Hybridization drives rapid speciation by shaping novel genotypic and phenotypic profiles. Genomic incompatibility and transcriptome shock have been observed in hybrids, although this is rarer in animals than in plants. Using the newly sequenced genomes of the blunt snout bream (Megalobrama amblycephala [BSB]) and the topmouth culter (Culter alburnus [TC]), we focused on the sequence variation and gene expression changes in the reciprocal intergeneric hybrid lineages (F1-F3) of BSB × TC. A genome-wide transcriptional analysis identified 145-974 expressed recombinant genes in the successive generations of hybrid fish, suggesting the rapid emergence of allelic variation following hybridization. Some gradual changes of gene expression with additive and dominance effects and various cis and trans regulations were observed from F1 to F3 in the two hybrid lineages. These asymmetric patterns of gene expression represent the alternative strategies for counteracting deleterious effects of the subgenomes and improving adaptability of novel hybrids. Furthermore, we identified positive selection and additive expression patterns in transforming growth factor, beta 1b (tgfb1b), which may account for the morphological variations of the pharyngeal jaw in the two hybrid lineages. Our current findings provide insights into the evolution of vertebrate genomes immediately following hybridization.

中文翻译：

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该亚基因组显示了Mallobrama amblycephala×Culter alburnus杂交谱系中等位基因的不对称表达。

杂交通过形成新的基因型和表型图谱来驱动快速的物种形成。在杂种中观察到基因组不相容和转录组休克，尽管在动物中比在植物中少见。使用钝嘴鲷（Megalobrama amblycephala [BSB]）和topmouth culter（Culter alburnus [TC]）的新测序基因组，我们着眼于相互的属间杂种谱系（F1-F3）的序列变异和基因表达变化BSB×TC。全基因组转录分析在杂交鱼的后代中鉴定出145-974个表达的重组基因，表明杂交后等位基因变异迅速出现。在两个杂种谱系中，从F1到F3观察到基因表达随加性和显性作用以及各种顺式和反式调节逐渐变化。这些基因表达的不对称模式代表了抵消亚基因组的有害影响并提高新型杂交体适应性的替代策略。此外，我们在转化生长因子beta 1b（tgfb1b）中确定了阳性选择和加性表达模式，这可能解释了两个杂交谱系中咽颌的形态变化。我们目前的发现提供了对杂交后脊椎动物基因组进化的见解。这些基因表达的不对称模式代表了抵消亚基因组的有害影响并提高新型杂交体适应性的替代策略。此外，我们在转化生长因子beta 1b（tgfb1b）中确定了阳性选择和加性表达模式，这可能解释了两个杂交谱系中咽颌的形态变化。我们目前的发现提供了对杂交后脊椎动物基因组进化的见解。这些基因表达的不对称模式代表了抵消亚基因组的有害影响并提高新型杂种适应性的替代策略。此外，我们在转化生长因子beta 1b（tgfb1b）中确定了阳性选择和加性表达模式，这可能解释了两个杂交谱系中咽颌的形态变化。我们目前的发现提供了对杂交后脊椎动物基因组进化的见解。