Cryptic Speciation and Characteristics of the Transition Bias Following an Example of the cytb Gene in Palearctic Mammals

Abstract

A study of taxonomic differentiation and transition bias of the cytb gene, focusing on the early stages of speciation, was carried out in 15 subfamilies/families of five orders of Palearctic mammals. It was confirmed that the genetic differentiation among taxa of small and large mammals is shifted by the same taxonomic level, in which connection the period of cryptic speciation of Micromammalia (semi- and allospecific levels) corresponds to the divergence of type species in their genus within Macromammalia. In all cases, both transition bias and its evolutionary compensation took place. The novelty of the study also lies in the proof that the alignment of the transitions and transversion rates in evolutionary lineages has the pattern of a phase transition, and the frequency of transversions in short-cycle species of the orders Insectivora and Rodentia is higher than in long-cycle orders Artiodactyla, Carnivora and Chiroptera while with relative equality of transitions. The latter circumstance might be associated with the traits of metabolism and determines the characteristics of the molecular evolution of mammalian groups with short and long life cycles.