Closely related bird species demonstrate flexibility between beak morphology and underlying developmental programs
Closely related bird species demonstrate flexibility between beak morphology and underlying developmental programs
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DOI：
10.1073/pnas.1206205109
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发表时间：
2012-10-02
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;Campas, Otger;Abzhanov, Arhat
鸟喙形状和大小的惊人变化反映了广泛的饮食专业化，这些专业化在鸟类多样化中发挥了重要作用。在达尔文的雀类中，地雀(Geospiza spp.)具有代表相同形状的比例变化的喙，这是由于调节喙的两个骨骼成分：鼻前软骨(PNC)和前颌骨(PMX)的信号通路的变化而产生的。然而，这种发育机制是否对其他密切相关的鸟类种群内的差异负责仍不清楚。在这里，我们报道了与达尔文雀类关系密切的加勒比海牛头雀(Loxigilla spp.)，它们独立进化出了一种新形状的喙，与Geospiza不同，但也只是在比例上有所不同。然而，尽管有相同的喙形状，但信号通路和形成Loxigilla喙图案的组织在这三个物种中是不同的。在Loxigilla noctis中，与Geospiza中一样，PNC首先由Bmp4和CaM信号形成，然后是PMX的发育，受转化生长因子βIIR、β-连环蛋白和Dkk3信号的调节。相比之下，紫罗兰和港口洛克希拉喙的形态发生几乎完全是由PMX通过IHH和Bmp4协同促进骨组织扩张的机制产生的。总之，我们的结果表明，形态和潜在的发展原因之间的关系具有很高的灵活性，不同的发展计划可以产生相同的形状，而相似的发展计划可以形成不同的形状。
The astonishing variation in the shape and size of bird beaks reflects a wide range of dietary specializations that played an important role in avian diversification. Among Darwin's finches, ground finches (Geospiza spp.) have beaks that represent scaling variations of the same shape, which are generated by alterations in the signaling pathways that regulate growth of the two skeletal components of the beak: the prenasal cartilage (pnc) and the premaxillary bone (pmx). Whether this developmental mechanism is responsible for variation within groups of other closely related bird species, however, has remained unknown. Here, we report that the Caribbean bullfinches (Loxigilla spp.), which are closely related to Darwin's finches, have independently evolved beaks of a novel shape, different from Geospiza, but also varying from each other only in scaling. However, despite sharing the same beak shape, the signaling pathways and tissues patterning Loxigilla beaks differ among the three species. In Loxigilla noctis, as in Geospiza, the pnc develops first, shaped by Bmp4 and CaM signaling, followed by the development of the pmx, regulated by TGF beta IIr, beta-catenin, and Dkk3 signaling. In contrast, beak morphogenesis in Loxigilla violacea and Loxigilla portoricensis is generated almost exclusively by the pmx through a mechanism in which Ihh and Bmp4 synergize to promote expansion of bone tissue. Together, our results demonstrate high flexibility in the relationship between morphology and underlying developmental causes, where different developmental programs can generate identical shapes, and similar developmental programs can pattern different shapes.