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International Journal of Evolutionary Biology
Volume 2009 (2009), Article ID 759159, 7 pages
Research Article

Heritability of Directional Asymmetry in Drosophila melanogaster

1Department of Biological Science, Florida State University, Tallahassee, FL 32306-1100, USA
2Department of Biological Sciences, California State University Long Beach, CA 90840, USA
3Department of Psychology, Arizona State University, Tempe, AZ 85287-1104, USA

Received 24 April 2009; Accepted 30 July 2009

Academic Editor: Amitabh Joshi

Copyright © 2009 Ashley J. R. Carter et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Directional asymmetry (DA), the consistent difference between a pair of morphological structures in which the same side is always larger than the other, presents an evolutionary mystery. Although many paired traits show DA, genetic variation for DA has not been unambiguously demonstrated. Artificial selection is a powerful technique for uncovering selectable genetic variation; we review and critique the limited number of previous studies that have been performed to select on DA and present the results of a novel artificial selection experiment on the DA of posterior crossvein location in Drosophila wings. Fifteen generations of selection in two genetically distinct lines were performed and none of the lines showed a significant response to selection. Our results therefore support and reconfirm previous findings; despite apparent natural variation and evolution of DA in nature, DA remains a paradoxical trait that does not respond to artificial selection.