Oufiero Christopher E
Department of Biological Sciences, Towson University, Towson, Maryland, USA.
J Morphol. 2020 Apr;281(4-5):513-522. doi: 10.1002/jmor.21118. Epub 2020 Mar 27.
Limb proportions have evolved among animals to meet functional demands among diverse environments. Studies from terrestrial, vertebrate locomotion have demonstrated that variation in limb proportions have adaptively evolved so animals can perform in a given environment. Most of the research on limb proportion evolution is among vertebrates and terrestrial locomotion, with little information on limb segment evolution in invertebrates or for other functional roles. For example, among invertebrates, multisegmented raptorial forelimbs have evolved multiple times independently to capture prey, but there is little information on the adaptive evolution and diversity of these limbs. Furthermore, as feeding performance is influenced by the sensory system, few studies have examined the coevolution of sensory-motor systems. Using mantises (Mantodea) I examined forelimb diversification among 97 species with a combination of methods, including ternary plots for morphospace visualization, phylogenetically informed allometric relationships, and comparison of evolutionary rates of diversification. Furthermore, using head width as a proxy for depth perception, I examined the correlated evolution of foreleg diversity with depth perception. The results show that among the three segments of the foreleg, the tibia is the smallest, most diverse, and has the highest rate of evolution after body size corrections. Furthermore, while all foreleg segments were related to head width, head width explained the most variation in tibial length compared with other foreleg segments. The results suggest a potential adaptive functional role of tibia length related to the displacement or force produced in this mechanical lever. Furthermore, results from this study support distinct ecomorphs of mantises, as several independent evolutions to grass mimicry evolve similar morphologies. RESEARCH HIGHLIGHT: This study demonstrates interspecific variation among segments of an invertebrate raptorial foreleg. Among Mantodea species the tibia is the most diverse and is related to a proxy for depth perception, while the other segments had strong relationships with body size. This suggests an adaptive, functional role of the tibia during prey capture.
动物的肢体比例已经进化，以满足不同环境中的功能需求。陆地脊椎动物运动的研究表明，肢体比例的变化是适应性进化的结果，这样动物就能在特定环境中表现良好。大多数关于肢体比例进化的研究都集中在脊椎动物和陆地运动上，关于无脊椎动物肢体节段进化或其他功能作用的信息很少。例如，在无脊椎动物中，多节的捕食性前肢已经多次独立进化以捕获猎物，但关于这些肢体的适应性进化和多样性的信息很少。此外，由于摄食性能受感觉系统影响，很少有研究考察感觉运动系统的协同进化。我使用螳螂（螳螂目），结合多种方法研究了97个物种的前肢多样性，包括用于形态空间可视化的三元图、系统发育信息的异速生长关系以及多样化进化速率的比较。此外，我用头部宽度作为深度感知的指标，研究了前腿多样性与深度感知的协同进化。结果表明，在前腿的三个节段中，胫节最小、最多样化，在进行体型校正后进化速率最高。此外，虽然所有前腿节段都与头部宽度有关，但与其他前腿节段相比，头部宽度在前胫节长度上解释的变异最多。结果表明，胫节长度可能具有与该机械杠杆产生的位移或力相关的适应性功能作用。此外，这项研究的结果支持了螳螂不同的生态形态，因为几次独立进化出的拟草形态具有相似的形态。研究亮点：本研究展示了无脊椎动物捕食性前肢节段间的种间变异。在螳螂目物种中，胫节最多样化，与深度感知指标相关，而其他节段与体型有很强的关系。这表明胫节在捕食过程中具有适应性功能作用。
