Protrusile jaws are a highly useful innovation that has been linked to extensive diversification in fish feeding ecology. Jaw protrusion can enhance the performance of multiple functions, such as suction production and capturing elusive prey. Identifying the developmental factors that alter protrusion ability will improve our understanding of fish diversification. In the zebrafish protrusion arises postmetamorphosis. Fish metamorphosis typically includes significant changes in trophic morphology, accompanies a shift in feeding niche and coincides with increased thyroid hormone production. We tested whether thyroid hormone affects the development of zebrafish feeding mechanics. We found that it affected all developmental stages examined, but that effects were most pronounced after metamorphosis. Thyroid hormone levels affected the development of jaw morphology, feeding mechanics, shape variation, and cranial ossification. Adult zebrafish utilize protrusile jaws, but an absence of thyroid hormone impaired development of the premaxillary bone, which is critical to jaw protrusion. Premaxillae from early juvenile zebrafish and hypothyroid adult zebrafish resemble those from adults in the genera Danionella, Devario, and Microdevario that show little to no jaw protrusion. Our findings suggest that evolutionary changes in how the developing skulls of danionin minnows respond to thyroid hormone may have promoted diversification into different feeding niches.

中文翻译：

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斑马鱼发育过程中的甲状腺激素调节概括了丹尼酸下颌突出机制的进化多样性。

突出的颚是一项非常有用的创新，与鱼类饲养生态的广泛多样化有关。下巴突出可以增强多种功能的性能，例如吸力产生和捕捉难以捉摸的猎物。确定改变突出能力的发育因素将提高我们对鱼类多样化的理解。斑马鱼的突起是在变态后出现的。鱼类变态通常包括营养形态的显着变化，伴随着摄食生态位的变化，并且与甲状腺激素产生的增加同时发生。我们测试了甲状腺激素是否影响斑马鱼摄食机制的发育。我们发现它影响所有检查的发育阶段，但这种影响在变态后最为明显。甲状腺激素水平影响颌部形态的发育、进食机制、形状变化和颅骨骨化。成年斑马鱼利用突出的下颌，但甲状腺激素的缺乏会损害前颌骨的发育，而前颌骨的发育对于下颌突出至关重要。早期幼年斑马鱼和甲状腺功能减退的成年斑马鱼的前颌骨与丹尼拉鱼属、德瓦里奥属和微德瓦里奥属成年斑马鱼的前颌骨相似，下颌几乎没有突出。我们的研究结果表明，丹尼酸米诺鱼正在发育的头骨对甲状腺激素的反应方式的进化变化可能促进了其向不同摄食环境的多样化。