ABSTRACT: Sequencing a normalized cDNA library to study the effect of natural selection on sequence evolution in the brook charr, Salvelinus fontinalis
Project description:Domestication has been practiced for centuries yet directed towards 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 ~ 32 000 cDNA features performed in both a 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 5-7 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 were affected by selection.
Project description:Salvelinus Microarray experiment: The influence of parental effects on transcriptomic landscape during early development in brook charr (Salvelinus fontinalis, Mitchill)
Project description:Domestication has been practiced for centuries yet directed towards 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 ~ 32 000 cDNA features performed in both a 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 5-7 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 were affected by selection. Two conditions environment: direct comparison of control vs domesticated fish for 20 families. No individual replicates but two individuals of the same family were hybridized on different slides
Project description:Directional selection in the domestication of fish species has resulted in rapid gains of growth, body size, and other production-relevant traits in relatively few generations. While there is clear evidence of genetic divergence contributing to selection-related phenotypic changes, emerging research suggests that intergenerational epigenetic inheritance may also be a relevant mechanism explaining rapid evolutionary change in domestic fish lines. Epigenetic changes have also been implicated in fish species’ responses to warming associated with climate change. Domestic lines of Brook Charr (Salvelinus fontinalis) are the primary source of fish used for recreational fisheries stocking in many parts of Eastern North America and there are concerns about how these fish will fare when stocked into lakes in the coming decades. We jointly investigated the effects of directional selection for performance traits (i.e., absence of early sexual maturation and increased growth) and exposure to elevated temperatures on DNA methylation in sperm cells of two experimental lines (hereafter: Selected and Control lines) of Brook Charr . We used whole-genome bisulfite sequencing to characterize DNA methylation at over 17 million methylated sites and identified 393 selection-related differentially methylated regions (DMR). The putative functions of genes in proximity to these DMRs are consistent with well-characterized phenotypic differences between the lines, including lipid metabolism and precocial maturation, and support the hypothesis that rapid evolution of traits may be partially mediated by epigenetic inheritance. We subsequently detected 85 warming-related DMRs in the Control line and 302 DMRs in the Selected line. None of these regions were shared between the two lines, indicating that the directional selection regime significantly altered the environmentally sensitive epigenetic landscape.