Science2014-07-01 3:31 PM

为什么在相互无关的鱼中会出现相同的电器官 Genomic basis for the convergent evolution of electric organs

论文摘要 

据一项新的研究报告,鱼用于导航及通讯的电器官——它们让科学家们感到困惑,因为它们一再地出现于相互没有关系的鱼类中——在其宿主体内进行演化,因为特定的发育通路在每种鱼中发生了改变。Jason Gallant及其同事组装了电鳗的基因组。为了帮助理解在电器官或EOs中表达的基因的演化,研究人员对来自3种独立演化出这些电击器官的鱼谱系的EO组织中的RNA产物进行了测序。它们中包括了电鲇——它与其它谱系一样,在某一独特的路径上演化了数百万年之久。研究人员发现,尽管它们有着不同的进化轨迹,但是这些谱系共有相似的基因表达模式。在每一谱系中,与肌肉中导引电流有关的基因表达有所增加,而与将电刺激转化为肌肉收缩——这种活动在电器官中并不那么需要——的基因表达则有所减少。Gallant及其同事的工作提示,某种共同的基因调节网络被自然选择反复地作为标靶,从而塑造了需要有电器官才能生存的生物中的电器官的发育。它可帮助解释导致趋同进化的遗传机制。

Abstract 

Little is known about the genetic basis of convergent traits that originate repeatedly over broad taxonomic scales. The myogenic electric organ has evolved six times in fishes to produce electric fields used in communication, navigation, predation, or defense. We have examined the genomic basis of the convergent anatomical and physiological origins of these organs by assembling the genome of the electric eel (Electrophorus electricus) and sequencing electric organ and skeletal muscle transcriptomes from three lineages that have independently evolved electric organs. Our results indicate that, despite millions of years of evolution and large differences in the morphology of electric organ cells, independent lineages have leveraged similar transcription factors and developmental and cellular pathways in the evolution of electric organs.

Editor's Summary

Only one way to make an electric organ?

Electric fish have independently evolved electric organs that help them to communicate, navigate, hunt, and defend themselves. Gallant et al. analyzed the genome of the electric eel and the genes expressed in two other distantly related electric fish. The same genes were recruited within the different species to make evolutionarily new structures that function similarly.

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