Genetic analysis of geotactic and phototactic behavior in selected strains ofDrosophila pseudoobscura

The phototactic scores of F1 and F2 progeny resulting from reciprocal matings between flies from positive and negativePhototactic strains are compatible with the hypothesis that the responsible genes are largely located in the autosomes and suggest that the bulk of the genes for positive geotactic behavior occur in a region of the X chromosome not readily separated by crossing over.

Abstract

Hybridization studies were carried out with strains ofDrosophila pseudoobscura that differ in regard to phototactic and geotactic behavior. These strains were being maintained at The Rockefeller University, New York, N. Y. Behavior was measured by using Hirsch-Hadler classification mazes. The phototactic scores of F1 and F2 progeny resulting from reciprocal matings between flies from positive and negative phototactic strains are compatible with the hypothesis that the responsible genes are largely located in the autosomes. Geotactic scores of F1, F2, F3, and backcross progeny from reciprocal matings between flies from a positive geotactic strain and a slightly negative geotactic strain suggest that the bulk of the genes for positive geotactic behavior occur in a region of the X chromosome not readily separated by crossing over. Homozygosity or hemizygosity for this region tends to give positive geotactic behavior.