Fitness components of male and female winter moths (Operophtera brumata L.) (Lepidoptera, Geometridae) relative to measures of body size and asymmetry

Abstract

In this article we present data from two experiments on the association between individual asymmetry and fitness in the winter moth. We performed a mate selection experiment and compared asymmetry and body size of mated and unmated males collected in the field. Individual asymmetry was not associated with copulation probability, adult life span, or body size, even though body size is a reliable indicator of larval and pupal survival, female fecundity, adult life span, and thus expected fitness. There was only a weak positive effect of body size on mating success, contrary to the strong effect of female size on male choice found in previous experiments. Both males and females were capable of repeated mating, and the number of matings was correlated with female size, but neither with male body size nor with adult asymmetry. Yet, females engaged in repeated matings more frequently if they were first mated to a more asymmetrical male. This may indicate that more asymmetrical males lose paternity due to female remating, although direct paternity analyses need to be carried out. In addition, repeated mating may be uncommon under field situations. In conclusion, the relationship between individual asymmetry and fitness seems to be at best weak in the winter moth