Interspecific and Intraspecific Genetic Diversity of Thunnus Species
نویسندگان
چکیده
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). Collette (1978) distinguished tunas into the temperate subgenus Thunnus (bluefin tuna group) and the tropical subgenus Neothunnus (yellowfin group) by the presence or absence of a central heat exchanger. The yellowfin group contains blackfin (T. atlanticus), longtail (T. tonggol), and yellowfin (T. albacares) tunas. Albacore (T. alalunga), bigeye (T. obesus), northern bluefin (T. thynnus & T. orientalis), and southern bluefin (T. maccoyii) tunas are members of the bluefin group. 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).
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