Fluctuating asymmetry as a bioindicator of stress: Comparing efficacy of analyses involving multiple traits

Researchers have suggested fluctuating asymmetry (FA) as an indicator of en vironmental stress and have usually tested this assertion by examining rela tions between FA of single traits and stress. Fluctuating asymmetry stress relations are real but are typically weak and difficult to detect. Research ers would like to maximize the probability of detecting FA-stress relations when they exist. We assert that analyses based on the FA of multiple trait s may provide better methods for detecting stress. In this article, we used computer simulations to compare the ability of six analyses to detect diff erences in FA between stressed and unstressed populations. We show that the optimal analysis depends upon the underlying form of the FA distributions. We also show that two Of the analyses had inflated Type I errors in some s ituations. Finally, we quantify the advantage of our preferred analysis ove r those of single-trait FA in detecting stress.