Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Kiel, Germany
Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
J R Soc Interface. 2018 Jun;15(143). doi: 10.1098/rsif.2018.0281.
In its evolution, the diverse group of stick and leaf insects (Phasmatodea) has undergone a rapid radiation. These insects evolved specialized structures to adhere to different surfaces typical for their specific ecological environments. The cuticle of their tarsal attachment pads (euplantulae) is known to possess a high diversity of attachment microstructures (AMS) which are suggested to reflect ecological specializations of different groups within phasmids. However, the origin of these microstructures and their developmental background remain largely unknown. Here, based on the detailed scanning electron microscopy study of pad surfaces, we present a theoretical approach to mathematically model an outstanding diversity of phasmid AMS using the reaction-diffusion model by Alan Turing. In general, this model explains pattern formation in nature. For the first time, we were able to identify eight principal patterns and simulate the transitions among these. In addition, intermediate transitional patterns were predicted by the model. The ease of transformation suggests a high adaptability of the microstructures that might explain the rapid evolution of pad characters. We additionally discuss the functional morphology of the different microstructures and their assumed advantages in the context of the ecological background of species.
在进化过程中，形态各异的竹节虫目（Phasmatodea）经历了快速辐射。这些昆虫进化出了专门的结构，以附着在与其特定生态环境相关的不同表面上。已知它们跗节附肢垫（euplantulae）的表皮具有高度多样化的附着微观结构（AMS），这些结构被认为反映了不同组群在竹节虫目内的生态特化。然而，这些微观结构的起源及其发育背景在很大程度上仍然未知。在这里，我们基于对垫表面的详细扫描电子显微镜研究，提出了一种理论方法，即使用艾伦·图灵的反应扩散模型，用数学模型来模拟竹节虫目 AMS 的多样性。一般来说，这个模型可以解释自然界中的模式形成。我们首次能够识别出八种主要模式，并模拟它们之间的转变。此外，该模型还预测了中间过渡模式。这些微观结构的易于转换表明了它们具有高度的适应性，这可能解释了垫特征的快速进化。我们还讨论了不同微观结构的功能形态及其在物种生态背景下的假设优势。
