Tenors Not Sopranos: Bio-Mechanical Constraints on Calling Song Frequencies in the Mediterranean Field-Cricket
Tenors Not Sopranos: Bio-Mechanical Constraints on Calling Song Frequencies in the Mediterranean Field-Cricket
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DOI：
10.3389/fevo.2021.647786
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发表时间：
2021-04-20
影响因子：
3
通讯作者：
Robert, Daniel
中科院分区：
文献类型：
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作者：
Jonsson, Thorin;Montealegre-Z, Fernando;Robert, Daniel
雄性蟋蟀和它们的近亲灌木蟋蟀（分别是灰蟋蟀科和狐蝠科；直翅目和狐蝠目）通过发出响亮的鸣叫来吸引远处的雌性蟋蟀。在这两个科中，声音都是通过鸣叫来发出的，它们的前翅相互摩擦，这样一只翅膀的触须就会迅速越过另一只翅膀上的锯齿锉。产生的振荡被共振翼区放大。格里利德和tetigoniids的一个显著区别在于翅膀的形态和鸣声频率的组成：蟋蟀用高度对称的翅膀发出低频（2-8千赫）的纯音信号，而丛林蟋蟀则用不对称的翅膀发出高频（10-150千赫）的叫声。这种声学差异的进化原因尚不清楚。在这里，我们研究了主动鸣叫的雄性蟋蟀（Gryllus bimaculatus）的翅膀，并提出了振动声学数据，表明低频鸣叫的生物物理限制。利用激光多普勒振动仪（LDV）和脑内注射神经激活剂eserine来诱导鸣叫，我们记录了主动发声过程中翅膀振动的地形。在自由振动的机翼中，每个机翼区域的共振是不同的。当翅膀在鸣叫过程中耦合时，这些差异就消失了，所有的翅膀区域都以相同的频率共振，即窄带歌曲的频率（类似于5千赫）。然而，翼耦合的缺陷导致两个谐振器之间的相移，引入相位差增加的破坏性干涉。在蟋蟀的典型低频叫声中，通过保持振动相位差低于80度，观察到破坏性干扰（振幅降低）的影响最小。我们表明，由于观察到不完美的耦合，使用两个对称谐振器产生的蟋蟀歌曲在类似于8 kHz以上变得声学效率低下。这一证据揭示了在使用两个耦合谐振器时产生高频鸣声的生物力学约束，并解释了为什么蟋蟀不像丛林蟋蟀那样，没有进化到利用超声波鸣声的程度。
Male crickets and their close relatives bush-crickets (Gryllidae and Tettigoniidae, respectively; Orthoptera and Ensifera) attract distant females by producing loud calling songs. In both families, sound is produced by stridulation, the rubbing together of their forewings, whereby the plectrum of one wing is rapidly passed over a serrated file on the opposite wing. The resulting oscillations are amplified by resonating wing regions. A striking difference between Gryllids and Tettigoniids lies in wing morphology and composition of song frequency: Crickets produce mostly low-frequency (2-8 kHz), pure tone signals with highly bilaterally symmetric wings, while bush-crickets use asymmetric wings for high-frequency (10-150 kHz) calls. The evolutionary reasons for this acoustic divergence are unknown. Here, we study the wings of actively stridulating male field-crickets (Gryllus bimaculatus) and present vibro-acoustic data suggesting a biophysical restriction to low-frequency song. Using laser Doppler vibrometry (LDV) and brain-injections of the neuroactivator eserine to elicit singing, we recorded the topography of wing vibrations during active sound production. In freely vibrating wings, each wing region resonated differently. When wings coupled during stridulation, these differences vanished and all wing regions resonated at an identical frequency, that of the narrow-band song (similar to 5 kHz). However, imperfections in wing-coupling caused phase shifts between both resonators, introducing destructive interference with increasing phase differences. The effect of destructive interference (amplitude reduction) was observed to be minimal at the typical low frequency calls of crickets, and by maintaining the vibration phase difference below 80 degrees. We show that, with the imperfect coupling observed, cricket song production with two symmetric resonators becomes acoustically inefficient above similar to 8 kHz. This evidence reveals a bio-mechanical constraint on the production of high-frequency song whilst using two coupled resonators and provides an explanation as to why crickets, unlike bush-crickets, have not evolved to exploit ultrasonic calling songs.