Complete mitochondrial genome of the world's most endangered tern, Thalasseus bernsteini, and a mitogenomic phylogenetic study of the Laridae family

Thalasseus bernsteini (Chinese crested tern), known as the rarest tern in the world, has become critically endangered with a severely diminished population. Understanding its genetic diversity is crucial for conservation efforts. However, no genomic resource has been publicly reported for this species. In this study, we discuss the first complete mitochondrial genome (mitogenome) of T. bernsteini assembled from an egg sample collected from a newly established breeding site on Yuksan Island, South Korea. The 16,737 bp mitogenome contains 37 genes, including 13 protein-coding genes, 22 tRNAs, and two rRNAs, exhibiting a typical gene order of avian mitogenomes. Phylogenetic analyses based on mitogenomic data confirmed the phylogenetic relationships between T. bernsteini within the Laridae family and other Charadriiformes species. Additionally, the divergence timeline of the terns was estimated, highlighting the evolutionary events that shaped their lineage. Our findings provide valuable genomic resources for future conservation genetic and phylogenetic studies of this critically endangered species, aiding in efforts to protect and manage dwindling populations.