| origin of reproductive isolation in the absence of apparent genic differentiation in a geographic isolate of drosophila pseudoobscura. | f(1) males obtained from the cross of d. pseudoobscura females from bogotá (colombia) x males of this species from mainland, i.e. populations from various locations in the united states and from guatemala, are sterile. this sterility is due to genes located on the x chromosome and the autosomes; the y chromosome is not involved. the percentage of sterile males in backcrosses can be explained by assuming an interaction between two loci on the bogotá x chromosome and probably two loci, one each on ... | 1972 | 5073854 |