Evaluating the effects of cheliped morphology on the mating behavior of two invasive crayfish, the Louisiana crayfish (Procambarus clarkii) (Girard, 1852) and the Virile crayfish (Faxonius virilis) (Hagen, 1870)
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The Louisiana crayfish (Procambarus clarkii) is a large-bodied crayfish that is native to northeastern Mexico and the south-central United States, with a breeding season ranging from June to October in colder climates or June through November in warmer climates, with the inclusion of a second mating in the spring. This system combined with the r-selected characteristics of this species allows it to produce a massive amount of offspring, increasing its potential to become invasive. The Virile crayfish (Faxonius virilis) is native to the Great Lakes region of the United States, and shares similar life history traits with P. clarkii. Despite the extensive research on the invasive potential of these organisms, the visual behavioral aspects of the mating system have been mostly neglected. This study has investigated how cheliped autotomy influences female choice and copulation behavior of these two species of crayfish. Previous studies showed that P. clarkii females preferred males of larger body size or larger chelae size, but not which played a larger role. In other crayfish species, chelae asymmetry has shown no impact on mate choice, but no studies have looked at the impact of chelae loss in mate choice. Chelae loss or injury is fairly common in crayfish due to predatory and intraspecific interactions. I investigated 3 physical traits: chelae presence, function, and chelae-body size ratio in female mate choice. Females were given a choice between two different males to determine the importance of these traits in male mating success in two different experiments. Females of both species showed no preference for males based on any of the visual traits examined. Copulations were infrequent and not indicative of female preference for a particular male phenotype. Chelae function and chelae-body size ratio impacted male copulation attempts for P. clarkii. This suggests that further research must be done to include other visual, and chemical, stimuli to truly understand the crayfish mating system and the role of female choice.