Multilocus analysis of introgression between two sympatric sister species of Drosophila:: Drosophila yakuba and D. santomea
Multilocus analysis of introgression between two sympatric sister species of Drosophila:: Drosophila yakuba and D. santomea
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DOI：
10.1534/genetics.104.033597
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发表时间：
2005-09-01
期刊：
影响因子：
3.3
通讯作者：
Coyne, JA
中科院分区：
文献类型：
--
作者：
Llopart, A;Lachaise, D;Coyne, JA
Yakuba果蝇广泛分布于撒哈拉以南非洲，而D.桑托梅是加蓬以西280公里的大西洋火山岛桑托梅的特有种。On Sao托姆，D.雅库巴主要分布在开阔的低地森林中，而D. santomea仅限于海拔较高的潮湿迷雾森林。在中间海拔，该物种形成一个杂交区，其中杂交种的发生频率接近1%。为了确定这些物种之间的基因流动程度，我们研究了分布在整个基因组中的29个区域的多态性和分歧模式，包括mtDNA和Y染色体上的三个基因。这种多位点的方法，以及与两个异地种D。mauritiana和D. sechellia，允许我们区分应该影响所有基因的力和应该作用于某些基因的力（例如，基因渗入）。结果表明，D. yakuba mtDNA取代了D. santomea，并且两个核基因yellow和salr也存在显著的渐渗。然而，大多数基因仍然不同。因此，这两个物种不会形成一个“杂交群”，其中大部分基因组显示出大量的基因渗入，而破坏性选择仅保持少数性状的独特性（例如，色素沉着和男性生殖器）。
Drosophila yakuba is widely distributed in sub-Saharan Africa, while D. santomea is endemic to the volcanic island of SaoTome in the Atlantic Ocean, 280 km west of Gabon. On Sao Tome, D. yakuba is found mainly in open lowland forests, and D. santomea is restricted to the wet misty forests at higher elevations. At intermediate elevations, the species form a hybrid zone where hybrids occur at a frequency of similar to 1%. To determine the extent of gene flow between these species we studied polymorphism and divergence patterns in 29 regions distributed throughout the genome, including mtDNA and three genes on the Y chromosome. This multilocus approach, together with the comparison to the two allopatric species D. mauritiana and D. sechellia, allowed us to distinguish between forces that should affect allgenes and forces that should act on some genes (e.g., introgression). Our results show that D. yakuba mtDNA has replaced that of D. santomea and that there is also significant introgression for two nuclear genes, yellow and salr. The majority of genes, however, has remained distinct. These two species therefore do not form a "hybrid swarm" in which much of the genome shows substantial introgression while disruptive selection maintains distinctness for only a few traits (e.g., pigmentation and male genitalia).