Regulation of gene expression is thought to play a major role in adaptation but the relative importance of cis- and trans- regulatory mechanisms in the early stages of adaptive divergence is unclear. Using RNAseq of threespine stickleback fish gill tissue from four independent marine-freshwater ecotype pairs and their F1 hybrids, we show that cis-acting (allele-specific) regulation consistently predominates gene expression divergence. Genes showing parallel marine-freshwater expression divergence are found near to adaptive genomic regions, show signatures of natural selection around their transcription start sites and are enriched for cis-regulatory control. For genes with parallel increased expression among freshwater fish, the quantitative degree of cis- and trans-regulation is also highly correlated across populations, suggesting a shared genetic basis. Compared to other forms of regulation, cis-regulation tends to show greater additivity and stability across different genetic and environmental contexts, making it a fertile substrate for the early stages of adaptive evolution.
- Felicity C Jones
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: All of the animals were housed at an approved animal facility and handled according to Baden-Württemberg State approved protocols at the Max Planck Institute for Developmental Biology, Tübingen, Germany (license numbers 35/9185.82-5 and 35/9185.40).
- Juliette de Meaux, University of Cologne, Germany
© 2019, Verta & Jones
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