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 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 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 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 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.

中文翻译：

---

Ficedula 捕蝇器及其自然发生的 F1 杂种之间基因表达差异背后的组织特异性调节变化模式

相互作用的顺式和反式调节元件的变化是 Dobzhansky-Muller 杂种不相容性的重要候选者，并且可能通过引起杂种中的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，我们分析了来自两个最近分化的Ficedula flycatcher 物种及其天然存在的 F _{1 的}多个组织的转录组杂种。差异基因表达分析表明，物种之间的分化程度和差异表达的基因组因组织而异。对于所有组织来说，Z-连锁基因的比例高于常染色体基因的差异表达，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混合错误表达的明显特征。然而，虽然睾丸在组织中表现出最大的基因表达差异，但在 F ₁杂种中没有显示出明显的错误表达特征，即使这些杂种被发现是不育的。因此，顺式-反式之间的不相容性不太可能监管变化解释了观察到的不育。相反，我们发现了顺式调节变化在睾丸基因表达进化中起重要作用的证据，这说明顺式调节进化绕过与基因多效性效应相关的限制的组织特异性性质。