Complete mitochondrial genomes of two relatively closed species from Gymnocypris (Cypriniformes: Cyprinidae): genome characterization and phylogenetic considerations.

The complete mitochondrial genome for Gymnocypris eckloni and Gymnocypris przewalskii ganzihonensis is 16,686 and 16,682 bp in size, respectively. Both of the mitochondrial genomes have identical genomic organization and structure including 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes and 1 control region as found in other vertebrates, with the exception of 86 bp non-coding nucleotides between tRNA(Thr) and tRNA(Pro). The phylogenetic analyses based on the concatenated nucleotide sequence of 12 PCGs on the heavy strand supported a relatively closed relationship among G. eckloni, G. p. przewalskii and G. p. ganzihonensis. The sequence divergence between G. eckloni and G. przewalskii, as well as within G. przewalskii, is relatively low compared to the average sequence divergence among other cyprinid fishes, suggesting that they are the most closely related species resulted from a relatively recent speciation event. The estimated molecular divergence time is coincided with a relatively recent speciation event occurring during the separation of the Yellow River and Qinghai Lake.