Microevolution of molecular mechanisms for developmental plasticity in Pristionchus nematodes

基因本身并不能决定性状，动物和植物中的一个普遍现象是，性状会根据环境的不同压力而不同地发展。这种现象被称为“发育可塑性”，在某些极端情况下，它充当了替代形式之间的“开关”，而且往往是惊人的不同形式。在一些实例中，此类开关已经根据个体基因和它们编码的产物来定义。然而，一个持续的挑战是了解这些开关，特别是负责的分子过程，在自然界中如何演变。本研究的目的是确定，利用线虫的物种，假设不同的喂养形式，在响应饥饿和本地竞争，发育可塑性如何演变的遗传基础。此外，通过利用种群之间可塑性的多种互补类型的变异，该项目将确定哪些特征（如果有的话）可以在它们之间推广。该项目将在整合遗传学、发育生物学和进化的研究中培养本科生、研究生和博士后。该研究还将支持印第安纳州大学的两个科学推广项目：（i）调查实验室将在每年的暑期项目中主持和指导代表性不足的少数民族高中学生进行自己的研究项目，（ii）首席研究员将指导印第安纳州高中教师开发项目，实验，以及在课堂上实施的活动，以提高国家生命科学标准的教学和学习。这项研究将推进对多型性或离散发育可塑性进化的功能遗传理解。使用发育遗传学的模型系统，Pristionchus线虫，这项研究将连接定义的分子机制的形态多型性的等位基因变异，解释自然变异的多型性。首先，这项研究将确定观察到的物种太平洋棱纹瓢虫野生菌株之间的塑料反应分歧的定量遗传基础。这一目标将通过映射、验证和功能表征导致对环境的阈值响应差异的等位基因变体来实现。其次，本研究将确定具有相似可塑性反应的野生菌株之间多型性调节的隐藏分歧的数量遗传基础。这一目标将通过揭示如何组合的变体，这可以通过超进表型发现，负责多型进化。第三，这项研究将通过实验确定可塑性演化的近端机制的可重复性。这一目标将通过复制实验进化的Pristionchus种群在一个多相影响的环境中的情景来实现。通过将一个多型遗传学模型整合到一个微进化框架中，该研究将描述：（i）多型调节机制改变的分子能力;（ii）在平行的分歧情况下，变化类型的可推广性如何;（iii）不同可塑性调节剂对多型性发育网络的影响，该奖项反映了NSF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.