Spatio-temporal dynamics of field cricket calling behaviour: implications for female mate search and mate choice

Amount of calling activity (calling effort) is a strong determinant of male mating success in species such as orthopterans and anurans that use acoustic communication in the context of mating behaviour. While many studies in crickets have investigated the determinants of calling effort, patterns of variability in male calling effort in natural choruses remain largely unexplored. Within-individual variability in calling activity across multiple nights of calling can influence female mate search and mate choice strategies. Moreover, calling site fidelity across multiple nights of calling can also affect the female mate sampling strategy. We therefore investigated the spatio-temporal dynamics of acoustic signaling behaviour in a wild population of the field cricket species Plebeiogryllus guttiventris. We first studied the consistency of calling activity by quantifying variation in male calling effort across multiple nights of calling using repeatability analysis. Callers were inconsistent in their calling effort across nights and did not optimize nightly calling effort to increase their total number of nights spent calling. We also estimated calling site fidelity of males across multiple nights by quantifying movement of callers. Callers frequently changed their calling sites across calling nights with substantial displacement but without any significant directionality. Finally, we investigated trade-offs between within-night calling effort and energetically expensive calling song features such as call intensity and chirp rate. Calling effort was not correlated with any of the calling song features, suggesting that energetically expensive song features do not constrain male calling effort. The two key features of signaling behaviour, calling effort and call intensity, which determine the duration and spatial coverage of the sexual signal, are therefore uncorrelated and function independently.

鸣唱活动总量（鸣唱投入，calling effort）是直翅目昆虫与无尾两栖类等在交配行为中依赖声学通讯的物种雄性交配成功率的关键决定因素。尽管已有诸多针对蟋蟀的研究探讨了鸣唱投入的决定因素，但自然鸣唱集群中雄性鸣唱投入的变异模式仍未得到充分探索。雄性个体在多个夜间鸣唱活动中的个体内变异，会影响雌性的配偶搜寻与配偶选择策略。此外，雄性在多个夜间鸣唱时的鸣唱位点忠实性（calling site fidelity），同样会影响雌性的配偶取样策略。为此，我们针对田野蟋蟀物种*Plebeiogryllus guttiventris*的野生种群，探究了其声学信号行为的时空动态。我们首先通过重复性分析，量化雄性在多个夜间的鸣唱投入变异，以此研究鸣唱活动的一致性。雄性鸣虫在不同夜间的鸣唱投入并不一致，且并未通过优化单夜间的鸣唱投入来增加自身的总鸣唱夜数。我们还通过量化鸣虫的移动位移，评估了雄性在多个夜间的鸣唱位点忠实性。鸣虫在不同鸣唱夜间常会更换鸣唱位点，移动幅度较大，但未表现出显著的方向性偏好。最后，我们探究了单夜间鸣唱投入与高能量消耗的鸣唱歌曲特征（如鸣唱强度与脉冲速率）之间的权衡关系。研究发现，鸣唱投入与所有鸣唱歌曲特征均无相关性，这表明高能量消耗的鸣唱特征并不会限制雄性的鸣唱投入。因此，决定性信号时长与空间覆盖范围的两大信号行为核心特征——鸣唱投入与鸣唱强度——彼此互不相关，且功能独立。