Fig. 4: Grassland-specific transcriptional responses to warming.

Warming-induced differential transcription levels, in transcripts per million (TPM), of genes and enzyme families involved in the degradation of chitin (A, E), nucleic acids (B, F), cell walls (C, G) and proteins (D, H) in the MTW and LTW grasslands. The boxplots depict an aggregated sum of transcripts mapped to genes assigned to the degradation of a particular substrate relative to all transcripts, according to ambient or warmed (+6 °C) conditions. Significant differences between ambient and warmed conditions for each substrate were assessed by parametric or nonparametric t-tests, depending on whether or not the variable met the assumptions (Table S7). All p values were adjusted for the false-discovery rate (Benjamin–Hochberg correction). Heatmaps were built using TPM normalized count matrices for each substrate and depict the different functional domains (Pfams) assigned to a substrate. The data were normalized by row (z score) and clustered using complete linkage, according to similar abundance patterns. The superscripted numbers indicate the number of Pfams aggregated in each category. The percentage of variation explained by temperature is shown on top of the heatmaps (PERMANOVA analysis).