Application of a Genetic Sex Identification Method on the Japanese Giant Salamander and its Hybrids with the Chinese Giant Salamander (Urodela: Cryptobranchidae)

A genetic sex identification method was applied to the Japanese Giant Salamander and its hybrids with the introduced Chinese Giant Salamander. This method detects female-specific sequences on the W chromosome by PCR, using specific primers originally designed for the Chinese Giant Salamander. We improved the method for application to the Japanese Giant Salamander and the hybrids. We then applied our new technique to examine the sex ratio of hybrid larvae collected from one breeding nest in the wild. The sex ratio was equal between sexes at this site, suggesting that their sex is determined by chromosomal combination.