The speciation history of the Drosophila nasuta complex
The speciation history of the Drosophila nasuta complex
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DOI：
10.1017/s0016672306008330
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发表时间：
2006-08-01
影响因子：
1.5
通讯作者：
Bachtrog, Doris
中科院分区：
文献类型：
--
作者：
Bachtrog, Doris
迁徙种群中的纳苏塔果蝇亚群广泛分布于东南亚地区，由形态相似但生殖隔离程度不同的物种组成。在这里，我报告了来自纳苏塔亚群的8个分类群的5个x连锁位点和2个mtDNA位点的核苷酸变异数据，并从D. albomicans及其姊妹物种纳苏塔D.纳苏塔进行了更深入的采样。这些物种之间的系统发育关系因不同的基因组区域而异，遗传分化水平表明，这一物种群在大约100万年前才开始多样化。D. albomicans和D. nasuta共享核苷酸多态性，并以相对较少的固定差异区分。这对物种之间的遗传分化模式与没有基因流动的简单分离模型是相容的。纳苏塔属物种的核苷酸变异水平与黑腹鱼和伪腹鱼属物种相当，表明有效种群规模约为数百万。群体遗传分析结果表明，对白斑田鼠和纳苏塔田鼠中性多态性频率分布的总结大体上符合标准中性模型的假设。由于其最近形成的新性染色体，因此对进化研究特别感兴趣，我们的系统发育和群体遗传分析表明，它可能是研究Y染色体早期进化阶段的理想模型。
The Drosophila nasuta subgroup of the immigrans species group is widely distributed throughout the South-East Asian region, consisting of morphologically similar species with varying degrees of reproductive isolation. Here, I report nucleotide variability data for five X-linked and two mtDNA loci in eight taxa from the nasuta subgroup, with deeper sampling from D. albomicans and its sister species D. nasuta. Phylogenetic relationships among these species vary among different genomic regions, and levels of genetic differentiation suggest that this species group diversified only about one million years ago. D. albomicans and D. nasuta share nucleotide polymorphisms and are distinguished by relatively few fixed differences. Patterns of genetic differentiation between this species pair are compatible with a simple isolation model with no gene flow. Nucleotide variability levels of species in the nasuta group are comparable to those in members of the melanogaster and pseudoobscura species groups, indicating effective population sizes on the order of several million. Population genetic analyses reveal that summaries of the frequency distribution of neutral polymorphisms in both D. albomicans and D. nasuta generally fit the assumptions of the standard neutral model. D. albomicans is of particular interest for evolutionary studies because of its recently formed neo-sex chromosomes, and our phylogenetic and population genetic analyses suggest that it might be an ideal model to study the very early stages of Y chromosome evolution.