Fig. 2
Comparison of gene duplicates over developmental stages and intestinal regions. a The distribution of expressional differences between of genes in each homologous gene family. Gene expression in transcripts per million (TPM) was compared between pairs of every gene homolog, by taking the ratio of the higher expressed gene (TPMDup1) over the lower expressed (TPMDup2). Expression ratios of gene pairs were calculated for each tissue and development stage. The density of expression ratios on a log2 scale is showed for Ss4R and non-Ss4R homolog gene pairs. A t-test between mean expression ratios of Ss4R and non-Ss4R showed a significant (p = 2.25 × 10− 7) difference. b Comparison of pcyt1 genes in TPM over developmental stages and intestinal regions. The gene expressions were compared over three developmental stages (0.16, 2.5 and 10 g) in stomach (SM), pyloric caeca (PC) and hindgut (HG) of salmon. Numbers after underline indicates Ss4R gene duplicates specific in salmonids