Symmetry 2010, 2, 466-540; doi:10.3390/sym2020466 OPEN ACCESS Symmetry ISSN 2073-8994 www.mdpi.com/journal/symmetry Review Fluctuating Asymmetry: Methods, Theory, and Applications John H. Graham 1,†,*, Shmuel Raz 2,3,†, Hagit Hel-Or 4 and Eviatar Nevo 3 1 Department of Biology, Berry College, Mount Berry, Georgia 30149, USA 2 Department of Evolutionary and Environmental Biology, University of Haifa, Haifa 31905, Israel; E-Mail:
[email protected] 3 Institute of Evolution, University of Haifa, Haifa 31905, Israel; E-Mail:
[email protected] 4 Department of Computer Science, University of Haifa, Haifa 31905 Israel; E-Mail:
[email protected] † These authors contributed equally to this work. * Author to whom correspondence should be addressed; E-Mail:
[email protected]; Tel.: +1-706- 290-2671; Fax: +1-706-238-7855. Received: 22 December 2009; in revised form: 27 February 2010 / Accepted: 15 March 2010 / Published: 25 March 2010 Abstract: Fluctuating asymmetry consists of random deviations from perfect symmetry in populations of organisms. It is a measure of developmental noise, which reflects a population’s average state of adaptation and coadaptation. Moreover, it increases under both environmental and genetic stress, though responses are often inconsistent. Researchers base studies of fluctuating asymmetry upon deviations from bilateral, radial, rotational, dihedral, translational, helical, and fractal symmetries. Here, we review old and new methods of measuring fluctuating asymmetry, including measures of dispersion, landmark methods for shape asymmetry, and continuous symmetry measures. We also review the theory, developmental origins, and applications of fluctuating asymmetry, and attempt to explain conflicting results.