GENE DUPLICATION WITHIN THE FAMILY SALMONIDAE: DISOMIC INHERITANCE OF TWO LOCI REPORTED TO BE TETRASOMIC IN RAINBOW TROUT

Frederick W. Allendorf 1 and Fred M. Utter 2

1 College of Fisheries, University of Washington, Seattle, Washington 98195
2 Northwest Fisheries Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Boulevard East Seattle, Washington 98112

We describe our studies of the genetics of allelic variation for NADP-dependent isocitrate dehydrogenase (IDH) in rainbow trout (Salmo gairdneri). Five populations of rainbow trout were studied to determine the phenotypic distribution of IDH; 453 progeny from a number of controlled matings were examined to determine the nature of inheritance of these alleles. The variation was found to be the result of four alleles producing protein subunits of differing electrophoretic mobilities. Progeny from crosses clearly demonstrated the presence of two disomic loci controlling the variation, rather than one tetrasomic locus as had been previously reported. These findings support our contention that the hypothesis of a tetraploid event in salmonid evolution should not be uncritically accepted.

Submitted on February 22, 1973