When inequality is more than “skin-deep”: Social status leaves traces in the epigenome of spotted hyenas in Tanzania
A research consortium led by scientists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) provide evidence that social behaviour and social status are reflected at the molecular level of gene activation (epigenome) in juvenile and adult free-ranging spotted hyenas. They analysed non-invasively collected gut epithelium samples from both high-ranking and low-ranking female hyenas and showed that rank differences were associated with epigenetic signatures of social inequality, i.e., the pattern of activation or switching off of genes that regulate important physiological processes such as energy conversion and immune response in several genome regions.
The results, published in the scientific journal “Communications Biology”, contribute to a better understanding of the role of epigenetic mechanisms in the interplay of social, environmental and physiological factors in the life of a highly social mammal.
In mammals, social behaviour and social status can substantially influence the survival, reproductive performance and health of individuals. However, it is not yet fully understood how the translation of social and environmental factors into the physiology of an organism is reflected in molecular processes. Now, scientists from the Leibniz-IZW Department of Evolutionary Genetics and the Serengeti Hyena Project at the Leibniz-IZW’s Department of Ecological Dynamics found that social status influenced epigenetic patterns, more specifically the methylation of DNA in both young and adult female spotted hyenas (Crocuta crocuta) which determines the activation of genes. They analysed DNA from gut epithelium cells from 18 adult female hyenas and 24 cubs with known social status from three clans in the Serengeti National Park, Tanzania. The scientists identified and validated 149 genome regions, where high-ranking and low-ranking individuals differed in the methylation of DNA (differentially methylated regions, DMRs). “We could, for the first time, provide evidence for epigenetic signatures of social inequalities in both young and adult spotted hyenas”, says Dr Alexandra Weyrich, head of the working group “Wildlife Epigenetics” in the Leibniz-IZW Department of Evolutionary Genetics and senior author of the paper.
The findings show that these epigenetic signatures are stable across life stages – and that they are linked to important physiological processes: Many of the identified DM
