The Chromosome Constitutions of a Hybrid Salmonid and Its Parental Types: Salmo Gairdneri and Salmo Clarki

摘要

A study was undertaken to investigate the application of tissue culture and histochemical banding techniques normally used in mammalian studies to fish cells and to examine the mechanisms of chromosome evolution and speciation in salmonids by comparing the chromosomes of the hybrid to those of the parental types. The application of banding techniques was generally unsuccessful in revealing bands, though quinacrine staining did reveal the presence of two fluorescent spots in the vicinity of the centromere. These were thought to be heterochromatic blocks, possibly related to the high incidence of centric fusion or fission in salmonids. Results of chromosome analysis showerd a higher incidence of acrocentric chromosomes in the hybrid than in either parental type which together with evidence for tetraploidization in salmonids is consistant with some of the requirements for species diversification. Conditions of divergence in chromosome evolution and changes which would have to occur in the hybrid for divergence from the parental types to take place are discussed. The results of a preliminary electrophoretic examination of LDH and esterase activity tended to confirm hybridization.