Senders & Their Sensory Environments: Acoustic Lessons From a Radiation of Ancient Grasshoppers

个体之间的交流最终取决于感觉器官（如眼睛或耳朵）的功能，并受到多种因素的影响，从微栖息地信号传递的物理特性到外周受体器官的神经特性。尽管人们已经对配偶选择的情况进行了彻底的研究，但环境和感觉系统之间的进化联系实际上仍未被探索。值得注意的例外发生在相当先进的脊椎动物群体中，比如青蛙和鱼。然而，脊椎动物的中枢神经系统几乎肯定比周围神经系统更具可塑性，在这一水平上感觉特征的变化很难评估。相反，无脊椎动物的感觉变化更多地集中在外围，因此无脊椎动物可以提供有用的模型系统。膀胱蚱蜢（直翅目，肺蝗科）是高度专业化的长距离（~2公里）声音信号，目前占据了一系列对比的感觉生态环境。在这个小家庭中，每个个体都有12只两种不同类型的耳朵，这为研究感觉生物学在进化过程中的作用提供了一个独特的机会。环境约束和耳朵结构功能对这一古老群体的贡献将被探讨。为了确定栖息地是否是对不同鸣叫的重要选择压力，我们将进行一系列的声音回放实验，比较森林、草原和沙漠栖息地的声音传输效率。鼓室耳和胸膜耳的详细形态结构将在不同物种之间进行比较，微扫描激光振动测量将产生耳朵调谐和灵敏度的相对估计。这将表明耳朵在多大程度上与物种特定叫声的频谱相匹配，以及不同栖息地之间感觉划分的潜力。最后，利用线粒体16S rRNA基因的DNA测序重建肺炎家族的进化史，为综合比较分析提供基础设施。该项目涉及国际旅行，将与几名本科生、研究生和博士后合作进行。这项研究的结果将为了解环境和感觉系统之间存在的复杂联系以及这些相互作用在物种形成过程中的潜在作用提供见解。此外，这些独特的无脊椎动物耳朵的进化特征可能与设计小而高灵敏度的听力设备有关。

Communication between individuals is ultimately dependent on the functioning of sensory organs, such as eyes or ears, and is affected by a variety of factors, ranging from the physics of signal transmission in the microhabitat, to the neural characteristics of peripheral receptor organs. Although mate choice scenarios have been thoroughly investigated, the evolutionary links between the environment and sensory systems remain virtually unexplored. Notable exceptions occur in fairly advanced vertebrate groups such as frogs and fish. However, the vertebrate central nervous system is almost certainly more plastic than is the peripheral nervous system, and changes in sensory characteristics at this level are difficult to evaluate. In contrast, sensory change in invertebrates is considerably more concentrated at the periphery, thus invertebrates may provide useful model systems. Bladder grasshoppers (Orthoptera, Pneumoridae) are highly specialized for long distance (~2 km) acoustic signaling and presently occupy a range of contrasting sensory-ecological environments. This small family, in which each individual has a dozen ears of two distinct types, offers a unique opportunity to investigate the role of sensory biology in evolutionary processes. The contributions of environmental constraints and ear structure and function will be explored in this ancient group. To determine whether habitat is a significant selection pressure for divergent calling songs, a series of acoustic playback experiments will be performed to compare the efficiency of sound transmission in forest, grassland and desert habitats. The detailed morphological structure of both a tympanate- and pleural ears will be compared across species, and microscanning laser vibrometry will yield relative estimates of ear tuning and sensitivity. These will indicate to what extent ears are matched to the frequency spectra of species-specific calls, and the potential for sensory partitioning across different habitats. Finally, the evolutionary history of the pneumorid family will be reconstructed using DNA sequencing of the mitochondrial 16S rRNA gene to provide the infrastructure for integrated comparative analyses. This project involves international travel, and will be carried out in collaboration with several undergraduate, graduate, and post-doctoral associates. The results of this study will provide insight into the complex associations that exist between the environment and sensory systems, and the potential role of these interactions in the speciation process. Moreover, evolved features of these unique invertebrate ears may be relevant in the design of small, highly sensitive hearing devices.