In mammals, significant changes take place during postnatal growth, linked to changes in diet (from sucking to gnawing). During this period, mandible development is highly interconnected with muscle growth and the epigenetic interactions between muscle and bone control the spatialization of bone formation and remodelling in response to biomechanical strain. This mechanism contributes to postnatal developmental plasticity and may have influenced the course of evolutionary divergences between species and clades. We sought to model postnatal changes at a macroevolutionary scale by analysing ontogenetic trajectories of mandible shape across 16 species belonging mainly to two suborders of Rodents, Myomorpha and Hystricomorpha, which differ in muscle attachments, tooth growth and life-history traits. Myomorpha species present a much stronger magnitude of changes over a shorter growth period. Among Hystricomorpha, part of the observed adult shape is set up prenatally, and most postnatal trajectories are genus-specific, which agrees with nonlinear developmental trajectories over longer gestational periods. Beside divergence at large scale, we find some collinearities between evolutionary and developmental trajectories. A common developmental trend was also observed, leading to enlargement of the masseter fossa during postnatal growth. The tooth growth, especially hypselodonty, seems to be a major driver of divergences of postnatal trajectories. These muscle- and tooth-related effects on postnatal trajectories suggest opportunities for developmental plasticity in the evolution of the mandible shape, opportunities that may have differed across Rodent clades.

中文翻译：

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啮齿动物下颌骨形状个体发育的共性和进化差异。

在哺乳动物中，出生后生长过程中会发生显着变化，这与饮食的变化（从吮吸到啃咬）有关。在此期间，下颌骨发育与肌肉生长高度相关，肌肉和骨骼之间的表观遗传相互作用控制着响应生物力学应变的骨骼形成和重塑的空间化。这种机制有助于出生后的发育可塑性，并可能影响物种和进化枝之间进化分歧的过程。我们试图通过分析 16 个物种的下颌骨形状的个体发育轨迹，在宏观进化尺度上模拟出生后的变化，这些物种主要属于啮齿类动物的两个亚目，肌形目和狨形目，它们在肌肉附着、牙齿生长和生活史特征方面有所不同。Myomorpha 物种在较短的生长期内表现出更强的变化幅度。在 Hystricomorpha 中，部分观察到的成体形状是在出生前建立的，大多数出生后轨迹是属特异性的，这与较长妊娠期的非线性发育轨迹一致。除了大规模的分歧之外，我们还发现进化轨迹和发展轨迹之间存在一些共线性。还观察到共同的发育趋势，导致出生后生长过程中咬肌窝增大。牙齿的生长，尤其是前牙，似乎是产后轨迹差异的主要驱动因素。这些肌肉和牙齿相关对产后轨迹的影响表明下颌骨形状演变过程中存在发育可塑性的机会，