SG: The adaptive (and maladaptive) consequences of non-additive genetic variation

了解生物如何适应环境的遗传基础和潜在限制，在生物学的许多领域都是至关重要的。例如，这些知识可以改进作物育种，并可以改进对本地和农艺物种对气候变化的反应的预测。目前关于适应遗传学的知识主要局限于遗传变异的一个子集，其中一个基因的不同拷贝（等位基因）对生存和繁殖的影响是加性的，可以简单地加在一起。然而，等位基因对生物体的影响可能取决于同一基因或不同基因的其他等位基因的存在，以及环境条件。其中一个例子是杂种优势，当不同品系的植物交配时，通常会产生杂交后代，这些后代比亲本中的任何一个品系都有更好的存活率和更好的制种能力。拟议的研究使用一套独特的遗传资源来量化这些非加性效应对生存和种子生产的贡献。将与K-12学生开展有关气候变化的适应和不适应主题的外展活动。尽管对适应遗传学的研究已经进行了近一个世纪，但我们对非加性遗传变异对适应的贡献知之甚少，不适应基因座存在的适应程度，以及这种平衡如何随着环境变化而改变。本研究将确定杂种优势（杂种活力）和杂种优势与环境相互作用的遗传基础，量化上位性在适应分化中的作用，并确定拮抗基因座在本地适应群体之间的杂交中促进过侵分离的程度。对来自意大利和瑞典的两种生态型拟南芥在原生地长期适合度的遗传基础进行的基础研究揭示了一个复杂的遗传基础，包括上位性、适应和不适应等位基因的混合以及瑞典适合度的越界分离。在这些生态型之间的杂交中，显性有助于杂种优势，有限的遗传变异和高杂种优势是北方种群的特征。该研究将利用一组近等基因系（NILs）来产生纯合子、杂合子和组合渗入片段。为了研究杂种优势、上位性和附加互补对适应度的影响，这些品系的适应度成分将在模拟本地环境的生长室内进行分析，并根据十多年的现场气候和适应度数据进行设计和优化。培训将为研究生和本科生提供，他们也将参加K-12外展活动。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。

Understanding the genetic basis, and potential limitations, of how organisms adapt to their environment is fundamentally important in many areas of biology. For example, such knowledge can improve crop breeding and can improve predictions about responses to climatic variability in both native and agronomic species. Current knowledge about the genetics of adaptation is mostly limited to a subset of genetic variation, where the effects of different copies (alleles) of a gene on survival and reproduction are additive and can simply be summed together. However, the effects of alleles on the organism can depend on the presence of other alleles for the same gene or different genes, and on environmental conditions. One example of this is called hybrid vigor, which often occurs when mating together plants of different strains, and results in hybrid offspring that have better survival and better seed production than either parent strain. The proposed research uses a unique set of genetic resources to quantify the contribution of these non-additive effects on survival and seed production. Outreach activities will be conducted with K-12 students on topics related to adaptation and maladaptation in the face of climate change. Despite nearly a century of work on the genetics of adaptation, we know little about the contribution of non-additive genetic variation to adaptation, the extent to which adaptation exists despite maladaptive loci, and how that balance may shift with environmental change. This research will determine the genetic basis of heterosis (hybrid vigor) and heterosis-by-environment interactions for fitness, quantify the role of epistasis in adaptive differentiation, and determine the extent to which antagonistic loci contribute to transgressive segregation in crosses between locally-adapted populations. Foundational work mapping the genetic basis of long-term fitness of two ecotypes of Arabidopsis thaliana from Italy and Sweden at the native sites implicated a complex genetic basis, including epistasis, a mixture of adaptive and maladaptive alleles, and transgressive segregation for fitness in Sweden. Dominance contributes to heterosis in a cross between these ecotypes, and limited genetic variation and high heterosis characterize northern populations. The research will leverage a panel of Near Isogenic Lines (NILs) to produce homozygous, heterozygous, and combinatorial introgression segments. To investigate heterosis, epistasis, and additive complementation for fitness, fitness components of these lines will be assayed in growth chambers programmed to simulate the native environments, designed and optimized with over a decade of site level climate and fitness data. Training will be provided for a graduate and undergraduate student who will also participate in K-12 outreach activities.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.