Microevolution of molecular mechanisms for developmental plasticity in Pristionchus nematodes

基因本身并不能决定性状，在动物和植物中普遍存在的现象是性状会因环境的不同压力而产生不同的发育。这种现象被称为“发育可塑性”，在某些极端情况下，它在不同的形式之间起到了“切换”的作用。在一些例子中，这种开关被定义为个体基因和它们编码的产物。然而，一个持久的挑战是理解这些开关，特别是负责的分子过程，是如何在自然界中进化的。本研究的目的是利用不同种类的线虫对饥饿和本地竞争采取不同的进食形式，以确定发育可塑性进化的遗传基础。此外，通过利用人口之间可塑性的多种互补类型的变化，该项目将确定哪些特征（如果有的话）可以在他们之间推广。该项目将培养整合遗传学、发育生物学和进化的本科生、研究生和博士后。该研究还将支持印第安纳大学的两个科学推广项目：(i)调查实验室将在年度暑期项目中接待和指导代表性不足的少数族裔高中生进行自己的研究项目；（ii）首席研究员将指导印第安纳高中教师开发项目、实验和活动，并在课堂上实施，以提高州生命科学标准的教学和学习。这项研究将促进对多表型或离散发育可塑性进化的功能遗传学理解。利用线虫发育遗传学模型系统，本研究将形态多表型的定义分子机制与解释多表型自然变异的等位基因变异联系起来。首先，本研究将确定太平洋Pristionchus野生分离株间塑性反应差异的定量遗传基础。这一目标将通过映射、验证和功能表征导致对环境阈值反应差异的等位变异来实现。其次，确定具有相似塑性反应的野生分离株间多表型调控隐性差异的定量遗传基础。这一目标将通过揭示通过越界表型发现的变异组合如何导致多表型进化来实现。第三，通过实验确定塑性演化近端机制的可重复性。这一目标将通过复制实验进化情景来实现，以响应多物化影响环境。通过将多表型遗传学模型整合到微观进化框架中，本研究将描述：(i)多表型调控机制变化的分子能力；（ii）在平行的分歧案例中，变化的类型有多普遍；（iii）不同的可塑性调节剂对多表型发育网络的影响，包括那些影响最终形态产生的成分。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Genes alone do not determine traits, and a widespread phenomenon in animals and plants is for traits to develop differently in response to varying pressures from the environment. This phenomenon is known as “developmental plasticity,” which in some extreme cases acts as a “switch” between alternative and often strikingly different forms. In some examples, such switches have been defined in terms of individual genes and the products they encode. However, a persistent challenge has been to understand how these switches, specifically the molecular processes responsible, evolve in nature. The goal of this research is to identify, using species of nematodes that assume different feeding-forms in response to starvation and local competition, the genetic basis for how developmental plasticity evolves. Moreover, by drawing on multiple, complementary types of variation in plasticity among populations, the project will determine which features, if any, are generalizable across them. The project will train undergraduate, graduate, and postdoctoral students in research that integrates genetics, developmental biology, and evolution. The research will also support two science-outreach programs at Indiana University: (i) the investigating laboratory will host and mentor underrepresented minority high-school students in their own research projects in an annual summer program, and (ii) the principal investigator will guide Indiana high-school teachers in developing projects, experiments, and activities to be implemented in the classroom to improve the teaching and learning of state life-science standards.This research will advance a functional-genetic understanding of the evolution of polyphenism, or discrete developmental plasticity. Using a model system for developmental genetics, Pristionchus nematodes, this research will link defined molecular mechanisms of a morphological polyphenism to the allelic variants that explain natural variation in that polyphenism. First, the research will determine the quantitative genetic basis for observed divergence of plastic responses between wild isolates of the species Pristionchus pacificus. This aim will be met by mapping, validating, and functionally characterizing allelic variants causing differences in a threshold response to the environment. Second, the research will determine the quantitative genetic basis for hidden divergence of polyphenism regulation between wild isolates with similar plastic responses. This aim will be met by revealing how combinations of variants, which can be uncovered through transgressive phenotypes, are responsible for polyphenism evolution. Third, the research will experimentally determine the repeatability of proximal mechanisms for plasticity evolution. This aim will be met by replicating scenarios of experimental evolution of Pristionchus populations in response to a polyphenism-influencing environment. By integrating a model for polyphenism genetics into a microevolutionary framework, the research will describe: (i) the molecular capacity of polyphenism’s regulatory mechanisms to change; (ii) how generalizable the types of changes are across parallel cases of divergence; (iii) the impact of diverging plasticity modifiers on the polyphenism developmental network, including those components that effect the ultimate forms produced.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.