Department of Biology, Laboratory of Functional Morphology, University of Antwerp, Antwerp, Belgium.
Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium.
J Anat. 2019 Jul;235(1):1-14. doi: 10.1111/joa.12993. Epub 2019 Apr 17.
The vestibular system is crucial for movement control during locomotion. As the dimensions of the vestibular system determine the fluid dynamics of the endolymph and, as such, the system's function, we investigate the interaction between vestibular system size, head size and microhabitat use in lizards. We grouped 24 lacertid species in three microhabitat types, we acquired three-dimensional models of the bony vestibular systems using micro-computer tomography scanning, and we performed linear and surface measurements. All vestibular measurements scale with a negative allometry with head size, suggesting that smaller heads house disproportionally large ears. As the sensitivity of the vestibular system is positively related to size, a sufficiently large vestibular system in small-headed animals may meet the sensitivity demands during challenged locomotion. We also found that the microhabitat affects the locomotor dynamics: lizards inhabiting open microhabitats run at higher dimensionless speeds. On the other hand, no statistical relationship exists between dimensionless speed and the vestibular system dimensions. Hence, if the vestibular size would differ between microhabitats, this would be a direct effect (i.e. imposed, for instance, by requirements for manoeuvring, balance control, etc.), rather than depending on the lizards' intrinsic running speed. However, we found no effect of the microhabitat on the allometric relationship between head and vestibular system size. The finding that microhabitat is not reflected in the vestibular system size (hence sensitivity) of the lacertids in this study is possibly due to spatial constraints of the skull.
前庭系统对于运动控制至关重要。由于前庭系统的尺寸决定了内淋巴的流体动力学，进而决定了系统的功能，因此我们研究了蜥蜴前庭系统大小、头部大小和小生境使用之间的相互作用。我们将 24 种蜥蜴物种分为三种小生境类型，使用微计算机断层扫描技术获取骨骼前庭系统的三维模型，并进行了线性和表面测量。所有前庭测量都与头部大小呈负异速关系，这表明较小的头部容纳不成比例大的耳朵。由于前庭系统的灵敏度与尺寸呈正相关，因此在小头部动物中，足够大的前庭系统可能能够满足在挑战性运动中对灵敏度的需求。我们还发现小生境会影响运动动力学：生活在开阔小生境中的蜥蜴以更高的无维速度奔跑。另一方面，无维速度与前庭系统尺寸之间不存在统计学关系。因此，如果小生境之间的前庭大小存在差异，这将是一种直接影响（例如，由于对操纵、平衡控制等的要求而产生的影响），而不是取决于蜥蜴的固有奔跑速度。然而，我们没有发现小生境对头部和前庭系统大小之间的异速关系产生影响。在本研究中，蜥蜴的小生境没有反映在其前庭系统大小（因此灵敏度）中，这可能是由于头骨的空间限制。
