Effect of the genetic background on recombination frequency in the cn-vg region of the second chromosome of natural populations of Drosophila melanogaster.

Newly established test stocks made it possible to follow the effect of three different defined genetic backgrounds (first and third chromosomes) on recombination frequency in the cn-vg region of the second chromosomes isolated from four natural populations of Drosophila melanogaster. One background was composed of the chromosomes with inversions obtained from the stock (see article) and another two backgrounds were of the standard type consisting one-half of the original chromosomes from the natural population and one-half of the chromosomes of the stocks Oregon R or Samarkand. Using the analysis of variance significant differences in RF values were found between and within populations and especially between the different backgrounds. Some simple and double interactions between the above factors played a role. The highest RF values were obtained on the background [corrected] with inversions. The effect of the different genetic backgrounds [corrected] by the action of the genetic modifiers of RF. The different genetic backgrounds affected the variations in RF values in individual populations and the different populations reacted differentially to the changed genetic background. The design of the experiment permitted an estimation of the causal compoenents of variance and heritability of RF from the sib analysis. The additive component of variance was present in only two of the populations under test; the respective estimates of heritability were very low.