Female preference functions drive interpopulation divergence in male signalling: call diversity in the bushcricket Ephippiger diurnus

Female preferences play a major role in the elaboration and diversification of male traits: as a selective pressure on males, variation in female preferences can generate population divergence and ultimately, speciation. We studied how interpopulation differences in the shape of female mate preference functions may have shaped male advertisement signals in the bushcricket Ephippiger diurnus. This species is distributed as geographically isolated populations with striking interpopulation variation in male acoustic signals, most notably in the number of syllables per call. Here, we asked whether differences in the shape of preference functions exist among populations and whether those differences may have driven male signal evolution resulting in the observed differences in syllable numbers. Our results reveal fundamental differences in female preferences among populations, with differences in the overall preference function shape corresponding to differences in male signals. These differences in female preferences best explain the major differences in male signals among populations. The interpopulation variation in signals and preferences potentially reflects the evolutionary history of the species and may contribute to further divergence among populations and subsequent speciation.

雌性偏好对于雄性性状的塑造与多样化起着核心作用：作为施加于雄性的选择压力，雌性偏好的差异能够引发种群分化，最终导致物种形成。本研究以昼鸣棘螽（Ephippiger diurnus）为研究对象，探讨雌性配偶偏好函数形态的种群间差异如何塑造了雄性的求偶声学信号。该物种的种群在地理上相互隔离，雄性声学信号存在显著的种群间差异，其中尤以每声鸣叫的音节数差异最为突出。本研究旨在解答两个关键问题：其一，不同种群的偏好函数形态是否存在差异；其二，此类差异是否推动了雄性信号的演化，进而造就了已观测到的音节数差异。研究结果揭示了不同种群雌性偏好的根本性差异，且偏好函数整体形态的差异与雄性信号的差异高度匹配。雌性偏好的这类差异，能够最合理地解释种群间雄性信号的主要差异。信号与偏好的种群间差异，或能反映该物种的演化历史，且可能进一步推动种群间的分化，乃至后续的物种形成。