Transferrin groups of tunas.

RANSFERRIN pol.ymorphism has been demonstrated by gel electrophoresis Tin many vertebrates. These include men (SMITHIES and HILLER 1959), monkeys (GOODMAN and POULIK 1961), cattle (ASHTON 1958; SMITHIES and HICKMAN 1958), sheep and goats (ASHTON and FERGUSON 1963; EFREMOV and BRAEND 1964), horses (BRAEND and STORMONT 1964), burros (NIECE and KRACHT 1967), pigs (ASHTON 1960a), mice (ASHTON and BRADEN 196l), antelopes (ASHTON and CARR 1965), harp seals (NAEVDAL 1965), doves (MUELLER 1961), chickens ( OGDEN, MORTON, GILMOUR and MCDERMID 1962), and gadoid fishes ( MBLLER and NAEVDAL 1966; M ~ L L E R 1966). BARRETT and TSUYUKI (1967) have found polymorphisms of transferrin in several scombroid fishes-yellowfin tuna, skipjack tuna, albacore, and bonito. The animals most thoroughly studied have been domestic cattle. Transferrin phenotypes have been shown to be associated with differences in fertility and fetal mortality (ASHTON 1959), and maternal-fetal incompatibility (ASHTON 1965). Transferrin phenotypes have also been associated with differences in the production of milk and butterfat (ASHTON 1960b; ASHTON, FALLON and SUTHERLAND 1964). This paper (1 ) describes transferrin polymorphisms in skipjack tuna (Katsuwonus pelamis), southern bluefin tuna (Thunnus naccoyi) , and yellowfin tuna ( T . albacares) from the Atlantic and Pacific Oceans; (2) presents evidence of differential adaptive vallues of phenotypes in skipjack tuna; and (3) discusses possible mechanisms of maintaining transferrin polymorphism in a randomly mating population.