Correlated Response to Phototactic Selection

Artificial selection for positive and negative phototaxis was conducted in populations of Drosophila melanogaster that were polymorphic at the sepia locus. Photoselection response was accompanied by a correlated response in the frequency of the sepia allele. Changes in sepia frequency were shown to be significantly different from those predicted by several neutral models. Implications of this correlated response are briefly dis-cussed in terms of the neurogenetic basis of phototaxis. KEY WORDS: phototaxis; Drosophila; correlated response; selection; sepia