Data from: Sensory evolution of hearing in tettigoniids with differing communication systems

In Tettigoniidae (Orthoptera: Ensifera), hearing organs are essential in mate detection. Male tettigoniids usually produce calling songs by tegminal stridulation, whereas females approach the males phonotactically. This unidirectional communication system is the most common one among tettigoniids. In several tettigoniid lineages, females have evolved acoustic replies to the male calling song which constitutes a bidirectional communication system. The genus Poecilimon (Tettigoniidae: Phaneropterinae) is of special interest because the ancestral state of bidirectional communication, with calling males and responding females, has been reversed repeatedly to unidirectional communication. Acoustic communication is mediated by hearing organs that are adapted to the conspecific signals. Therefore, we analyse the auditory system in the Tettigoniidae genus Poecilimon for functional adaptations in three characteristics: (i) dimension of sound-receiving structures (tympanum and acoustic spiracle), (ii) number of auditory sensilla and (iii) hearing sensitivity. Profound differences in the auditory system correlate with uni- or bidirectional communication. Among the sound-receiving structures, the tympana scale with body size, whereas the acoustic spiracle, the major sound input structure, was drastically reduced in unidirectional communicating species. In the unidirectional P. ampliatus group, auditory sensilla are severely reduced in numbers, but not in the unidirectional P. propinquus group. Within the P. ampliatus group, the number of auditory sensilla is further reduced in P. intermedius which lost acoustic signalling due to parthenogenesis. The auditory sensitivity correlated with the size of the acoustic spiracle, as hearing sensitivity was better with larger spiracles, especially in the ultrasonic range. Our results show a significant reduction in auditory structures, shaped by the differing sex roles during mate detection.在螽斯科（Tettigoniidae，直翅目Orthoptera：螽亚目Ensifera）昆虫中，听觉器官在配偶识别过程中发挥关键作用。螽斯科雄虫通常通过前翅摩擦（tegminal stridulation）发出求偶鸣曲，而雌虫则通过趋声性（phonotaxis）向雄虫靠近。这种单向通讯系统是螽斯科昆虫中最为普遍的通讯模式。在多个螽斯科支系中，雌虫演化出了针对雄虫求偶鸣曲的声学应答行为，由此形成了双向通讯系统。 鼓螽属（Poecilimon，隶属于螽斯科露螽亚科Phaneropterinae）具有特殊研究价值，因为其以雄虫鸣曲、雌虫应答为特征的双向通讯祖先状态，曾多次反转演变为单向通讯系统。 声学通讯依赖于适配同种信号的听觉器官实现。因此，本研究针对螽斯科鼓螽属（Poecilimon）的听觉系统，从3个特征维度分析其功能适应性：(i) 声音接收结构（鼓膜tympanum与声学气门acoustic spiracle）的尺寸；(ii) 听觉感器（auditory sensilla）的数量；(iii) 听觉灵敏度。 听觉系统的显著差异与单向或双向通讯模式密切相关。在声音接收结构中，鼓膜尺寸随虫体大小成比例变化，而作为主要声音输入结构的声学气门，在单向通讯物种中出现了显著缩减。在单向通讯的P. ampliatus类群中，听觉感器数量大幅减少，但在单向通讯的P. propinquus类群中并未出现这一现象。在P. ampliatus类群内部，因孤雌生殖（parthenogenesis）丧失声学信号产生能力的P. intermedius，其听觉感器数量进一步减少。 听觉灵敏度与声学气门尺寸呈正相关：气门越大，听觉灵敏度越高，尤其在超声频段表现显著。本研究结果表明，听觉结构出现了显著缩减，这一演化特征由配偶识别过程中不同的性别角色所塑造。