Further Analysis of Hybrid Dysgenesis in Drosophila melanogaster

Abstract

A systematic survey of the sterility of second-generation females produced by backcrossing hybrids of dysgenically interacting strains of D. melanogaster is reported. The effects of Fl rearing temperature and chromosomal constitution on this sterility were explicable in terms of the regulation of a transposable, inserted genetic element called the P factor which is known to be associated with hybrid dysgenesis. No applied radiation or chemical treatment induced dysgenic aberrations where they would not normally be found but, where they were found, EDT A slightly increased and ultraviolet radiation reduced their intensity. The results of previous temperature-shift experiments have implicated different periods during development as having the most effect on female'fertility. The present studies show little effect of interstrain variation on this critical period. Critical periods are identified for male sterility and recombination. Transmission ratio distortion has been shown to occur only in one of the reciprocal-cross hybrids (M x P) of parental strains causing dysgenesis. The degree of distortion in such crosses is shown here to vary between M strains crossed to the same P strain. Few data are available for the second (P x M) cross. The data reported here confirm that whatever distortion occurs in this cross is slight.

Hybrid Dysgenesis in Drosophila melanogaster: Evidence from Sterility and Southern Hybridization Tests that P Cytotype Is Not Maintained in the Absence of Chromosomal P Factors

“…The first, labelled PH, is an isolate of the Harwich (United States) stock, received from M. G. KIDWELL in 1979. The second, labelled PW, derives from the stock Para Wirra (Australia) [see COLGAN and SVED (1982)] and has been held in bottle populations for about 10 yr.…”

Bar reversion and hybrid dysgenesis inDrosophila melanogaster:reversion in males and in inversions

“…Cytological examinations of revertants were made on polytene chromosomes prepared by the method of Lefevre (1976). Tests of the fertility of females followed Colgan & Sved (1982). Reversion was scored among the progeny of pure strain flies, of hybrids of two Barcarrying strains and of dysgenic and non-dysgenic backcross flies.…”