Run or Die in the Evolution of New MicroRNAs—Testing the Red Queen Hypothesis on De Novo New Genes

Abstract The Red Queen hypothesis depicts evolution as the continual struggle to adapt. According to this hypothesis, new genes, especially those originating from nongenic sequences (i.e., de novo genes), are eliminated unless they evolve continually in adaptation to a changing environment. Here, we analyze two Drosophila de novo miRNAs that are expressed in a testis-specific manner with very high rates of evolution in their DNA sequence. We knocked out these miRNAs in two sibling species and investigated their contributions to different fitness components. We observed that the fitness contributions of miR-975 in Drosophila simulans seem positive, in contrast to its neutral contributions in D. melanogaster, whereas miR-983 appears to have negative contributions in both species, as the fitness of the knockout mutant increases. As predicted by the Red Queen hypothesis, the fitness difference of these de novo miRNAs indicates their different fates.

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Run or die in the evolution of new microRNAs - Testing the Red Queen hypothesis on de novo new genes

10.1101/345769 ◽

2018 ◽

Cited By ~ 2

Author(s):

Yixin Zhao ◽

Guang-An Lu ◽

Hao Yang ◽

Pei Lin ◽

Zhongqi Liufu ◽

...

Keyword(s):

De Novo ◽

Red Queen Hypothesis ◽

Knockout Mutant ◽

Red Queen ◽

Fitness Components ◽

New Genes ◽

Rates Of Evolution ◽

Specific Manner ◽

The Red Queen ◽

Very High

AbstractThe Red Queen hypothesis depicts evolution as the continual struggle to adapt. According to this hypothesis, new genes, especially those originating from non-genic sequences (i.e., de novo genes), are eliminated unless they evolve continually in adaptation to a changing environment. Here, we analyze two Drosophila de novo miRNAs that are expressed in a testis-specific manner with very high rates of evolution in their DNA sequence. We knocked out these miRNAs in two sibling species and investigated their contributions to different fitness components. We observed that the fitness contributions of miR-975 in D. simulans seem positive, in contrast to its neutral contributions in D. melanogaster, while miR-983 appears to have negative contributions in both species, as the fitness of the knockout mutant increases. As predicted by the Red Queen hypothesis, the fitness difference of these de novo miRNAs indicates their different fates.

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Mechanisms of gene death in the Red Queen race revealed by the analysis ofde novomicroRNAs

10.1101/349217 ◽

2018 ◽

Author(s):

Guang-An Lu ◽

Yixin Zhao ◽

Ao Lan ◽

Zhongqi Liufu ◽

Haijun Wen ◽

...

Keyword(s):

De Novo ◽

Mirna Gene ◽

Red Queen ◽

Fitness Effects ◽

New Genes ◽

Knockout Mutants ◽

Laboratory Populations ◽

The Many ◽

The Red Queen

AbstractThe prevalence ofde novocoding genes is controversial due to the length and coding constraints. Non-coding genes, especially small ones, are freer to evolvede novoby comparison. The best examples are microRNAs (miRNAs), a large class of regulatory molecules ~22 nt in length. Here, we study 6de novomiRNAs inDrosophilawhich, like most new genes, are testis-specific. We ask how and whyde novogenes die because gene death must be sufficiently frequent to balance the many new births. By knocking out each miRNA gene, we could analyze their contributions to each of the 9 components of male fitness (sperm production, length, competitiveness etc.). To our surprise, the knockout mutants often perform better in some components, and slightly worse in others, than the wildtype. When two of the younger miRNAs are assayed in long-term laboratory populations, their total fitness contributions are found to be essentially zero. These results collectively suggest that adaptivede novogenes die regularly, not due to the loss of functionality, but due to the canceling-out of positive and negative fitness effects, which may be characterized as “quasi-neutrality”. Sincede novogenes often emerge adaptively and become lost later, they reveal ongoing period-specific adaptations, reminiscent of the “Red-Queen” metaphor for long term evolution.

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