Fig. 1.

Distinctive immunological and genome-wide gene expression signatures occurred at seasonal extremes. a Gene sets with significant summer (red) or winter (blue) expression bias as indicated by gene set enrichment analysis (GSEA). Ranked differential gene expression was compared, separately for the RHD and FRN sites, to global KEGG and REACTOME gene sets, and sets are shown where the combined FDR P value was significant (<0.05); gene set names are truncated but shown in full in Additional file 2: Table S2; stars indicate immunologically-relevant gene sets; the central dendrogram indicates the degree of overlap between gene sets. b Analyses of selected gene sets (Additional file 3: Table S3) representing immunological pathways and organismal signatures of stress, reproduction, growth and metabolism. Individual colour panels correspond, left to right, to the order of gene sets in Additional file 3: Table S3. These sets were considered by GSEA for RHD and FRN separately, and by gene overlap (hypergeometric distribution) for the overall summer and winter-biased gene sets (defined as those genes having significant expression differences, in the same direction, at both FRN and RHD)