Tissue-specific patterns of regulatory changes underlying gene expression differences among Ficedula flycatchers and their naturally-occurring F1 hybrids [RESEARCH]

Changes in interacting cis- and trans-regulatory elements are important candidates for Dobzhansky-Muller hybrid incompatibilities and may contribute to hybrid dysfunction by giving rise to mis-expression in hybrids. To gain insight into the molecular mechanisms and determinants of gene expression evolution in natural populations, we analysed the transcriptome from multiple tissues of two recently diverged Ficedula flycatcher species and their naturally-occurring F1 hybrids. Differential gene expression analysis revealed that the extent of differentiation between species and the set of differentially expressed genes varied across tissues. Common to all tissues, a higher proportion of Z-linked genes than autosomal genes showed differential expression, providing evidence for a fast-Z effect. We further found clear signatures of hybrid mis-expression in brain, heart, kidney and liver. However, while testis showed the highest divergence of gene expression among tissues, it showed no clear signature of mis-expression in F1 hybrids, even though these hybrids were found to be sterile. It is therefore unlikely that incompatibilities between cis-trans regulatory changes explain the observed sterility. Instead, we found evidence that cis-regulatory changes play a significant role in the evolution of gene expression in testis, which illustrates the tissue-specific nature of cis-regulatory evolution bypassing constraints associated with pleiotropic effects of genes.

Source: Genome Research - November 3, 2020 Category: Genetics & Stem Cells Authors: Mugal, C. F., Wang, M., Backstrom, N., Wheatcroft, D., Alund, M., Semon, M., McFarlane, S. E., Dutoit, L., Qvarnstrom, A., Ellegren, H. Tags: RESEARCH Source Type: research