Fig. 2

Principal component analysis of differentially expressed genes (DEGs). Clustered groups of points contain similar gene expression. Density ellipses cover 95% of plots for each group. Queens were classified as'young'or'old'based on carbonyl levels in fat body tissue, with a threshold of 15.0 nmol/mg protein separating the groups. A 680 DEGs associated with queen age (young vs old) of 39 queens. B 24 queens sub-selected for youngest versus oldest queens represent 719 DEGs using Ward’s clustering method. Open circle indicates an outlier queen who was biologically old, but showed gene expression patterns like young queens. C 24 queens sub-selected for low (< 30% relative abundance) and high (> 60% relative abundance) of gut symbiont Commensalibacter melissae represent 1451 DEGs using Ward’s clustering method. Open circles indicate queens whose expression patterns did not align with expectations: biologically young queens with low C. melissae had gene expression patterns like old queens; two old queens had low C. melissae, but gene expression like young queens; and one biologically old queen had high C. melissae, and gene expression like young queens. D Venn diagram showing the relationship between differentially expressed genes (DEGs) identified in our two main comparisons. The left circle represents the 719 DEGs found when comparing young versus old queens based on biological age (carbonyl levels). The right circle represents the 1451 DEGs found when comparing queens with high versus low C. melissae abundance. The overlap (252 shared DEGs) indicates genes affected by both age and C. melissae abundance, while the non-overlapping portions represent genes uniquely associated with either age (467 DEGs) or C. melissae abundance (984 DEGs)