Characterization and Phylogenetic Analysis of the Complete Mitochondrial Genome of .

is a large diving duck belonging to the family Anatidae. However, the phylogenetic relationship among these species remains unclear due to the presence of extensive interspecific hybridization events within the genus. Here, we sequenced and annotated the complete mitochondrial genome of , which contained 22 tRNAs, 13 protein-coding genes (PCGs), 2 ribosomal RNAs, and 1 D-loop, with a length of 16,617 bp. The sizes of the PCGs ranged from 297 to 1824 bp and were all, except for , located on the heavy chain (H). ATG and TAA were the most common start and termination codons of the 13 PCGs, respectively. The fastest- and slowest-evolving genes were and , respectively. Codon usage analysis indicated that CUA, AUC, GCC, UUC, CUC, and ACC were the six most frequent codons. The nucleotide diversity values indicated a high level of genetic diversity in . analysis suggested a widespread gene exchange between and . Moreover, phylogenetic reconstructions using the mitochondrial genomes of all available Anatidae species showed that, in addition to , four major clades among the Anatidae (Dendrocygninae, Oxyurinae, Anserinae, and Anatinae) were closely related to . Overall, this study provides valuable information on the evolution of and new insights into the phylogeny of Anatidae.