Regulators of an ancient polyphenism evolved through episodic protein divergence and parallel gene radiations
Regulators of an ancient polyphenism evolved through episodic protein divergence and parallel gene radiations
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DOI：
10.1098/rspb.2019.2595
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发表时间：
2020-02-26
影响因子：
4.7
通讯作者：
Ragsdale, Erik J.
中科院分区：
文献类型：
--
作者：
Biddle, Joseph F.;Ragsdale, Erik J.
多型性是发育可塑性的一种形式，它将环境线索转换成不连续的，通常是完全不同的表型。在某些情况下，多型性被归因于促进形态多样化，甚至新性状的进化。然而，这一过程是基于指定替代发育网络的遗传机制的起源和进化维护。何时以及如何调节基因座出现和变化，特别是之前和整个历史的多型性，是很少了解的。在这里，我们为两个动态进化的基因eud-1和seud-1建立了系统发育和比较分子背景，这两个基因调节太平洋扁尾线虫的多效现象。该物种在其成年摄食结构中具有二型性，允许个体根据环境而成为微食动物或兼性捕食者。虽然多型性调节在太平洋拟步行虫中越来越被理解，但多型性比这个物种要古老得多，并且在形态上多样化，以使多型谱系中的一系列生态功能成为可能。为了将这种分类学上的多样性纳入比较范围，我们重建了eud-1和seud-1相对于多型性起源和多样性的历史，发现这两个基因的同源物在多型分类群中经历了谱系特异性辐射。此外，我们发现了eud-1的情景多样化选择的签名，特别是在早期的双腹类谱系。最后，转基因拯救实验表明，该基因的产品在功能上偏离了它的直系同源物在一个非多表型外群。总之，我们提供了一个可塑性开关的分子组成的比较框架，使研究多型性，其调节，并最终其目标的演变。
Polyphenism is a form of developmental plasticity that transduces environmental cues into discontinuous, often disparate phenotypes. In some cases, polyphenism has been attributed to facilitating morphological diversification and even the evolution of novel traits. However, this process is predicated on the origins and evolutionary maintenance of genetic mechanisms that specify alternate developmental networks. When and how regulatory loci arise and change, specifically before and throughout the history of a polyphenism, is little understood. Here, we establish a phylogenetic and comparative molecular context for two dynamically evolving genes, eud-1 and seud-1, which regulate polyphenism in the nematode Pristionchus pacificus. This species is dimorphic in its adult feeding-structures, allowing individuals to become microbivores or facultative predators depending on the environment. Although polyphenism regulation is increasingly well understood in P. pacificus, the polyphenism is far older than this species and has diversified morphologically to enable an array of ecological functions across polyphenic lineages. To bring this taxonomic diversity into a comparative context, we reconstructed the histories of eud-1 and seud-1 relative to the origin and diversification of polyphenism, finding that homologues of both genes have undergone lineage-specific radiations across polyphenic taxa. Further, we detected signatures of episodic diversifying selection on eud-1, particularly in early diplogastrid lineages. Lastly, transgenic rescue experiments suggest that the gene's product has functionally diverged from its orthologue's in a non-polyphenic outgroup. In summary, we provide a comparative framework for the molecular components of a plasticity switch, enabling studies of how polyphenism, its regulation, and ultimately its targets evolve.