Northwest Fisheries Science Center

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Document Type: Chapter or Section
Center: NWFSC
Document ID: 7723
Type of Book: Technical
Section or Chapter Title: Gene duplication within the family Salmonidae II:  Detection and determination of the genetic control of loci through inheritance studies and the examination of populations
Book Title: Isozymes IV: genetics and evolution
Author: Fred W. Allendorf, Fred M. Utter, Bernard P. May
Editor: Clement L. Markert (Ed.)
Publication Year: 1975
Publisher: Academic Press. New York
Pages: 415-432

We examine the interpretation of electrophoretic data reflecting duplicated gene loci in salmonid fishes.  Genetic models are considered to explain electrophoretic patterns of proteins reflecting duplicated genes where common alleles give rise to proteins of identical electrophoretic mobilities.  It is shown that in the absence of breeding data it is impossible to distinguish between a model of tetrasomic inheritance and one of disomic inheritance where alleles segregating at two loci occur at the same frequency.  However, it is shown that disomic inheritance can be verified by the examination of population phenotypic distribution under certain conditions.  Family data are presented verifying disomic inheritance of malate dehydrogenase in rainbow trout (Salmo gairdneri) and aspartate aminotransferase in chum salmon (Oncorhynchus keta).  Examination of 19 salmonid biochemical systems indicate that 8 systems clearly reflect gene duplication, 8 do not, and 3 systems lack variation, precluding detection of gene duplication, genetic variants at all of the duplicated loci appear to segregate disomically.  No significant evidence for genetic linkage was found among 10 jointly segregating pairs of loci in rainbow trout and one pair of loci in chum salmon; one comparison in rainbow trout (IDH-AGPDH) approached significance (P = 0.06).