Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden.
Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden.
Genome Res. 2020 Dec;30(12):1727-1739. doi: 10.1101/gr.254508.119. Epub 2020 Nov 3.
Changes in interacting - and -regulatory elements are important candidates for Dobzhansky-Muller hybrid incompatibilities and may contribute to hybrid dysfunction by giving rise to misexpression in hybrids. To gain insight into the molecular mechanisms and determinants of gene expression evolution in natural populations, we analyzed the transcriptome from multiple tissues of two recently diverged flycatcher species and their naturally occurring F 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 misexpression in brain, heart, kidney, and liver. However, while testis showed the highest divergence of gene expression among tissues, it showed no clear signature of misexpression in F hybrids, even though these hybrids were found to be sterile. It is therefore unlikely that incompatibilities between - regulatory changes explain the observed sterility. Instead, we found evidence that -regulatory changes play a significant role in the evolution of gene expression in testis, which illustrates the tissue-specific nature of -regulatory evolution bypassing constraints associated with pleiotropic effects of genes.
互作调控元件的变化是 Dobzhansky-Muller 杂种不亲和性的重要候选者，可能通过在杂种中引发错误表达而导致杂种功能障碍。为了深入了解自然种群中基因表达进化的分子机制和决定因素，我们分析了两个最近分化的雀形目鸟类物种及其自然发生的 F1 杂种的多个组织的转录组。差异基因表达分析表明，物种间的分化程度和差异表达基因的集合在不同组织中存在差异。所有组织共有的是，与常染色体基因相比，Z 连锁基因的差异表达比例更高，这为快速 Z 效应提供了证据。我们进一步在大脑、心脏、肾脏和肝脏中发现了明显的杂种错误表达的迹象。然而，尽管睾丸在组织间表现出最高的基因表达分化，但在 F1 杂种中没有明显的错误表达迹象，尽管这些杂种被发现是不育的。因此，不太可能是 - 调控变化之间的不兼容性解释了观察到的不育性。相反，我们发现证据表明，- 调控变化在睾丸中基因表达的进化中起着重要作用，这说明了 - 调控进化的组织特异性，绕过了与基因多效性相关的约束。
