核酸序列进化的早期突涨模型

总结了序列编码区的统计特征。1.信息参致(?)X对进化的依赖;2.关联长度的分布;3.子序列参数的特异性;4.编码区长度与进化水平无关;5.重复区长度的冻结现象;6.重复片段具有大的D_f和偏置的GC含量。为了解释这些特征,本文提出假设:生命形成伊始,有一个序列长度的突涨阶段一一序列(编码区)在较短的时间内,通过重复,拼接而迅速变长。当序列达到了一定长度以后,才开始以碱基突变和选择为主的阶段,以及真核以后的内含子插入机制阶段。

The Inflation Model of Evolution of Nucleic Acid Sequences

The statistical characteristics of the coding region of nucleie acid sequences are reviewed. They are: 1, the dependence of evolution on D_1, D_2 and X ; 2, the distribution of correlation length; 3, the specific feature of subsequence parameters; 4, the independence of length on evolution; 5, the frozen ratio of total length of repeated segments; 6, the large D_1 and biased GC content in repeated segments. To explain these characteristics it is supposed that in the early epoch of molecular evolution there exists an inflation stage. That is, in relatively short time the sequence is enlarged through repeatition and linkage of small segments. Only after a definite length of sequence is reached a new stage of evolution could begin which is dominated by base mutation and selection.