Abstract
Mitochondrial cytochrome C oxidase subunit I (COI) has been used as a DNA barcode to identify population genetic diversity and distinguish animal species as it is variable enough to distinguish between species, yet suitably conserved. A new native chicken breed, named Danzhou chicken was discovered in Hainan, China in 2014, although identification is difficult by morphological examination alone. The mitochondrial COI genes of six chicken breeds, including four local and two imported breeds (Danzhou, Wenchang, Bawang, Beijing-You, Hy-Line Brown, and Ross) were compared and assessed in terms of their efficacy for DNA barcoding. The results showed that the number of COI gene variants in Danzhou chickens was less than those of other breeds, except Bawang and the genetic structure was relatively stable. The Kimura 2-parameter genetic distance between Danzhou chickens and the five other breeds was from ∼0.001 to 0.734. The genetic distance of the six breeds was ∼0.001-0.339, with that of Danzhou being the highest (0.339). Danzhou chickens clustered with Bawang and Wenchang chickens in the phylogenetic tree due to geographic closeness. Danzhou chickens could be identified more accurately using COI barcoding. Multiple molecular markers combined with morphological differences were more persuasive for identifying species.