Mammalian molar complexity follows simple, predictable patterns
Mammalian molar complexity follows simple, predictable patterns
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DOI：
10.1073/pnas.2008850118
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发表时间：
2021-01-05
影响因子：
11.1
通讯作者：
Silcox, Mary T.
中科院分区：
文献类型：
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作者：
Selig, Keegan R.;Khalid, Waqqas;Silcox, Mary T.
确定复杂结构（如哺乳动物臼齿）进化的发育解释是研究表型变异的基础。先前的研究表明，摩尔比例的“形态发生梯度”被解释为早期发育磨牙的抑制/激活活性之间的平衡，称为抑制级联模型（ICM）。虽然这个模型为摩尔比例的变化提供了解释，但仍然知之甚少的是，如果摩尔形状，或特别是复杂性（即，尖、峰的数量），可以用相同的发育模型来解释。在这里，我们表明，磨牙的复杂性符合ICM，以下的线性，形态发生梯度沿着磨牙行。此外，不同水平的抑制/激活活性产生对比模式的摩尔复杂性取决于饮食。这项研究证实了磨牙复杂性的进化模型，该模型在发育上是简单的，仅需要发生小规模的发育变化就可以在整个磨牙行中产生变化，该过程由动物的生态学介导。因此，ICM提供了一个发展的框架来解释摩尔复杂性的变化，并在更广泛的哺乳动物进化背景下测试发展假说的手段。
Identifying developmental explanations for the evolution of complex structures like mammalian molars is fundamental to studying phenotypic variation. Previous study showed that a "morphogenetic gradient" of molar proportions was explained by a balance between inhibiting/activating activity from earlier developing molars, termed the inhibitory cascade model (ICM). Although this model provides an explanation for variation in molar proportions, what remains poorly understood is if molar shape, or specifically complexity (i.e., the number of cusps, crests), can be explained by the same developmental model. Here, we show that molar complexity conforms to the ICM, following a linear, morphogenetic gradient along the molar row. Moreover, differing levels of inhibiting/activating activity produce contrasting patterns of molar complexity depending on diet. This study corroborates a model for the evolution of molar complexity that is developmentally simple, where only small-scale developmental changes need to occur to produce change across the entire molar row, with this process being mediated by an animal's ecology. The ICM therefore provides a developmental framework for explaining variation in molar complexity and a means for testing developmental hypotheses in the broader context of mammalian evolution.