Extensive introgression of mitochondrial DNA relative to nuclear genes in the Drosophila yakuba species group
Extensive introgression of mitochondrial DNA relative to nuclear genes in the Drosophila yakuba species group
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DOI：
10.1111/j.0014-3820.2006.tb01107.x
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发表时间：
2006-02-01
期刊：
影响因子：
3.3
通讯作者：
Andolfatto, P
中科院分区：
文献类型：
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作者：
Bachtrog, D;Thornton, K;Andolfatto, P
对最近分化的物种之间的基因流动的研究可以阐明自然选择在新物种形成中的作用。果蝇（Drosophila santomea）和D.雅库巴是最近分化的，部分生殖隔离的物种，继续在野外杂交，似乎是生殖隔离从更远的相关物种D。teissieri我们研究了这三个物种在多个X连锁，Y连锁和线粒体标记的核苷酸多态性和分歧的模式。所有这三个物种的变异性大大降低Y染色体相对于X，预期的nonrecombining染色体变异减少选择。这三个物种通常分化良好的核标记，几乎没有证据表明最近渗入的X或Y连锁基因。基于核基因的分析，我们估计D. santomea和D. yakuba在大约150万年前从D.大约一百万年前。与核基因座的模式相反，这三个物种都有一个非常相似的mtDNA单倍型。我们表明，线粒体DNA必须最近渗入跨越种间界限的D。yakuba亚群，其固定是由线粒体本身或其他细胞质因子的选择驱动的。这些结果表明，基因组的不同区域在物种形成的背景下可以有不同的进化动力学。虽然自然选择通常被认为是强调物种之间的分歧，我们的研究结果意味着它也可以作为一种竞争力。
Studies of gene flow between recently diverged species can illuminate the role of natural selection in the formation of new species. Drosophila santomea and D. yakuba are recently diverged, partially reproductively isolated species that continue to hybridize in the wild, and appear to be reproductively isolated from the more distantly related species D. teissieri. We examine patterns of nucleotide polymorphism and divergence in these three species at multiple X-linked, Y-linked, and mitochondrial markers. All three species harbor drastically reduced variability on the Y chromosome relative to the X, as expected for a nonrecombining chromosome subject to variation-reducing selection. The three species are generally well differentiated at the nuclear markers, with little evidence for recent introgression for either the X- or Y-linked genes. Based on the nuclear genes, we estimate that D. santomea and D. yakuba diverged about one-half million years ago and split from D. teissieri about one million years ago. In contrast to the pattern at nuclear loci, all three species share a very similar mtDNA haplotype. We show that the mtDNA must have recently introgressed across species boundaries in the D. yakuba subgroup and that its fixation was driven by either selection on the mitochondria itself or other cytoplasmic factors. These results demonstrate that different regions of the genome can have distinct evolutionary dynamics in the context of species formation. Although natural selection is usually thought of as accentuating divergence between species, our results imply that it can also act as a homogenizing force.