Inheritance of RAPD markers and detection of interspecific hybridization with brown trout and Atlantic salmon

Genetic variation and inheritance of random amplified polymorphic DNA (RAPD) markers were studied in 20 intra- and interspecific crosses between nonanadromous salmon (Salmo salar) and brown trout (S. trutta). Altogether 21 parent fish and 166 F-1 individuals were studied. Three of the 40 primers tested produced screenable and reproducible DNA markers which separated nonanadromous salmon and brown trout. The inheritance of RAPD markers was strictly Mendelian and dominant in all types of crosses. Nonparental bands were not generated from DNAs of F-1 individuals and it is suggested that the frequency of nonparental bands should be less than 0.03% of all bands. The amount of genetic variation was generally low since nonanadromous salmon were totally monomorphic and in brown trout three primers produced six polymorphic DNA fragments. Mean similarity ((s) over bar) among 11 unrelated specimens of brown trout was 0.941 and between species (s) over bar was 0.338. Among parents, 11 out of 27 and 14 out of 24 DNA fragments were unique for nonanadromous salmon and brown trout, respectively. It is concluded that the RAPD method is one of the most time-saving and the least expensive noninvasive method for detection of interspecific hybridization. (C) 1997 Elsevier Science B.V.