Living at high density and low genetic diversity are factors that increase an organism’s susceptibility to disease. Thus, community-living organisms, especially inbred ones, should be particularly vulnerable to infection and therefore have special strategies to cope with infection. Phenotypic plasticity underpinned by epigenetic changes may allow community-living organisms to rapidly respond to infection threats. To explore the potential role of epigenetic modifications in immune responses to community-living species with low genetic diversity, we compared genome-wide DNA methylation profiles of five colonies of the social spider (Stegodyphus dumicola) from their natural habitat in Namibia just before they died from infection to a time point at least 6 months earlier when they were presumably healthier. Genome-wide and chromosome-wide methylation levels were elevated in CpG, CHG, and CHH contexts, but genome-wide changes were not clearly different from zero. These changes were most pronounced in the CHG context, particularly in a narrow region of chromosome 13, suggesting that this DNA methylation context plays a previously unsuspected role in phenotypic plasticity. However, at the base level there were few clear differential methylation patterns, and the average methylation change in genes with known immune functions in spiders was close to zero. Our results suggest that although on a large genome scale DNA methylation can change with infection, this type of epigenetic change is not necessarily essential for immune responses in social spiders.
Fisher, D.N., Bechsgaard, J. & Bilde, T. Examining changes in DNA methylation profiles of social spiders in all cytosine contexts following infection. Genetics (2024). https://doi.org/10.1038/s41437-024-00724-y
