The functional morphology of squamate fibrillar adhesive systems has been extensively investigated and has indirectly and directly influenced the design of synthetic counterparts. Not surprisingly, the structure and geometry of exemplar fibrils (setae) have been the subject of the bulk of the attention in such research, although variation in setal morphology along the length of subdigital adhesive pads has been implicated in the effective functioning of these systems. Adhesive setal field configuration has been described for several geckos, but that of the convergent Anolis lizards, comprised of morphologically simpler fibrils, remains largely unexplored. Here we examine setal morphology along the proximodistal axis of the digits of Anolis equestris and compare our findings to those for a model gecko, Gekko gecko. Consistent with previous work, we found that the setae of A. equestris are generally thinner, shorter, and present at higher densities than those of G. gecko and terminate in a single spatulate tip. Contrastingly, the setae of G. gecko are hierarchically branched in structure and carry hundreds of spatulate tips. Although the splitting of contacts into multiple smaller tips is predicted to increase the adhesive performance of a fiber compared to an unbranched one, we posited that the adhesive performance of G. gecko and A. equestris would be relatively similar when the configuration of the setal fields of each was accounted for. We found that, as in geckos, setal morphology of A. equestris follows a predictable pattern along the proximodistal axis of the pad, although there are several critical differences in the configuration of the setal fields of these two groups. Most notably, the pattern of variation in setal length of A. equestris is effectively opposite to that exhibited by G. gecko. This difference in clinal variation mirrors the difference in the direction in which the setal fields of anoles and geckos are peeled from the substrate, consistent with the hypothesis that biomechanical factors are the chief determinants of these patterns of variation. Future empirical work, however, is needed to validate this. Our findings introduce Anolis lizards as an additional source of inspiration for bio-inspired design and set the stage for comparative studies investigating the functional morphology of these convergent adhesive apparatuses. Such investigations will lead to an enhanced understanding of the interactions between form, function, and environment of fibril-based biological adhesive systems.

中文翻译：

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相同但不同：齿和壁虎的固定排列表明获得相似粘合效果的替代方法

鳞状纤维状胶粘剂体系的功能形态已被广泛研究，并间接和直接影响了合成对应物的设计。毫不奇怪，示例性原纤维（刚毛）的结构和几何形状一直是此类研究的重点，尽管沿亚指形胶垫长度方向的固定形态变化与这些系统的有效功能有关。已经描述了几种壁虎的粘着性固位场构型，但是在形态上较简单的原纤维组成的会聚的Anolis蜥蜴的构型在很大程度上仍未得到开发。在这里，我们检查沿Anolis equestris的手指的近轴的集合形态并将我们的发现与模型壁虎Gekko壁虎的发现进行比较。与以前的工作一致，我们发现马术曲柄的刚毛通常比壁虎气肿的菌毛更薄，更短并且以更高的密度存在，并终止于单个呈片状的尖端。相反，壁虎的刚毛科在结构上是分层分支的，并带有成百上千的扇形尖端。尽管将触点分成多个较小的尖端预计会比不分支的尖端提高纤维的粘合性能，但我们认为壁虎和A. equestris的粘合性能当考虑每个设置字段的配置时，将相对相似。我们发现，像壁虎一样，马术的固定形态沿垫的近前轴遵循可预测的模式，尽管这两组的固定场的配置存在一些关键差异。最显着的是，马术马齿set长度的变化模式实际上与壁虎G.展示的模式相反。渐进变化的这种差异反映了从底基剥落肛门和壁虎的实地电场方向的差异，这与生物力学因素是这些变化模式的主要决定因素的假设相一致。但是，需要未来的经验工作来验证这一点。我们的发现将Anolis蜥蜴作为生物启发设计的另一灵感来源，并为研究这些会聚粘合剂设备的功能形态的比较研究奠定了基础。这样的研究将导致对基于原纤维的生物粘合剂系统的形式，功能和环境之间的相互作用的加深了解。