Centromere-proximal differentiation and speciation in Anopheles gambiae.
Centromere-proximal differentiation and speciation in Anopheles gambiae.
复制标题
冈比亚按蚊的着丝粒近端分化和物种形成。
DOI：
10.1073/pnas.0508161102
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发表时间：
2005
影响因子：
11.1
通讯作者：
Besansky,NoraJ
中科院分区：
文献类型：
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作者：
Stump,AramD;Fitzpatrick,MeaganC;Lobo,NeilF;Traoré,Sékou;Sagnon,N'Fale;Costantini,Carlo;Collins,FrankH;Besansky,NoraJ
冈比亚按蚊的M和S分子形式正在经历物种形成，因为它们适应了环境中的异质性，在此过程中传播疟疾。我们假设，尽管基因流，他们的分歧是促进减少重组在着丝粒（近端）的X染色体。我们测序内含子从22个X染色体基因在M和S从两个地点的西非的形式是同域的。一般来说，在这两种形式的核苷酸多样性是高远端，较低的近端，和非常低的最近的着丝粒。相反，形式之间的差异几乎为零远端和非常高的近端。与近亲阿拉伯按蚊（Anopheles arabiensis）的成对比较显示，无论X染色体沿着的位置如何，都表现出一致的高分歧，这表明这种模式不是纯粹的机械性的。相反，对M和S观察到的模式表明，趋异的自然选择只在X染色体的近端对抗基因流动，在那里重组减少。M和S之间具有固定差异的位点与A中相应位点的比较。arabiensis的研究表明，衍生的取代在两种形式中都是固定的，进一步支持了两者都处于选择之下的假设。这些衍生的替代是固定在两个西非样品和样品的S从西部和沿海肯尼亚，这表明选择发生之前的形式扩大到目前的范围。我们的研究结果是一致的作用，抑制遗传重组的物种形成ofA。冈比亚。
The M and S molecular forms ofAnopheles gambiaeare undergoing speciation as they adapt to heterogeneities in the environment, spreading malaria in the process. We hypothesized that their divergence despite gene flow is facilitated by reduced recombination at the centromeric (proximal) end of the X chromosome. We sequenced introns from 22 X chromosome genes in M and S from two locations of West Africa where the forms are sympatric. Generally, in both forms nucleotide diversity was high distally, lower proximally, and very low nearest the centromere. Conversely, differentiation between the forms was virtually zero distally and very high proximally. Pairwise comparisons to a close relative, the sibling speciesAnopheles arabiensis, demonstrated uniformly high divergence regardless of position along the X chromosome, suggesting that this pattern is not purely mechanical. Instead, the pattern observed for M and S suggests the action of divergent natural selection countering gene flow only at the proximal end of the X chromosome, where recombination is reduced. Comparison of sites with fixed differences between M and S to the corresponding sites inA. arabiensisrevealed that derived substitutions had been fixed in both forms, further supporting the hypothesis that both have been under selection. These derived substitutions are fixed in the two West African samples and in samples of S from western and coastal Kenya, suggesting that selection occurred before the forms expanded to their current ranges. Our findings are consistent with a role for suppressed genetic recombination in speciation ofA. gambiae.