Fast transcriptional responses to domestication in the brook charr Salvelinus fontinalis

Domestication has been practiced for centuries yet directed toward relatively few terrestrial crops and animals. While phenotypic and quantitative genetic changes associated with domestication have been amply documented, little is known about the molecular changes underlying the phenotypic evolution during the process. Here, we have investigated the brook charr (Salvelinus fontinalis) responses to artificial selection by means of transcriptional analysis of approximately 32,000 cDNA features performed in both selected and control populations reared under identical environmental conditions during four generations. Our results indicate that selective breeding led to significant changes in the transcription of genes at the juvenile stage, where we observed 4.16% (156/3750) of differentially expressed genes between the two lines. No significant genes were revealed at the earlier life stage. Moreover, when comparing our results to those of previous studies on Atlantic salmon that compared lines that were selected for five to seven generations for similar traits (e.g., growth), genes with similar biological functions were found to be under selection in both studies. These observations indicate that (1) four generations of selection caused substantial changes in regulation of gene transcription between selected and control populations and (2) selective breeding for improving the same phenotypic traits (e.g., rapid growth) in brook charr and Atlantic salmon tended to select for the same changes in transcription profiles as the expression of a small and similar set of genes was affected by selection.