarchies translate into inequalities in health, reproductive performance and survival. DNA methylation has been suggested to mediate the effects of social status into gene expression and phenotypic outcomes. Yet, a study of social status-specific DNA methylation profiles across age classes in a wild population is missing, as is the use of non-invasive sample materials that minimise the anthropogenic effects. We tested whether social status is reflected by specific DNA methylation profiles across age classes in free-ranging spotted hyenas (Crocuta crocuta). This social carnivore is living in groups structured by a linear dominance hierarchy, in which female social status influences access to resources, health, reproductive performance and survival, and movement patterns. Using non-invasively collected faecal gut epithelium cells from 42 female spotted hyenas (cubs and adults) with known social status in the Serengeti National Park, Tanzania, we combined a genome-wide DNA methylation analysis with inferential and predictive statistical approaches. We identified 149 robust differentially methylated regions between high-ranking and low-ranking females (rankDMRs). RankDMRs were overlapping genes associated with immune function, glutamate receptor signalling and energy conversion. Our results indicate that socio-environmental inequalities are reflected at the molecular level across age classes in a free-ranging wild population.