The influence of differential survival on the distribution of fluctuating asymmetry—a modelling approach

Fluctuating asymmetry (FA) is frequently used as a potential marker of developmental stress. It is usually assumed that the distribution of FA within a population is statistically normal with a mean of zero. The relationships between three different FA-dependent survival functions and the resultant FA distribution of surviving individuals are explored. It is shown that with any biologically plausible relationship between survival and FA the resultant distribution is not normal and that this non-normality is dependent upon the form of the survival–FA relationship. Two survival probability functions resulted in leptokurtic distributions, whereas a third generated a slight decline in kurtosis values.