DNA Hybridization Comparison of Mitochondrial Versus NuclearDNA Evolution in Birds

线粒体DNA （mitochondrial DNA, mtDNA）以其简单、进化速度快的特点，在鸟类系统学中发挥着越来越重要的作用。然而，尽管mtDNA具有巨大的潜力，但它在鸟类问题中的应用在很大程度上取决于从哺乳动物mtDNA中推断出来的进化假设。虽然鸟类mtDNA进化的初始速度似乎很快，但尚不清楚它们是否与哺乳动物相同。此外，越来越多的证据表明，鸟类的mtDNA饱和平台可能低于哺乳动物，这意味着鸟类和哺乳动物之间在某些程度上的差异。结果是，我们在不知道比率模式如何影响这些估计的情况下，得出了鸟类遗传差异的数据。在本项目中，mtDNA和单拷贝核（scn） DNA杂交将被用于估计飞燕科（燕子）和飞燕科（山雀和山雀）的系统发育和选定的非雀形目分类群之间的差异。DNA杂交特别适合于这种分析，因为它可以测量小的mt和大的scn基因组在分类群之间的总体差异，并以单一的数据形式呈现它们。然后，这些数据可以被绘制出来，而不需要转换或参考化石年代，来描绘相对的速率和饱和度水平。dna杂交系统发育也将相互比较，并与广泛的限制性片段分析结果进行比较，以评估各种类型的系统发育数据。

By virtue of its simplicity and fast rate of evolution, mitochondrial DNA (mtDNA) is playing an increasingly important role in avian systematics. Yet despite its great potential, the application of mtDNA to avian problems depends heavily upon evolutionary assumptions extrapolated from mammal mtDNAs. While initial rates of bird mtDNA evolution appear to be fast, it is unknown whether they are the same as in mammals. Further, evidence is accruing that the mtDNA saturation plateau in birds may be lower than in mammals, which implies a difference between bird and mammal rates at some levels of divergence. The upshot is that we are producing data on avian genetic divergences without knowing how rate patterns are influencing those estimates. In this project, mtDNA and single-copy nuclear (scn) DNA hybridization will be employed to estimate phylogenies of the Hirundinidae (swallows) and Paridae (chickadees and titmice) and divergences among selected non-passerine taxa. DNA hybridization is especially appropriate for such analyses because it can measure overall divergence among taxa for both the small mt and huge scn genomes, and present them in a single data form. These data can then be plotted, without conversion or reference to fossil datings, to depict relative rates and saturation levels. DNA-hybridization phylogenies will also be compared to one another and to results of extensive restriction fragment analyses to assess the various types of phylogenetic data.