Form-function relationships of head capsules of early split biting-chewing insects in a phylogenetic framework

有翼昆虫，如蜻蜓和蜉蝣（=古翅目），蚱蜢及其盟友（=多翅目）或棘虱（=棘目），大多具有相同的主要结构的咬咀嚼下颌骨。与基本口器结构的这种相对均匀性相反，头部胶囊在形状上表现出很大的变化。这种头囊形状多样性的原因、其对头部生物力学的影响以及最终与生态因素的可能相互作用尚不清楚。因此，该项目将对早期咬咀嚼昆虫中不同类型的头部胶囊进行机械研究，以评估不同的头部形状如何影响整体机械性能，并最终评估头部系统的进化适应性。总的假设是，在咬咀嚼昆虫中存在不同的形态和机制空间，它们更多地依赖于生态位而不是共同的祖先。此外，预计这些不同的机械空间在咬咀嚼进化过程中只允许有限数量的形状变化轨迹。广泛的古翅目、多翅目和棘翅目（约400种）的三维头部形状变化将用几何形态计量学进行定量分析。然后将对覆盖主要头囊形态的一个子集（约43个物种）进行生物力学模拟，使用多体动力学分析和有限元分析。材料特性、肌肉特性和咬力测量将作为生物力学建模的输入变量，以确保在计算机模型中准确表示体内力学。该项目将进一步考虑一般的生态位，如食物谱、狩猎类型等，以测试它们在系统发育框架内对头部力学和形状变化的影响。最后，将咬咀嚼的理论力学性能景观与真实物种所占据的实际性能景观进行建模，将有助于识别咬咀嚼系统进化和多样化过程中头部形状的变化轨迹和涉及的权衡。因此，研究结果将完善我们对昆虫进化的理解，该项目将确定哪些机械因素使昆虫如此成功地成为捕食者，以及它们的头部为何以及如何进化成如此多不同的类型。

Winged insects such as dragonflies and mayflies (=Palaeoptera), grasshoppers and allies (=Polyneoptera) or barklice (=Psocodea) mostly possess biting-chewing mandibles of the same principal construction. In contrast to this relative uniformity in basic mouthpart construction, head capsules show a great variety in shape. The reasons for this head capsule shape diversity, its consequences for head biomechanics and finally its likely interplay with ecological factors are unknown. The project will therefore investigate the variety of different head capsule types within early biting-chewing insects mechanically, in order to assess how different head shapes influence overall mechanical performance and, finally, the evolutionary fitness of the head system. The overall hypothesis is that distinct morpho- and mechanospaces within biting-chewing insects exist, which are more dependent on the ecological niche than on common ancestry. Moreover it is expected that these distinct mechanospaces permited only a limited number of shape change trajectories during the evolution of biting-chewing.The 3D head shape variation of a wide range of Palaeoptera, Polyneoptera and Psocodea (>400 species) will be quantitatively analysed with geometric morphometrics. Biomechanical simulation will then be carried out on a subset (~43 species) covering the main head capsule morphotypes using multibody dynamics analysis and finite element analysis. Material property, muscle property, and bite force measurements will serve as input variables for the biomechanical modelling to ensure an accurate representation of in vivo mechanics in the in silico models. The project will furthermore take into account the general ecological niche such as food spectrum, hunting type, etc. in order to test their influence on head mechanics and shape variation in a phylogenetic framework. Finally, modelling of the theoretical mechanical performance landscape of biting-chewing in relation to the actual performance landscape occupied by real species will allow to identify head shape change trajectories and involved trade-offs during the evolution and diversification of the biting-chewing system. The results will thus refine our understanding of insect evolution, with the project identifying which mechanical factors made insects such extraordinarily successful feeders, and why and how their heads evolved into so many different types.