A culturally transmitted foraging technique in Indo-Pacific bottlenose dolphins can be predicted by DNA-methylation levels

Cultural repertoires can influence access to resources and fitness across species, impacting individuals' environmental niches and social networks. Such behaviours may induce potentially reversible changes in gene expression via epigenetic mechanisms like DNA methylation, thus capturing cultural behaviour on a molecular level. Some Indo-Pacific bottlenose dolphin (Tursiops aduncus) in Shark Bay, Western Australia, use marine sponges as foraging tools and exhibit differences in diet, sociality and survival compared to dolphins that use the same habitat but lack the tool-using know-how ('non-spongers'). We investigated the relationship between this culturally transmitted behaviour and skin DNA methylation patterns at 29 812 cytosine-phosphate-guanine (CpG) sites of the HorvathMammalMethylChip40. Machine learning models, based on differences in DNA methylation at specific CpG sites, showed moderate ability to discriminate between spongers (n = 23) and non-spongers (n = 73; area under the curve = 0.68). Permutation tests indicated that our main machine learning model performed significantly better than random at differentiating spongers from non-spongers, suggesting that DNA methylation patterns contain information associated with sponging behaviour. Our study on the nexus between epigenetics and cultural evolution opens a promising avenue of research on the molecular underpinnings of cultural practises, important to the biology of humans and other animals. This article is part of the theme issue 'Ecological epigenetics at the intersection of behaviour and life history variation in non-model animals'.