Justus-Liebig-Universität Gießen, Institute for Animal Physiology, AG Integrative Sensory Physiology, Gießen, Germany.
Georg-August University Göttingen, Cellular Neurobiology, Schwann-Schleiden-Forschungszentrum, Göttingen, Germany.
PLoS One. 2014 Jan 28;9(1):e87211. doi: 10.1371/journal.pone.0087211. eCollection 2014.
Sensory modalities typically are important for both sexes, although sex-specific functional adaptations may occur frequently. This is true for hearing as well. Consequently, distinct behavioural functions were identified for the different insect hearing systems. Here we describe a first case, where a trait of an evolutionary novelty and a highly specialized hearing organ is adaptive in only one sex. The main function of hearing of the parasitoid fly Emblemasoma auditrix is to locate the host, males of the cicada species Okanagana rimosa, by their calling song. This task is performed by female flies, which deposit larvae into the host. We show that male E. auditrix possess a hearing sense as well. The morphology of the tympanal organ of male E. auditrix is rather similar to the female ear, which is 8% broader than the male ear. In both sexes the physiological hearing threshold is tuned to 5 kHz. Behavioural tests show that males are able to orient towards the host calling song, although phonotaxis often is incomplete. However, despite extensive observations in the field and substantial knowledge of the biology of E. auditrix, no potentially adaptive function of the male auditory sense has been identified. This unique hearing system might represent an intralocus sexual conflict, as the complex sense organ and the behavioural relevant neuronal network is adaptive for only one sex. The correlated evolution of the sense organ in both sexes might impose substantial constraints on the sensory properties of the ear. Similar constraints, although hidden, might also apply to other sensory systems in which behavioural functions differ between sexes.
感觉模态通常对两性都很重要，尽管性别特异性的功能适应可能经常发生。这同样适用于听觉。因此，不同昆虫听觉系统的不同行为功能被确定。在这里，我们描述了一个首例情况，其中一种进化新颖性的特征和高度专业化的听觉器官仅在一种性别中具有适应性。寄生蝇 Emblemasoma auditrix 的主要听觉功能是通过蝉种 Okanagana rimosa 的叫声来定位宿主，即雄性。这项任务是由雌性蝇完成的，它们将幼虫注入宿主中。我们表明，雄性 E. auditrix 也具有听觉。雄性 E. auditrix 的鼓膜器官形态与雌性耳朵相当相似，比雄性耳朵宽 8%。在两性中，生理听觉阈值都调谐到 5 kHz。行为测试表明，雄性能够朝向宿主的叫声定向，尽管声向性往往不完整。然而，尽管对 E. auditrix 的生物学进行了广泛的观察和深入了解，但尚未确定雄性听觉的潜在适应性功能。这种独特的听觉系统可能代表了一种种内性冲突，因为复杂的感觉器官和与行为相关的神经元网络仅对一种性别具有适应性。两性中感觉器官的相关进化可能对耳朵的感觉特性施加了实质性的限制。类似的限制，尽管隐藏起来，也可能适用于其他行为功能在两性之间存在差异的感觉系统。
