• developmental instability;
  • evolvability;
  • fluctuating asymmetry;
  • heritability;
  • organism-wide asymmetry;
  • review

Whether or not developmental instability (DI) has evolutionary potential is subject to much debate. Generally, studies fail to detect significant heritability for fluctuating asymmetry (FA), a trait assumed to reflect DI. In addition, between-trait correlations in FA are low, suggesting that DI is trait- rather than individual-specific. Among the various attempts to explain these patterns, the overall weak correlation between FA and DI at the individual level has received most attention. Presently, the concept of hypothetical repeatability (R) of individual FA allows us to correct for this weak relationship, transforming patterns of FA into unbiased patterns of DI. By applying R to data presented in the literature, we show that heritability of DI remains lower than predicted but between-trait correlations in DI substantially increase after transformation. We further provide evidence that DI changes from a trait- to an individual-specific property with higher values of R. As increasing hypothetical repeatability might co-occur with increased environmental or genetic stress, we discuss the potential implications of our results for the study of evolution of stress resistance. From this we conclude that there is an urgent need for studies that compare the evolutionary potential of developmental instability under a variety of stress conditions.