A Potential Regulatory Polymorphism Upstream of hairy Is Not Associated With Bristle Number Variation in Wild-Caught DrosophilaSequence data from this article have been deposited with the EMBL/GenBank Data Libraries under accession nos. AY587211, AY587212, AY587213, AY587214, AY587215, AY587216, AY587217, AY587218, AY587219, AY587220, AY587221, AY587222, AY587223, AY587224, AY587225, AY587226.

To extend results from laboratory genetic mapping experiments to natural populations it is necessary to estimate the phenotypic effects attributable to laboratory-identified genetic factors in nature. We retested a polymorphism found to be strongly associated with an increase of 0.35 sternopleural bristles in laboratory strains in two large samples of wild-caught Drosophila melanogaster. Despite >90% power to detect effects as low as 0.27 bristles (<1% of the total variation in bristle number) we did not replicate the association in nature. Potential explanations for this result are explored.