Fish skulls are often highly kinetic, with multiple linkage and lever systems powered by a diverse suite of muscles. Comparative analysis of the evolution of soft-tissue structures in the fish skull is often limited under traditional approaches, while new imaging techniques like diceCT (diffusible iodine-based contrast-enhanced computed tomography) allow for high-resolution imaging of muscles in situ. Darters (Percidae: Etheostomatinae) are a diminutive and species-rich clade of lotic freshwater fishes, which show diverse head shapes believed to be associated with different foraging strategies. We used diceCT to sample all major cranial adductors and abductors responsible for movement of the jaw, hyoid, operculum, and suspensorium from 29 species. We applied comparative phylogenetic approaches to analyse the evolutionary trends in muscle size across the clade. We found two major patterns: (i) darter cranial muscles show fundamental trade-offs relating to investment in musculature, as well as buccal expansion vs. biting attributes; early divergence in muscle size appears to be associated with shifts in habitat use and foraging; (ii) darter adductor mandibulae show high variation in architecture (fibre orientation, divisions). This study highlights how new imaging techniques can provide novel insights into the anatomy of even well-sampled/represented clades.

中文翻译：

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镖鱼颅骨肌肉组织（Etheostomatinae：Percidae）的适应和创新：来自 diceCT 的见解


鱼的头骨通常具有高度的运动性，具有由各种肌肉提供动力的多个连杆和杠杆系统。在传统方法下，对鱼头骨软组织结构演变的比较分析通常受到限制，而 diceCT（基于弥散碘的造影剂增强计算机断层扫描）等新的成像技术允许对肌肉进行原位高分辨率成像。镖鱼 （Percidae： Etheostomatinae） 是一个体型小且物种丰富的垂钓淡水鱼分支，它们表现出不同的头部形状，被认为与不同的觅食策略有关。我们使用 diceCT 对 29 个物种中负责颌骨、舌骨、鳃盖和悬吊运动的所有主要颅内收肌和外展肌进行采样。我们应用比较系统发育方法来分析整个分支肌肉大小的进化趋势。我们发现了两个主要模式：（i） 镖颅肌显示出与肌肉组织投资以及颊侧扩张与咬合属性相关的基本权衡;肌肉大小的早期分化似乎与栖息地利用和觅食的变化有关;（ii） 镖内收肌下颌骨在结构上表现出高度变化（纤维方向、分裂）。这项研究强调了新的成像技术如何为即使是采样良好/代表性的进化枝的解剖结构提供新的见解。