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Origins and evolutionary consequences of a genetic mechanism for developmental plasticity

发育可塑性遗传机制的起源和进化后果

基本信息

批准号：
1911688
负责人：
Erik Ragsdale
金额：
$ 86万
依托单位：
Indiana University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-08-01 至 2023-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1911688&HistoricalAwards=false
关键词：
Origins evolutionary consequences genetic mechanism

项目摘要

Environmentally induced variability, or 'developmental plasticity', offers a way for animals and plants to "match" their traits, at least to some degree, to their surroundings. In extreme cases, this variability results in disparate, alternative forms. Although plasticity in general is common in animals and plants, very few examples of how environments cause "switches" between alternative trait outcomes are understood at the level of genes. It is even more obscure how the internal genetic machinery for a switch arises in evolution. Furthermore, what consequences this flexibility has for the natural selection of traits, which take different forms under different conditions, are not well understood, due to our limited understanding of the genes involved in the switches and what these switches act on. In this research, the nematode Pristionchus pacificus and several related species - which assume different feeding-forms in response to starvation and local competition for food - will be used to determine how genes have come together in evolutionary history to form a switch that mediates developmental plasticity. A comparative approach will be used infer what effects this switch has had on the genes, and ultimately the traits, it influences. In addition, the investigators will train undergraduate, graduate, and postdoctoral students in research integrating genetics, developmental biology, and evolution, and it will support two science-outreach programs at Indiana University: (i) the PI will host and mentor underrepresented minority high-school students in their own research projects in an annual summer program; (ii) the PI will help Indiana high-school teachers to develop and implement projects, experiments, and activities as classroom resources to improve the teaching and learning of state life science standards.This research will advance a functional genetic understanding of developmental plasticity, specifically of its regulatory and target genes, and it will provide the necessary framework for understanding both the mechanistic evolution and the evolutionary significance of polyphenism, i.e., discrete developmental plasticity. First, it will describe how nutritional sensing interfaces with the polyphenism switch in the nematode model Pristionchus pacificus. This aim will be met by functional tests of switch components, particularly genes isolated from a forward screen for polyphenism mutants. Second, the research will reconstruct the evolutionary history of an integrated switch mechanism for the mouth polyphenism in P. pacificus and other species in its family (Diplogastridae). This aim will be met by comparative reverse genetics and transgenic experiments. Third, it will determine the molecular consequences of polyphenism and its loss across diplogastrid nematodes. This aim will be met by molecular evolutionary analyses of polyphenism target genes. In summary, the research will integrate a model for polyphenism genetics into a phylogenetic framework of several lineages characterized by plastic - and secondarily assimilated morphologies. Specifically, the research will establish a model for polyphenism that encompasses: (i) the mechanistic requirements for its origin; (ii) the molecular capacities for its regulation to change; and (iii) its proximate (genetic) and ultimate (evolutionary) consequences.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.

环境引起的变异性或“发育可塑性”为动植物提供了一种使其特征（至少在某种程度上）与周围环境“匹配”的方法。在极端情况下，这种可变性会导致不同的替代形式。尽管可塑性在动物和植物中普遍存在，但在基因水平上了解环境如何导致替代性状结果之间“转换”的例子却很少。更令人费解的是，开关的内部遗传机制是如何在进化过程中产生的。此外，由于我们对开关所涉及的基因以及这些开关的作用的了解有限，这种灵活性对在不同条件下采取不同形式的性状的自然选择有何影响尚不清楚。在这项研究中，太平洋Pristionchus线虫和几个相关物种——它们为了应对饥饿和局部食物竞争而采取不同的进食形式——将被用来确定基因在进化史上如何聚集在一起，形成介导发育可塑性的开关。将使用比较方法来推断这种开关对基因以及最终对其影响的性状产生的影响。此外，研究人员还将培训本科生、研究生和博士后学生进行遗传学、发育生物学和进化论相结合的研究，并将支持印第安纳大学的两个科学推广项目：(i) PI 将在年度暑期项目中接待和指导少数族裔高中生参与他们自己的研究项目； (ii) PI 将帮助印第安纳州高中教师开发和实施项目、实验和活动，作为课堂资源，以改善国家生命科学标准的教学和学习。这项研究将推进对发育可塑性的功能遗传学理解，特别是其调节和目标基因，并将为理解多态性（即离散发育可塑性）的机械进化和进化意义提供必要的框架。首先，它将描述营养传感如何与线虫模型 Pristionchus pacificus 中的多型开关相互作用。这一目标将通过开关组件的功能测试来实现，特别是从多型突变体的正向筛选中分离出的基因。其次，该研究将重建太平洋对虾及其科（双腹科）其他物种的口多型性综合开关机制的进化历史。这一目标将通过比较反向遗传学和转基因实验来实现。第三，它将确定多型现象的分子后果及其在双足线虫中的损失。这一目标将通过多型性目标基因的分子进化分析来实现。总之，该研究将把多型遗传学模型整合到几个以可塑和二次同化形态为特征的谱系的系统发育框架中。具体来说，该研究将建立一个多型现象模型，其中包括：（i）其起源的机械要求； (ii) 其调节的分子能力发生变化；该奖项反映了 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。