Mitochondrial phylogeny reveals the artificial introduction of the pale chub Zacco platypus (Cyprinidae) in Taiwan

The presence of the pale chub Zacco platypus (Japanese name, Oikawa) in Taiwan has been suggested to be a result of its inadvertent introduction from Lake Biwa in Japan in the 1980s in conjunction with the Japanese Ayu, Plecoglossus altivelis altivelis, which was released several times into the Tamsui River to restock the extinct Ayu population of Taiwan. However, it is also possible that Z. platypus is native to Taiwan and has not been previously described for reasons of its narrow range. Knowledge of the colonizing history of Z. platypus is of considerable importance because it provides insight into the evolutionary process and, hence, impacts management decisions regarding this species in Taiwan. A portion of the mitochondrial D-loop was sequenced for 77 specimens from five populations of Z. platypus from Japan and Taiwan. A total of 22 haplotypes were identified, and nucleotide divergence among haplotypes ranged from 0.20% to 2.82%. Haplotype diversity was high in all populations examined, with a range from 0.718 in the Tagiri River population to 0.909 in the Lake Biwa population. Phylogenetic and statistical parsimony analyses of the molecular data revealed a close genetic relationship between Taiwanese and Japanese Z. platypus and supported the previous report that the Taiwanese Z. platypus originated in Lake Biwa in Japan.