A Variance Partitioning Approach Identifies the Absence of Mate Choice and the Lack of Forced Copulation in the Water...

AbstractIn animals, choosers assess the attractiveness of courting individuals based on multiple sexual traits rather than a single trait. To quantify mate choice toward combinations of these traits, it is essential to analyze choosers' responses. The chooser's responses can depend on the courter's identity, indicating that the mate choice of the chooser is based on the courter's overall attractiveness. In addition, examining mate choice across different mating stages (precopulatory, copulatory, and postcopulatory) by assessing courter identity effects on chooser behaviors can further clarify mating dynamics. Moreover, estimating the contribution of each sex to the variation in copulation frequency can provide insights into the mating system. Here, we examined the water strider Gerris gracilicornis and found that pre- and postcopulatory behaviors in both sexes did not vary with the identity of the opposite sex, indicating a lack of pre- or postcopulatory mate choice in either sex. Our results also suggested that copulation frequency was not influenced by males, thereby confirming the absence of forced copulation in G. gracilicornis. Overall, this study offers a novel approach for understanding the mating system of a species and assessing stage-specific mate choice based on overall attractiveness.