Fig. 4: Associations of CpG sites with chronological age and seasons (day of the year) in blood of yellow-bellied marmots.

a, The y axis reports log transformed P values for the EWAS of chronological age. b,c, The y axis reports log transformed P values for two fixed effects of the GAMs of individual cytosines (dependent variable) for chronological age (b; cubic spline function; age GAM) and day of year (c; cyclic cubic spline function; season GAM). The CpG sites’ coordinates were estimated based on the alignment of mammalian array probes to yellow-bellied marmot genome assembly. For some of the most significant CpGs, the symbols of proximal genes are provided. The direction of associations with chronological age is highlighted for the significant sites, with orange for hypermethylated and blue for hypomethylated sites; the red dashed lines represent the significance threshold (P < 10⁻⁵). Note that the season effect is cyclical, and we show the direction of association with chronological age for the active season. d, Venn diagram showing the overlap of significant (P < 10⁻⁵) CpG sites between EWAS and the GAMs. The effects of age and season in the GAMs are represented separately.