AUTHOR=Chen Wen-Ting , Li Min , Hu Shi-Yun , Wang Su-Hao , Yuan Ming-Long 

TITLE=Comparative mitogenomic and evolutionary analysis of Lycaenidae (Insecta: Lepidoptera): Potential association with high-altitude adaptation

JOURNAL=Frontiers in Genetics

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2023.1137588

DOI=10.3389/fgene.2023.1137588

ISSN=1664-8021

ABSTRACT=<p>Harsh environments (e.g., hypoxia and cold temperatures) of the Qinghai–Tibetan Plateau have a substantial influence on adaptive evolution in various species. Some species in Lycaenidae, a large and widely distributed family of butterflies, are adapted to the Qinghai–Tibetan Plateau. Here, we sequenced four mitogenomes of two lycaenid species in the Qinghai–Tibetan Plateau and performed a detailed comparative mitogenomic analysis including nine other lycaenid mitogenomes (nine species) to explore the molecular basis of high-altitude adaptation. Based on mitogenomic data, Bayesian inference, and maximum likelihood methods, we recovered a lycaenid phylogeny of [Curetinae + (Aphnaeinae + (Lycaeninae + (Theclinae + Polyommatinae)))]. The gene content, gene arrangement, base composition, codon usage, and transfer RNA genes (sequence and structure) were highly conserved within Lycaenidae. <italic>TrnS1</italic> not only lacked the dihydrouridine arm but also showed anticodon and copy number diversity. The ratios of non-synonymous substitutions to synonymous substitutions of 13 protein-coding genes (PCGs) were less than 1.0, indicating that all PCGs evolved under purifying selection. However, signals of positive selection were detected in <italic>cox1</italic> in the two Qinghai–Tibetan Plateau lycaenid species, indicating that this gene may be associated with high-altitude adaptation. Three large non-coding regions, i.e., <italic>rrnS</italic>-<italic>trnM</italic> (control region), <italic>trnQ-nad2</italic>, and <italic>trnS2-nad1</italic>, were found in the mitogenomes of all lycaenid species. Conserved motifs in three non-coding regions (<italic>trnE-trnF</italic>, <italic>trnS1-trnE</italic>, and <italic>trnP-nad6</italic>) and long sequences in two non-coding regions (<italic>nad6-cob</italic> and <italic>cob-trnS2</italic>) were detected in the Qinghai-Tibetan Plateau lycaenid species, suggesting that these non-coding regions were involved in high-altitude adaptation. In addition to the characterization of Lycaenidae mitogenomes, this study highlights the importance of both PCGs and non-coding regions in high-altitude adaptation.</p>