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

了解生物体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，这样的知识可以改进作物育种，并可以提高对本土和农艺物种对气候变化反应的预测。目前关于适应遗传学的知识大多局限于遗传变异的一个子集，其中一个基因的不同副本(等位基因)对生存和繁殖的影响是相加的，可以简单地总结在一起。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。其中一个例子被称为杂交活力，通常发生在不同品系的植物交配时，产生的杂交后代比亲本品系的存活率更高，种子产量也更高。这项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学生一起开展与气候变化中的适应和适应不良有关的主题的外联活动。尽管对适应的遗传学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、适应在多大程度上存在、以及这种平衡如何随着环境变化而变化知之甚少。这项研究将确定杂种优势(杂交优势)的遗传基础和适应能力的环境杂种优势交互作用，量化上位性在适应分化中的作用，并确定拮抗基因座对本地适应群体之间杂交的超亲分离的贡献程度。对来自意大利和瑞典的两个生态型拟南芥的长期适合性的遗传基础进行的基础性工作表明，瑞典存在复杂的遗传基础，包括上位性、适应性和非适应性等位基因的混合以及适合性的超亲分离。在这些生态型之间的杂交中，显性贡献了杂种优势，而有限的遗传变异和高度的杂种优势是北方群体的特征。这项研究将利用一组近等基因系(NILs)来产生纯合、杂合和组合导入片段。为了研究杂种优势、上位性和加性互补对适合度的影响，这些品系的适合度成分将在模拟自然环境的生长室中进行分析，这些生长室的设计和优化使用了十多年的立地气候和适合度数据。该奖项反映了NSF的法定使命，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，被认为是值得支持的。

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.