EVOLUTIONARY IMPLICATIONS OF DNA DIVERGENCE IN THE DROSOPHILA-OBSCURA GROUP
EVOLUTIONARY IMPLICATIONS OF DNA DIVERGENCE IN THE DROSOPHILA-OBSCURA GROUP
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DOI：
10.1111/j.1558-5646.1990.tb03854.x
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发表时间：
1990-09-01
期刊：
影响因子：
3.3
通讯作者：
POWELL, JR
中科院分区：
文献类型：
--
作者：
GODDARD, K;CACCONE, A;POWELL, JR
使用DNA-DNA杂交，我们已经确定的程度，单拷贝DNA（scDNA）的分歧之间的8种果蝇obscura组。这些包括旧世界和新世界物种以及两个亚组的成员。与经典的系统学相反，affinis亚组的成员与暗子组的美洲成员的关系比旧世界物种更密切。旧大陆的物种不是一个单系群。物种间scDNA分歧的程度不一定与形态学、染色体分歧或形成杂种的能力相关。发现了杂交体形成的独特模式：由6.5 ° Δ Tm分离的物种。C可以形成杂交体，而由2.5 ° Δ Tm分离的物种可以形成杂交体。C不能。与果蝇的其他类群一样，暗果蝇类群的基因组各部分的进化速度非常不同。核基因组中进化缓慢的部分以与线粒体DNA相同的速度进化。伴随着从部分生殖隔离（在北美伪暗虫和隔离的波哥大[哥伦比亚]种群之间）到完全隔离的步骤的额外scDNA分歧非常小。该技术的分辨率受到五个密切相关的分类群的挑战，其最大Δ Tm为2.5 °。C分离它们;分类群被明确地解决和“正确的”恢复。最后，有一些迹象表明，暗组中的scDNA可能比黑腹亚组中的进化慢得多。
Using DNA-DNA hybridization, we have determined the degree of single-copy DNA (scDNA) divergence among eight species of the Drosophila obscura group. These include Old World and New World species as well as members of two subgroups. Contrary to classical systematics, members of the affinis subgroup are more closely related to American members of the obscura subgroup than are Old World species. The Old World species are not a monophyletic group. The degree of scDNA divergence among species is not necessarily correlated with morphology, chromosomal divergence, or ability to form hybrids. A unique pattern of hybrid formation was found: species separated by a .DELTA.Tm of 6.5.degree. C can form hybrids whereas species separated by a .DELTA.Tm of 2.5.degree. C cannot. As with other groups of Drosophila, the obscura group has discrete parts of the genome evolving at very different rates. The slow evolving fraction of the nuclear genome is evolving at about the same rate as mitochondrial DNA. The additional scDNA divergence accompanying the step from partial reproductive isolation (between North American pseudoobscura and the isolated Bogota, [COLOMBIA] population) to full isolation is very small. The resolution of the technique was challenged by five closely related taxa with a maximum .DELTA.Tm of 2.5.degree. C separating them; the taxa were unambiguously resolved and the "correct" phylogeny recovered. Finally, there is some indication that scDNA in the obscura group may be evolving considerably slower than in the melanogaster subgroup.