Unexpected male choosiness: condition-dependent mating strategies of crayfish

Abstract

Few studies have looked at variation in male mating strategies in relation to phenotypic quality perhaps because males are not traditionally thought to be choosy. Recent theoretical models, however, predict that body condition should affect mating preferences. In crayfish, chelae are important weapons and may be reliable indicators of quality in both sexes. Here, we investigated mating preference in male red swamp crayfish, Procambarus clarkii , of standardized size and different chelae condition. In the first experiment, the quality of each crayfish was classified according to whether both chelae were intact or lost. We compared the mating preferences of high-quality males (two chelae) and low-quality males (no chelae) when choosing high- and low-quality females. The second experiment explored whether males with a single chela chose females based on their single chela side (left-clawed and right-clawed). The results showed that high-quality males were not choosy, while low-quality males preferred high-quality females. Left-clawed males preferred right-clawed females, but right-clawed males did not discriminate between partners based on chela side. We consider this may be due to an adaptation in mating strategies and handedness. Our study suggests a conditional male mating strategy based on quality and symmetry which could maintain the success of copulation regardless of chelae loss. • Males of red swamp crayfish adjust mating strategy depending on chelae condition. • High-quality males are unselective. • Low-quality males show preference for high-quality females. • Males with single left and right chela both prefer mirror-symmetry females.