Two developmental modules establish 3D beak-shape variation in Darwin's finches
Two developmental modules establish 3D beak-shape variation in Darwin's finches
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DOI：
10.1073/pnas.1011480108
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发表时间：
2011-03-08
影响因子：
11.1
通讯作者：
Abzhanov, Arhat
中科院分区：
文献类型：
--
作者：
Mallarino, Ricardo;Grant, Peter R.;Abzhanov, Arhat
鸟类喙在形状和大小上表现出巨大的变化，这与多种生态位的开发密切相关，并可能在数千种鸟类的多样化中发挥关键作用。先前的研究已经证明了一些调节鼻前软骨形态发生的分子机制，鼻前软骨形成了最初的喙骨骼。然而，鸟类喙的多样性很大程度上取决于前颌骨的变异。它形成于发育较晚的阶段，成为成人上喙/颌骨最突出的功能和结构成分，但其调节尚不清楚。在这里，我们研究了一组不同喙形状的达尔文雀类物种。我们发现，转化生长因子βIIR、β-连环素和Dickkopf-3这三个基因在不同喙形状物种胚胎发育中的上颌骨发育中存在差异表达。此外，我们的功能实验表明，这些分子形成了一个调控上颌骨形态的网络，它不同于控制前鼻软骨的网络，但具有相同的物种特异性表达区域。这些结果提供了潜在的机制，可以解释紧密耦合的深度和宽度维度如何独立进化。涉及独立调节分子的两个模块的发育计划为如何修改和组合不同的发育途径以诱导喙形态的多维变化提供了独特的见解。在发育过程中类似的模块化可能会在更大程度上表征其他生物体的复杂特征，而不是目前所认识到的程度。
Bird beaks display tremendous variation in shape and size, which is closely associated with the exploitation of multiple ecological niches and likely played a key role in the diversification of thousands of avian species. Previous studies have demonstrated some of the molecular mechanisms that regulate morphogenesis of the prenasal cartilage, which forms the initial beak skeleton. However, much of the beak diversity in birds depends on variation in the premaxillary bone. It forms later in development and becomes the most prominent functional and structural component of the adult upper beak/jaw, yet its regulation is unknown. Here, we studied a group of Darwin's finch species with different beak shapes. We found that TGF beta IIr, beta-catenin, and Dickkopf-3, the top candidate genes from a cDNA microarray screen, are differentially expressed in the developing premaxillary bone of embryos of species with different beak shapes. Furthermore, our functional experiments demonstrate that these molecules form a regulatory network governing the morphology of the premaxillary bone, which differs from the network controlling the prenasal cartilage, but has the same species-specific domains of expression. These results offer potential mechanisms that may explain how the tightly coupled depth and width dimensions can evolve independently. The two-module program of development involving independent regulating molecules offers unique insights into how different developmental pathways may be modified and combined to induce multidimensional shifts in beak morphology. Similar modularity in development may characterize complex traits in other organisms to a greater extent than is currently appreciated.