Complete mitogenome of the critically endangered Asian king vulture (Sarcogypscalvus) (Aves, Accipitriformes, Accipitridae): evolutionary insights and comparative analysis.

The Asian king vulture (Sarcogypscalvus), also known as the red-headed vulture, is an Old World vulture (Gypini) facing severe population declines. This study aimed to assemble the complete mitogenome of S.calvus, explore its phylogenetic relationships, estimate divergence times, and examine genetic distances and amino acid substitutions. The mitogenome was de novo assembled from genomic DNA extracted from the blood of a female S.calvus. Phylogenetic and pairwise genetic distance analyses were conducted, comparing S.calvus with other members of Gypini, New World vultures (Cathartidae) and various other birds. The assembled mitogenome was 17,750 base pairs in length, comprising 13 protein-coding genes (PCGs), 22 transfer RNA genes, two ribosomal RNA genes and two control regions. Most PCGs used the ATG start codon, except for cytochrome c oxidase subunit 1 (COX1), which employed GTG. Phylogenetic analysis revealed a close genetic relationship between S.calvus and other members of Gypini, with an estimated divergence time of 16.7 million years ago. Genetic distance analysis indicated that S.calvus was more closely related to other Gypini, as well as to Spilornischeela and Circaetuspectoralis (Circaetini)), than to Cathartidae. Conserved amino acid substitutions between Gypini and Cathartidae were primarily observed in the NADH-ubiquinone oxidoreductase chain 1 (ND1) gene. This study provided the first complete mitogenome of S.calvus, offering new insights into its genomic structure, evolutionary history, and genetic relationships.