Data from: Male-female interactions drive the (un)repeatability of copula duration in an insect.

Across the animal kingdom the duration of copulation varies enormously from a few seconds to several days. Functional explanations for this variation are largely embedded within sperm competition theory in which males modulate the duration of copula in order to optimise their fitness. However, copulation is the union of two protagonists which are likely to have separate and often conflicting reproductive interests, yet few experimental designs specifically assess the effect of male-female interactions on the duration of copulation. This can result in inexact assertions over which sex controls copulatory behaviour. Here we analyse the repeatability of copulatory behaviour in the seed beetle Callosobruchus maculatus to determine which sex exerts primary influence over copulation duration. In C. maculatus, copulation follows two distinct phases: an initial quiescent phase followed by a period of vigorous female kicking behaviour that culminates in the termination of copulation. When males or females copulated with several novel mates, copulatory behaviour was not significantly repeatable. By contrast, when males or females mated repeatedly with the same mate, copula duration was repeatable. These data suggest copulatory behaviour in C. maculatus to be largely the product of male-female interactions rather than the consistent, sex-specific modulation of copula duration of one protagonist in response to the phenotypic variation presented by the other protagonist.

在动物界中，交配时长的差异极为悬殊，从数秒至数天不等。针对这一差异的功能性解释大多根植于精子竞争理论（sperm competition theory），该理论提出雄性可通过调节交配时长以优化自身的进化适合度（fitness）。然而，交配是两个个体的结合，二者的繁殖利益往往相互独立且时常存在冲突，但目前鲜有实验设计专门评估雌雄个体间的相互作用对交配时长的影响。这导致学界难以精准判断究竟哪一性别掌控交配行为。
本研究以绿豆象（Callosobruchus maculatus）为实验对象，分析其交配行为的可重复性，以明确哪一性别对交配时长起主导调控作用。
在绿豆象的交配过程中存在两个截然不同的阶段：初始的静止阶段，随后是雌性表现出剧烈的踢踹行为，最终以此终止交配。
当雄性或雌性与多个新配偶进行交配时，其交配行为未呈现出显著的可重复性。
与之相反，当雄性或雌性与同一配偶反复交配时，交配时长则表现出可重复性。
上述实验数据表明，绿豆象的交配行为在很大程度上是雌雄个体相互作用的产物，而非某一方仅根据另一方所呈现的表型变异（phenotypic variation）进行的稳定且具有性别特异性的交配时长调节。