A research consortium led by scientists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) has found that social behavior and social status are reflected in the molecular level of gene activation, or epigenome, in both juvenile and adult spotted hyenas. The researchers analyzed non-invasively collected gut epithelium samples from both high-ranking and low-ranking female hyenas and discovered that rank differences were associated with epigenetic signatures of social inequality in several genome regions. These findings, published in Communications Biology, enhance understanding of epigenetic mechanisms in the interplay of social, environmental, and physiological factors in spotted hyenas.
In mammals, social behavior and status can significantly impact survival, reproductive performance, and overall health. Scientists from Leibniz-IZW found that social status influenced epigenetic patterns, specifically DNA methylation, in both young and adult female spotted hyenas. DNA from gut epithelium cells was analyzed from 18 adult females and 24 cubs with known social status in the Serengeti National Park. The researchers identified 149 genome regions where high-ranking and low-ranking individuals differed in DNA methylation, indicating epigenetic signatures of social inequalities in spotted hyenas.
The study revealed that these epigenetic signatures are stable across life stages and are linked to important physiological processes, such as energy conversion and immune response. Many differentially methylated regions were involved in regulating energy conversion, immune response, glutamate receptor signaling, and ion transportation. The differences in gene methylation patterns were particularly pronounced in genes involved in energy conversion, suggesting an adjustment by low-ranking adult females to the higher energetic costs of foraging trips. These findings provide insight into the connection between social factors and physiological processes in spotted hyenas.
The research benefitted from the expertise in epigenetics at Leibniz-IZW and data from the long-term Serengeti Hyena Project, which has been studying spotted hyenas since 1987. By studying individually known females with tracked social statuses, researchers were able to investigate the links between behavior, physiology, epigenetic modifications, and fitness in a wild population. Samples were collected non-invasively from fresh droppings, allowing for the enrichment of hyena DNA and improved sequencing data quality. The capture methylation method utilized enabled the analysis of DNA methylation patterns in a minimally invasive manner.
DNA methylation, a chemical modification of genetic material, plays a crucial role in determining gene activation or suppression within a cell. Spotted hyenas, known for their complex social structure, provide a model for studying social status-related differences in life history traits, physiological processes, and health. Social status in hyena clans is behaviorally inherited and stable across generations, with high-ranking females having priority access to resources and transmitting benefits to their offspring. The stable social structure and predictability of social status in hyenas is determined by family relationships and behavioral conventions passed down through generations.
