Fig. 6
Cluster and correlation analyses between gene expression and phenotypic traits. a Principal Component Analysis (PCA) based on 24 stress-related target genes and b 14 immune-related target genes. PCAs illustrate the differential gene expression profiles for salmon subjected to Control (CT: 12 °C, 100% air saturation), Warm & Normoxic (WN: 20 °C, 100% air sat.) or Warm & Hypoxic (WH: 20 °C, ~ 70% air sat.) conditions (n = 8 per treatment, N = 24 total). The ellipses denote the dispersion of variance with 95% confidence intervals around the center of the distribution for each treatment group. The variances explained by the Principal Components (PC-1 and PC-2) are indicated in percentage values (%). c Component maps for the Warm & Normoxic and d Warm & Hypoxic treatments based on 41 target genes and seven phenotypic traits [fork length (length), body mass (weight), condition factor (CF), specific growth rate (SGR), hepato-somatic index (HSI), spleen-somatic index (SSI) and relative ventricular mass (RVM)]. The diameter of the dots and label size reflect the contribution of the response variables (i.e., larger circles and labels indicate a greater contribution). Variables coloured in grey do not contribute significantly to either visualized component. Variables coloured in purple significantly contribute to the first component (CP-1) and variables in green significantly contribute to the second component (CP-2). Variables coloured in red significantly contribute to both CP-1 and CP-2. The variance explained by CP-1 and CP-2 are indicated in percentage values (%). e Ordered Pearson correlation matrix for Warm & Normoxic and f Warm & Hypoxic exposed fish between the gene expression (RQ) of 41 target genes and seven phenotypic traits. Positive correlations are in red (+ 1) and negative correlations are in blue (− 1), while the intensity of the colour and the size of the dots are proportional to the correlation coefficient. Non-significant correlations (p > 0.05) are not shown. The arrows proceeding a gene name indicate whether the gene was up-regulated (
) or down-regulated (
) based on the qPCR analysis