Dynamics of correlated genetic systems III. Behaviour of chromosomal segments under lethal selection

The effect of lethal selection on linked marker loci was investigated in experimental populations of Drosophila melanogaster. Replicate experimental populations were initiated using flies heterozygous for the lethal gene Stubble and with the enzyme loci esterase-C and phosphoglucomutase in linkage disequilibrium with Stubble. The dynamical behavior of the lethal and marker genes was followed through generation 41 when the experimental was terminated. The major findings of the experiment are: (1) the lethal gene was eliminated from all replicate populations; (2) the marker gene frequency behavior could not be accounted for by lethal selection and recombination alone; and (3) linkage disequilibrium among the marker genes stabilized at high levels. The results of this experiment are contrasted with those of a previous experiment, of similar design, involving the lethal gene Glued. New data from generations 40 and 41 of the Glued experiment are also presented. The qualitative agreement among experiments are also presented. The both experiments indicate the existence of other strongly selected factors in the region spanned by the marker genes.This research was supported in part by National Science Foundation grants GB41116 and DEB76-82479.