Fluctuating asymmetry, mating success, body size and heterozygosity in Coenagrion scitulum (Rambur) (Odonata : Coenagrionidae)

For decades fluctuating asymmetry (FA) has been considered a good descripto r of developmental stability. Correlations have been shown between FA and s everal fitness components, including mating success and heterozygosity leve l. However, some doubts have been expressed about the generalization of the se results, perhaps because of bias towards positive results and a poor cri tical approach in the first phase of FA studies. Studies on Odonata are sca rce and are concentrated on the Coenagrionidae family, with contrasting res ults in the relationships between FA and mating success, size and other fit ness components. We investigated the relationships between FA expressed as right - left wing length (R - L), body size expressed as (R+L)/2, multilocu s and single locus heterozygosity assessed by allozyme electrophoresis and short-term mating success (SMS) assessed from the status (mated or not) of the males at the moment of collection. We collected 260 males from a breedi ng population. The data were analysed by both univariate and multifactorial statistical methods. After excluding a correlation between FA and body siz e, we checked the presence of a true FA by using tests for normality, direc tional asymmetry, antisymmetry and difference from the interindividual vari ations. The results showed no correlation between FA (either signed or abso lute) and heterozygosity, body size and SMS, while heterozygosity was clear ly positively correlated with body size and with SMS. Our data suggest an e ffect of the presence of some particular alleles on SMS, instead of an effe ct of the multilocus heterozygosity, even if the presence of only three pol ymorphic loci weakens the conclusions. Finally, no correlation was found be tween body size and SMS. (C) 2001 The Association for the Study of Animal B ehaviour.