Abstract

Genetic divergence and evolutionary shift of transitions and transversions ratio were analyzed based on examples of 60 sequences of the mtDNA control region of 27 species of mice (Murinae) of the Palearctic region. Representatives of Cricetidae and Arvicolidae were taken as outgroups. The constructed phenogram corresponds to the accepted phylogenetic scheme and is clustered according to population, semispecies, allospecies, species, genus and family levels of divergence. In the phyletic order there is a clearly defined evolutionary transition/transversion rate bias. Its distinction is an extremely fast and abrupt transition from dynamic to stable phase. The dynamic phase is a rapid decrease in the ti/tv rate ratio and refers to the population and semispecies divergence levels. The stable phase refers to the species level and higher divergence levels and is associated with reaching a state of genetic saturation in a situation of predominance of transversions. The extreme denotion of the evolutionary shift in the D-loop case can be explained by the removal of the selection pressure caused by restrictions in amino acid substitutions. This means that the causes of transition/transversion bias are purely biochemical mechanisms on DNA level. Simultaneously, the stability of the ti/tv ratio at species and higher levels amidst the further accumulation of the total number of nucleotide substitutions may indicate a fundamentally different nature of genetic processes at the intraspecies and interspecies levels of divergence.

中文翻译：

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古北极小鼠 (Murinae) 线粒体 DNA 控制区的遗传分化和进化转换/转化率偏差

摘要

以古北极地区27种小鼠(鼠亚科)的mtDNA控制区60条序列为例，分析了遗传分化和转换和颠换率的进化转移。Cricetidae 和 Arvicolidae 的代表被视为外群。构建的表型对应于公认的系统发育方案，并根据种群、半种、异种、种、属和科的分歧水平进行聚类。在系统顺序中，有一个明确定义的进化过渡/颠换率偏差。它的特点是从动态阶段到稳定阶段的非常快速和突然的转变。动态阶段是 ti/tv 比率的快速下降，指的是种群和半种分化水平。稳定阶段是指物种水平和更高的分歧水平，并且与在颠换占优势的情况下达到遗传饱和状态有关。D-loop 案例中进化转变的极端含义可以通过消除氨基酸取代限制引起的选择压力来解释。这意味着转换/颠换偏差的原因纯粹是 DNA 水平上的生化机制。同时，在核苷酸取代总数的进一步积累中，物种和更高水平的 ti/tv 比率的稳定性可能表明在种内和种间差异水平上遗传过程的根本不同性质。