High-resolution genome-wide dissection of the two rules of speciation in Drosophila
High-resolution genome-wide dissection of the two rules of speciation in Drosophila
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DOI：
10.1371/journal.pbio.0050243
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发表时间：
2007-09-01
期刊：
影响因子：
9.8
通讯作者：
Presgraves, Daven C.
中科院分区：
文献类型：
--
作者：
Masly, John P.;Presgraves, Daven C.
合子后生殖隔离的特点是两个引人注目的经验模式。第一个是哈勒定律-异配子（XY）性别的物种杂种的优先不育或不育。第二个是所谓的大X效应--与常染色体的类似替换相比，一个物种的X染色体替换为另一个物种的X染色体对杂种适应度的影响不成比例地大。虽然第一条规则已经确立，但第二条规则仍然存在争议。在这里，我们剖析了这两个规则的遗传原因，使用全基因组的渐渗分析的果蝇mauritiana染色体片段，否则D。sechellia遗传背景。我们发现，隐性杂交不兼容的数量超过显性的和杂交雄性不育的数量超过所有其他类型的不兼容性，与Hallovan的规则的显性和快速男性理论，分别一致。我们还发现，虽然X连锁和常染色体基因渗入的大小相似，大多数X连锁基因渗入导致杂种雄性不育（60%），而很少的常染色体基因渗入（18%）。因此，我们的研究结果证实了大的X效应，并确定其近因：不相容性造成的杂交雄性不育有一个较高的密度比常染色体上的X染色体。我们评估了几种假说的进化原因，这种过度的X-连锁杂交雄性不育。
Postzygotic reproductive isolation is characterized by two striking empirical patterns. The first is Haldane's rule-the preferential inviability or sterility of species hybrids of the heterogametic (XY) sex. The second is the so-called large X effect-substitution of one species's X chromosome for another's has a disproportionately large effect on hybrid fitness compared to similar substitution of an autosome. Although the first rule has been well-established, the second rule remains controversial. Here, we dissect the genetic causes of these two rules using a genome-wide introgression analysis of Drosophila mauritiana chromosome segments in an otherwise D. sechellia genetic background. We find that recessive hybrid incompatibilities outnumber dominant ones and that hybrid male steriles outnumber all other types of incompatibility, consistent with the dominance and faster-male theories of Haldane's rule, respectively. We also find that, although X-linked and autosomal introgressions are of similar size, most X-linked introgressions cause hybrid male sterility (60%) whereas few autosomal introgressions do (18%). Our results thus confirm the large X effect and identify its proximate cause: incompatibilities causing hybrid male sterility have a higher density on the X chromosome than on the autosomes. We evaluate several hypotheses for the evolutionary cause of this excess of X-linked hybrid male sterility.