The transcriptomics of crushing jaw convergence in cichlid fishes: comparative gene expression in recent sympatric versus older allopatric trophic adaptations

How gene expression diverges during adaptation might be strongly influenced by the geographic setting and timeframe over which species evolve. To contrast transcriptomic patterns of replicate trophic adaptations that evolved convergently during both allopatric and sympatric contexts, we conducted RNA-seq on the trophically important lower pharyngeal jaws of two sympatrically and four allopatrically diverged species pairs of cichlid fishes. We first show that all of these species pairs have convergently diverged along a crushing trophic axis and that the sympatric pairs are as phenotypically divergent as the allopatric pairs. Then, we found that distinct sets of genes were differentially expressed in the jaws of sympatrically diverging pairs as compared to jaws in older allopatric species pairs. The genes that were differentially expressed in the jaws of allopatric pairs also were more highly expressed on average than in the sympatric pairs. Finally, for genes that were differentially ex...物种在适应过程中的基因表达分化模式，或受其演化所处的地理背景与时间跨度的强烈调控。为对比异域（allopatric）与同域（sympatric）背景下趋同演化的重复营养适应性的转录组特征差异，我们对2对同域分化、4对异域分化的丽鱼科鱼类（cichlid fishes）的营养功能核心器官——下咽颌开展了RNA测序（RNA-seq）。研究首先证实，所有受试物种对均沿压碎型营养轴发生趋同分化，且同域分化物种对的表型分化程度与异域分化物种对并无显著差异；随后我们发现，相较于较古老的异域物种对的下咽颌，同域分化物种对的下咽颌中差异表达的基因集存在明显差异，且异域物种对下咽颌内的差异表达基因的平均表达水平亦高于同域物种对；最后，针对差异表达……