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Genetic characterization of hybridization and introgression between anadromous rainbow trout ( Oncorhynchus mykiss irideus ) and coastal cutthroat trout ( O. clarki clarki )
Author(s) -
Young William P.,
Ostberg Carl O.,
Keim Paul,
Thorgaard Gary H.
Publication year - 2001
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1046/j.1365-294x.2001.01247.x
Subject(s) - biology , introgression , rainbow trout , backcrossing , trout , hybrid , amplified fragment length polymorphism , zoology , mitochondrial dna , oncorhynchus , salvelinus , ecology , genetics , evolutionary biology , fishery , genetic diversity , gene , botany , population , fish <actinopterygii> , demography , sociology
Interspecific hybridization represents a dynamic evolutionary phenomenon and major conservation problem in salmonid fishes. In this study we used amplified fragment length polymorphisms (AFLP) and mitochondrial DNA (mtDNA) markers to describe the extent and characterize the pattern of hybridization and introgression between coastal rainbow trout ( Oncorhynchus mykiss irideus ) and coastal cutthroat trout ( O. clarki clarki ). Hybrid individuals were initially identified using principle coordinate analysis of 133 polymorphic AFLP markers. Subsequent analysis using 23 diagnostic AFLP markers revealed the presence of F 1 , rainbow trout backcross, cutthroat trout backcross and later‐generation hybrids. mtDNA analysis demonstrated equal numbers of F 1 hybrids with rainbow and cutthroat trout mtDNA indicating reciprocal mating of the parental types. In contrast, rainbow and cutthroat trout backcross hybrids always exhibited the mtDNA from the recurrent parent, indicating a male hybrid mating with a pure female. This study illustrates the usefulness of the AFLP technique for generating large numbers of species diagnostic markers. The pattern of hybridization raises many questions concerning the existence and action of reproductive isolating mechanisms between these two species. Our findings are consistent with the hypothesis that introgression between anadromous populations of coastal rainbow and coastal cutthroat trout is limited by an environment‐dependent reduction in hybrid fitness.