Interspecific and Intraspecific Genetic Diversity of Thunnus Species

Abstract

The genus Thunnus contains eight valid species with a fossil record extending back to the Middle Eocene, about 40 million years ago (Carrol, 1988, Benton, 1993). T. obesus shares approximately the same number of characters with each group; however, it is classified as a member of the subgenus Thunnus since the character states consist of adaptations to life in colder environments (Collette, 1978). In the present study, we collected complete Cyt b sequences from all eight Thunnus species, described interspecies genetic variations of the Cyt b gene, and explored their phylogeny. Results indicated that Cyt b is a good tool for tuna identification. The Thunnus phylogeny did not conform to the two-subgenera classification pattern. Another aim of this research was to investigate whether genetic differentiation appears between T. orientalis samples from Taiwan and New Zealand waters. Results suggested that these two samples shared high genetic homogeneity.