Microevolution of molecular mechanisms for developmental plasticity in Pristionchus nematodes

基因本身并不能决定性状，动植物中普遍存在的现象是，性状在应对来自环境的不同压力时会有不同的发展。这种现象被称为“发育可塑性”，在某些极端情况下，它充当另一种形式之间的“开关”，而且往往是截然不同的形式。在一些例子中，这种开关是根据单个基因及其编码的产物来定义的。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。这项研究的目的是利用对饥饿和当地竞争采取不同取食形式的线虫物种，确定发育可塑性如何演变的遗传基础。此外，通过利用种群间多种互补类型的可塑性差异，该项目将确定哪些特征(如果有的话)可在它们之间推广。该项目将培训本科生、研究生和博士后，进行整合遗传学、发育生物学和进化论的研究。这项研究还将支持印第安纳大学的两个科学推广项目：(I)调查实验室将在一年一度的暑期项目中接待和指导未被充分代表的少数族裔高中生进行他们自己的研究项目，以及(Ii)首席调查员将指导印第安纳州高中教师开发项目、实验和活动，并在课堂上实施，以提高州生命科学标准的教和学。这项研究将促进对多面性或离散发展可塑性进化的功能遗传学的理解。这项研究利用发育遗传学的模型系统--Pristionchus Nematodes，将确定的形态多态的分子机制与解释这种多态的自然变异的等位基因变异联系起来。首先，这项研究将确定观察到的太平洋Pristionchus野生分离株之间塑料反应差异的数量遗传基础。这一目标将通过对引起环境阈值反应差异的等位基因变异进行定位、验证和功能表征来实现。其次，这项研究将确定具有相似塑料反应的野生菌株之间多态调控隐藏差异的数量遗传基础。这一目标将通过揭示通过侵入式表型发现的变异组合如何导致多物性进化来实现。第三，这项研究将在实验上确定塑性进化的近端机制的重复性。这一目标将通过复制Pristionchus种群实验进化的情景来实现，以响应多种性影响的环境。通过将多性遗传模型整合到一个微进化框架中，这项研究将描述：(I)多性遗传调控机制的分子能力；(Ii)在不同的平行情况下，这种变化的类型有多普遍；(Iii)不同的可塑性修饰物对多性发育网络的影响，包括那些影响最终形式的成分。这一奖项反映了NSF的法定使命，并通过使用基金会的智力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.