一种新的DNA序列进化距离及其应用

A New Evolution Distance of DNA Sequence and Its Application

为了研究核苷酸变异,通过DNA序列的同源率,建立了DNA序列进化的动力学方程,进而得到了一种新的物种间进化距离dy(选择进化距离).由于核苷酸替代模型有很多,选用其中的4种模型,计算出其相应的选择进化距离dy,该进化距离包含了4种模型下的p距离、替代率为常数的距离d和替代率服从Г分布的Г距离dG.进一步根据动力学方程的特点,将模型转化为一元线性回归问题,用最小二乘法求得选择模型中的动力学参数b和各核苷酸位点每年的平均替代速率r.以16个物种的线粒体基因序列为例,说明这种新的进化距离并通过构建不同进化距离下的基因进化树来对各进化距离进行比较.结果表明:选择进化距离dy是一种有效的构建进化距离的方法.

In order to study the variation,dynamic equation of DNA sequences was established by the homology in nucleotide sequences,and further evolution distance dy（selected evolutionary distance） between species was obtained.Selected evolutionary distance dy was calculated in 4 nucleotide substitution models,and indicated the relationship among p-distance,d-distance and Г distance dG.According to the characteristics of dynamic equations,selection model can be transformed into a linear regression problem.Then both of the parameter b and the average substitution ratio of nucleotide each year r were obtained by the Least Square Method.Take the mitochondrial DNA sequences of 16 species for example to illustrate the new evolution distance,and then evolution trees are constructed in order to compare different evolution distance.The results indicate that the new distance dy is an efficient evolution distance to analyze DNA sequence.