Background: The mitochondrial genome serves as a pivotal molecular marker for delving into systematic relationships and adaptive mechanisms. The genus Eothenomys (Cricetidae: Arvicolinae) has consistently attracted attention due to its similar biological characteristics and the analysis of its mitochondrial genome offers a fresh perspective for comprehending the phylogeny and adaptation within Cricetidae. 
 
Methods: We sequenced and analyzed the entire mitochondrial genome of E. olitor and utilized the 13 PCGs derived from this genome to delineate the phylogenetic relationships within the Cricetidae and further evaluated the evolutionary rate of each PCG. 
 
Result: The findings revealed that the mitochondrial genome of E. olitor was 16,351 bp in length, including 13 PCGs with ATN initiation codons, 22 tRNAs, 2 rRNAs and 1 D-loop. Apart from the nad6 and 8 tRNAs positioned on the J-strand, the majority of the genetic elements were situated on the N-strand. The phylogenetic examination yielded a robust phylogenetic tree for Cricetidae, but the placement of some genera remained contentious, which needs more integrative and effective data. Among of them, E. olitor was a sister of E. chinensis and Eothenomys was monophyletic. Moreover, a selective analysis showed that evolutionary rates are significant differences among the 13 PCGs. Among these genes, atp8 a high evolutionary rate, while cox1 has a low. This research uncovered the mitochondrial genome analysis of E. olitor, offering valuable perspectives the phylogeny and adaptation within Cricetidae.

Phylogenetic Insights from the Mitochondrial Genome of Eothenomys olitor (Thomas, 1911): A Cricetidae Perspective

Background: Animal body color was crucial for genetics and evolution, among which albinism was the result of genetic mutations and there were multiple genetic mechanisms that impede melanin synthesis, thereby affecting animal survival. Studying the phenomenon of albinism could help deepen our understanding of the secrets of genetic and species adaptive evolution. 
 
Methods: This study utilized high-throughput sequencing technology and bioinformatics analysis to investigate the mitochondrial genome of the albino Eothenomys eleusis Thomas 1911. The aim was to reveal its structural or compositional characteristics, phylogenetic locationand evolutionary rate. 
 
Result: The characteristic results indicated that the genome sequence (16,347 bp) contained 37 genes and a control region, with a few genes in the &ldquo;-&rdquo; chain and most genes in the &ldquo;+&rdquo; chain. The base composition and skewness of the whole genome exhibited a significant AT preference. Except for nad1 started with GTG and nad1, cox3 and nad4 ended with T (AA), most of the 13 PCGs followed standard genetic code rules. The most commonly used codons were CUA, AUCand AUA, while the relatively commonly used amino acids were Leu1, Ile and Thr. Numerous U-G mismatches were observed in the secondary structure of tRNAs. Phylogenetic analysis confirmed that albino E. eleusis was closely related to normal E. eleusisand Eothenomys was a monophyletic group. Evolutionary rate analysis suggested that atp8 and nd4l had higher dN/dS mean values, while cox1 and cox2 were the opposite. In conclusion, this study not only revealed for the first time the mitochondrial genome characteristics and phylogenetic relationships of albino E. eleusis, but also provided a new scientific basis and reference direction for the genetic characteristics, diversity and adaptive evolution of Eothenomys and other albino species.

A Rare Mitochondrial Genome of Albino Eothenomys eleusis Thomas 1911 (Cricetidae: Arvicolinae) from Southeastern Yunnan, China and its phylogenetic Analysis