How do multiple coastal stressors structure the genomic diversity of marine populations?

从长期的全球海洋变化到局部的沿海酸化，海洋物种面临着跨越多个时间和空间尺度的一系列复杂的应激因素。多个应激源的累积和同时影响仍然相对未知，需要研究它们在所有生命阶段的协同影响。沿海环境中的两个常见压力来源是低氧和海岸酸化。低氧和海岸酸化与呼吸和光合作用的每日循环有关，即使在原始的海湾和河口也是如此。沿海水域还受到降雨和风暴事件驱动的天然和人工淡水径流脉冲的影响。淡水脉动可能会导致短期的低盐度条件，这是另一个压力源，预计会随着气候变化而恶化。对于许多海洋物种来说，幼虫阶段是唯一的迁徙和遗传交换手段，幼虫在浅海水域可能会遇到缺氧、海岸酸化和低盐度应激源。此外，早期青少年可能会遇到所有这三种应激源的较长时间。早期生活史阶段与沿海应激源的反复和组合相互作用，有可能导致幼虫/幼虫死亡率增加或移走耐力较差的幼虫。这种不同死亡率的后果正在通过实验室多应激源暴露实验在东部牡蛎中进行研究，并在野外通过对自然种群的基因组调查进行研究。通过结合基因组和环境数据来分析遗传选择的模式，以阐明多种应激源是如何塑造海洋种群的。更广泛的影响包括博士后、研究生和本科生的培训机会以及社会影响。这项研究的结果是预测牡蛎礁如何适应长期气候变化和人类人口增长的关键。计划举行一次研讨会，将科学家和更广泛的社区成员聚集在一起，讨论牡蛎礁的保护和恢复以及可持续水产养殖。更好地了解幼体和幼体对应激源的生理限制有助于牡蛎孵化场优化选择和筛选适合健壮幼体和幼体的亲本。主要目标是表征低氧(DO)、海岸酸化(CA)和低盐度事件(LS)如何影响海洋无脊椎动物的种群连通性和微进化过程。随着幼虫的生长和发育，它们可能能够耐受短期的环境应激源，但长期暴露在白天的DO/CA循环和LS事件中可能会降低随后的存活，特别是在幼虫中。幼虫和幼虫与多种应激源的相互作用有可能通过简单地不允许迁徙交换来扰乱基因流动，或者作为一种选择性力量，通过基因-环境相互作用来构建种群。该项目使用实验和海景基因组学相结合的方法来研究多重应激源是如何塑造观察到的基因组多样性的。第一阶段是确定幼虫和幼虫的基因类型和表型如何在不同的发育时间点对多种应激源做出反应。实验包括两个短期暴露于DO/CA和LS因子组合的幼虫，以及长期暴露于DO/CA昼夜循环和LS因子组合的幼虫。在实验暴露期间表达的基因的编码区正在使用一种具有成本效益的外显子组捕获方法进行测序。第二阶段是确定自然和人为力量在牡蛎种群进化中的作用，方法是测试不同的选择制度是否在不同的生活史阶段存在差异和相互作用，以及中性和抗性基因型的频率是否与环境条件相关。对来自几个城市化河口的多个地点的成年种群基因组的调查正在基于一组基因组标记生成海景基因组框架，其中包括早期生命历史中选择的潜在位置。这些数据正在与环境数据结合起来，以阐明促成种群结构和地方遗传多样性的各种因素的组合。结果表明，中性和假定有选择性的基因座上的成人基因频率与早期幼虫、晚期幼虫和幼体早期暴露于应激源的等位基因频率的变化有关。这项研究正在揭开选择、迁徙和漂移对海洋遗传多样性的复杂相互作用，以机械地理解沿海应激源的基因组后果及其对幼虫的相互作用。该项目由生物海洋学和综合组织系统联合资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Marine species face a complex suite of stressors that span multiple temporal and spatial scales from long-term global ocean change to localized episodes of coastal acidification. The cumulative and concurrent impacts of multiple stressors remain relatively unknown and requires investigating their synergistic impacts across all life stages. Two common stressors in coastal environments are hypoxia, or low dissolved oxygen, and coastal acidification. Hypoxia and coastal acidification are linked to daily cycles of respiration and photosynthesis, even in pristine bays and estuaries. Coastal waters are also affected by pulses of natural and artificial freshwater runoff driven by rainfall and storm events. Pulses of freshwater can cause short-term, low salinity conditions, another stressor, that are expected to worsen with climate change. For many marine species, larval stages are the only means of migration and genetic exchange, and larvae are likely encountering hypoxia, coastal acidification, and low salinity stressors while they are in shallow coastal waters. Additionally, early juveniles may encounter extended periods of all three stressors. The interaction of early life-history stages with repeated and combinations of coastal stressors has the potential to result in an increase of larval/juvenile mortality or the removal of less tolerant larvae. The consequences of this differential mortality are being investigated in the eastern oyster using laboratory multi-stressor exposure experiments and in the field through genomic surveys of natural populations. Patterns of genetic selection are being analyzed by combining genomic and environmental data to elucidate how multiple stressors are shaping marine populations. Broader impacts include training opportunities for a post-doctoral fellow, graduate and undergraduate students and societal impacts. Results from the study are key to predicting how oyster reefs will adapt to long-term climate change and human population growth. A symposium is planned to bring scientists and members of the broader community together to discuss conservation and restoration of oyster reefs and sustainable aquaculture. A better understanding the physiological limits of larvae and juveniles to stressors is contributing to new strategies for oyster hatcheries to optimize selection and screening of brood stock for robust larvae and juveniles.The broad goal is to characterize how hypoxia (DO), coastal acidification (CA), and low salinity events (LS) shape population connectivity and microevolutionary processes of marine invertebrates. As larvae grow and develop, they may be able to tolerate short-term exposures to environmental stressors, but prolonged exposure to diurnal DO/CA cycling and LS events may reduce subsequent survival, especially in juveniles. Larval and juvenile interactions with multiple stressors have the potential to either disrupt gene flow by simply not allowing migrant exchange or to act as a selective force, structuring populations through genotype-environment interactions. This project uses a coupled experimental and seascape genomics approach to investigate how multiple stressors are shaping observed genomic diversity. Phase 1 is determining how larval and juvenile genotypes and phenotypes respond to multiple stressors across different developmental time points. Experiments include two larval short-term exposures to factorial combinations of DO/CA and LS, and a long-term juvenile exposure to factorial combinations of DO/CA diurnal cycling and LS. The coding regions of genes expressed during experimental exposures are being sequenced using a cost-effective exome capture method. Phase 2 is determining the role of natural and anthropogenic forces shaping the evolution of oyster populations by testing if selective regimes differ and interact across life-history stages and if the frequencies of both neutral and resistant genotypes correlate with environmental conditions. Surveys of the genomes of adult populations across multiple localities from several urbanized estuaries are generating a seascape genomic framework based on a panel of genomic markers, including potential loci under selection during early-life history. These data are being integrated with environmental data to elucidate the mix of factors that contribute to population structure and local genetic diversity. Results are linking adult genotype frequencies at both neutral and putatively selective loci to changes in allele frequencies in response to early larval, late larval, and early juvenile exposure to stressors. The research is unraveling the complex interaction of selection, migration, and drift on marine genetic diversity for a mechanistic understanding of the genomic consequences of coastal stressor and their interaction on larvae.This project is jointly funded by Biological Oceanography and Integrative Organismal Systems.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.