Rapid Rise and Fall of Selfish Sex-Ratio X Chromosomes in Drosophila simulans: Spatiotemporal Analysis of Phenotypic and Molecular Data
Rapid Rise and Fall of Selfish Sex-Ratio X Chromosomes in Drosophila simulans: Spatiotemporal Analysis of Phenotypic and Molecular Data
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DOI：
10.1093/molbev/msr074
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发表时间：
2011-09-01
影响因子：
10.7
通讯作者：
Montchamp-Moreau, Catherine
中科院分区：
文献类型：
--
作者：
Bastide, Heloise;Cazemajor, Michel;Montchamp-Moreau, Catherine
性别比驱动，已经在几个果蝇物种中被记录下来，是由X连锁的分离扭曲因子诱导的。与孟德尔的独立分类定律相反，性别比染色体(X-SR)由超过一半的携带者的后代遗传，导致性别比偏向女性。这种分离优势允许X-SR在人群中传播，即使这对携带者不利。在世界性物种中，巴黎的性别比是由最近出现的自私的X-SR染色体引起的。这些染色体引发了基因组内的冲突，由于完全驱动抑制的进化，它们的繁殖已经在很大程度上停止了。以前的分子群体遗传学分析显示，选择性扫描表明X-SR染色体在马达加斯加的入侵是最近的(可能不到100年前)。在这里，我们展示了X-SR染色体现在在这个位置以及在马约特和肯尼亚都在下降。在这三个群体中，驱动抑制是完全的，它们几乎没有遗传分化，共享扫描的单倍型，证明了X-SR染色体的一个共同的和非常近的祖先。DNA序列变异的模式也表明驱动过程中涉及的片段复制的适合性成本。数据表明，X-SR染色体首先在非洲大陆开始下降，然后在马约特，最后在马达加斯加，并强烈支持X染色体快速循环的情景。一旦驱动器抑制进化，在几十年内，标准的X-ST染色体就会局部取代昂贵的X-SR染色体。
Sex-ratio drive, which has been documented in several Drosophila species, is induced by X-linked segregation distorters. Contrary to Mendel's law of independent assortment, the sex-ratio chromosome (X-SR) is inherited by more than half the offspring of carrier males, resulting in a female-biased sex ratio. This segregation advantage allows X-SR to spread in populations, even if it is not beneficial for the carriers. In the cosmopolitan species D. simulans, the Paris sex-ratio is caused by recently emerged selfish X-SR chromosomes. These chromosomes have triggered an intragenomic conflict, and their propagation has been halted over a large area by the evolution of complete drive suppression. Previous molecular population genetics analyses revealed a selective sweep indicating that the invasion of X-SR chromosomes was very recent in Madagascar (likely less than 100 years ago). Here, we show that X-SR chromosomes are now declining at this location as well as in Mayotte and Kenya. Drive suppression is complete in the three populations, which display little genetic differentiation and share swept haplotypes, attesting to a common and very recent ancestry of the X-SR chromosomes. Patterns of DNA sequence variation also indicate a fitness cost of the segmental duplication involved in drive. The data suggest that X-SR chromosomes started declining first on the African continent, then in Mayotte, and finally in Madagascar and strongly support a scenario of rapid cycling of X chromosomes. Once drive suppression has evolved, standard X-ST chromosomes locally replace costly X-SR chromosomes in a few decades.