The superorder Cetartiodactyla has expanded to occupy a wide range of terrestrial and marine niches with very different energy requirements. As mitochondria are the primary site of energy production, we hypothesized that the structure and evolutionary rate of Cetartiodactyla mitochondrial DNA (mtDNA) have been influenced by the metabolic requirements of different ecological niches. In this study, we constructed full-length mtDNA sequences for four Cetartiodactyla species: Babyrousa babyrussa, Stenella clymene, Stenella frontalis, and Cephalorhynchus commersonii. We performed comparative mitochondrial genome analysis, selection pressure analyses, and phylogenetic independent contrasts (PIC) analysis to detect the structure and evolutionary rate of mitogenomes from Cetartiodactyla native to plain, plateau, and marine niches. We found that the structure of Cetartiodactyla mtDNA was consistent across three niches. However, selection pressure analyses showed that the evolutionary rate of mtDNA protein-coding genes (PCGs) was significantly different between niches. The marine Cetartiodactyla had the highest rate of PCG evolution, while in terrestrial species, the evolutionary rate of all PCGs except ND3 and ND6 was faster in plateau Cetartiodactyla than in plain Cetartiodactyla. PIC analysis also demonstrated that PCG evolutionary rates were positively correlated with niche type (R² = 0.1226, p = 0.04239). This study suggests divergent mechanisms for the evolution of mtDNA PCGs, prompting the adaptation of Cetartiodactyla to diverse niches.

Cetartiodactyla 超目已经扩大到占据广泛的陆地和海洋生态位，具有非常不同的能量需求。由于线粒体是能量产生的主要场所，我们假设鲸鱼线粒体 DNA (mtDNA) 的结构和进化速率受到不同生态位的代谢需求的影响。在这项研究中，我们构建了四种鲸目动物的全长 mtDNA 序列：Babyrousa babyrussa、Stenella clymene、Stenella frontalis和Cephalorhynchus commersonii。我们进行了比较线粒体基因组分析、选择压力分析和系统发育独立对比 (PIC) 分析，以检测来自原产于平原、高原和海洋生态位的鲸目动物的有丝分裂基因组的结构和进化速率。我们发现 Cetartiodactyla mtDNA 的结构在三个生态位中是一致的。然而，选择压力分析表明，mtDNA 蛋白质编码基因 (PCG) 的进化速率在生态位之间存在显着差异。海洋鲸目动物的 PCG 进化速率最高，而在陆生物种中，除ND3和ND6之外的所有 PCG 的进化速率高原鲸目动物比普通鲸目动物更快。PIC 分析还表明，PCG 进化率与生态位类型呈正相关（R ²  = 0.1226，p  = 0.04239）。这项研究提出了 mtDNA PCG 进化的不同机制，促使鲸豚适应不同的生态位。