The mitochondrial genome of red-necked phalarope Phalaropus lobatus (Charadriiformes: Scolopacidae) and phylogeny analysis among Scolopacidae.

The red-necked phalarope is a wonderful species with specific morphological characters and lifestyles. Mitochondrial genomes, encoding necessary proteins involved in the system of energy metabolism, are important for the evolution and adaption of species. In this study, we determined the complete mitogenome sequence of Phalaropus lobatus (Charadriiformes: Scolopacidae). The circular genome is 16714 bp in size, containing 13 PCGs, two ribosomal RNAs and 22 tRNAs and a high AT-rich control region. The AT skew and GC skew of major strand is positive and negative respectively. Most of PCGs are biased towards A-rich except ND1. A codon usage analysis shows that 3 start codons (ATG, GTG and ATA), 4 stop codons (TAA, TAG, AGG, AGA) and two incomplete terminate codons (T-). Twenty two transfer RNAs have the typical cloverleaf structure, and a total of ten base pairs are mismatched throughout the nine tRNA genes. The phylogenetic tree based on 13 PCGs and 2 rRNA genes indicates that monophyly of the family and genus Phalaropus is close to genus Xenus plus Tringa. The analysis of selective pressure shows 13 protein-coding genes are evolving under the purifying selection and P. lobatus is different from other Scolopacidae species on the selective pressure of gene ND4. This study helps us know the inherent mechanism of mitochondrial structure and natural selection.