Mitochondrial genome of the Indian spot-billed duck and its phylogenetic and conservation implications

The Indian spot-billed duck, Anas poecilorhyncha is a large dabbling and non-migratory breeding bird. The identification and phylogenetic relationship of A. poecilorhyncha remain uncertain due to the presence of overlapping meristic characters and hybridization with closely related species. Molecular data aids when there are challenges in morphological identification. However, genetic characterization of A. poecilorhyncha has been paid less attention. Apart from their functional and physiological role, mitochondrial genome can also be used for various purposes, including species identification, phylogenetic analysis, understanding the domestication history of species etc. Therefore, the present study aimed to sequence the mitochondrial genome of A. poecilorhyncha and its closely related domestic species A. platyrhynchos (mallard duck) to understand their mitochondrial genome structure and phylogenetic relationships. The length of mitochondrial genome of A. poecilorhyncha and A. platyrhynchos was 16,608 and 16,604 bp respectively. Mitochondrial genome contained 37 genes and a non-coding control region. Overall, the characteristics of mitochondrial genome of both species were found to be conserved. The phylogenetic tree exhibited seven major clades (A to G) with a high bootstrap support. Notably, the Indian A. poecilorhyncha population formed a distinct clade (C) whereas the A. poecilorhyncha that were probably sampled from China grouped along with A. zonorhyncha (clade B). Besides, one of the A. poecilorhyncha probably sampled from China was placed in the clade A, which predominantly consisted of A. platyrhynchos. It suggests that Indian A. poecilorhyncha population is genetically different from Chinese A. poecilorhyncha population. Further, it sheds light on the importance of conducting a comprehensive phylogenetic study on these species. The newly sequenced mitochondrial genome of A. poecilorhyncha and A. platyrhynchos would be useful not only to have a better understanding of the phylogeny and evolution of Anas species but also to help in the conservation of A. poecilorhyncha which is under constant threat from rapid urbanization, interspecific hybridization and other human activities.