Environmental genomics approaches for the study of multiple stressors in freshwater ecosystems

目前对水生生境施加的人为压力（金属负荷增加、营养物浓度高、酸度增加、入侵物种的加速引入）可能产生极端的环境条件，从而改变所支持的群落，损害这些生态系统的功能。由于压力源之间的相互作用和生物体本身之间的相互作用以及压力后复杂的生态和进化动态，评估多重压力对水生生态系统的影响特别具有挑战性。拟议的工作的长期研究目标是推进新的，综合的方法在水生态系统中的多重压力的研究。 我建议使用实验进化（突变积累和围隔实验）和基因组学方法（转录组学，种群遗传学和metabarcoding）以及水蚤作为模式生物的组合，以评估水生生物群落对环境压力的反应。通过使用一个长期的突变积累实验，我们计划检查全球转录发散模式的突变线下传播的最小选择和选择下传播的分离株。这种方法将使我们能够深入了解塑造基因表达的进化力量。我们将探讨环境压力（重金属）改变突变率以及全球转录模式的程度。通过使用一个大型的围隔实验，加上人口基因组学和metabarcoding的方法，我们将评估如何在施加的环境变化的遗传多样性和社区组成的变化。我们将探讨在群体水平上的遗传变化之前，社区组成的重大变化。此外，围隔实验将使我们能够识别对压力适应性反应重要的基因。这些研究将共同提供前所未有的见解，以了解暴露于压力和1）对基因组稳定性的长期影响，2）全球转录模式，3）遗传多样性和社区组成的变化，4）快速反应能力，最终5）自然种群的长期健康之间的复杂联系。 这种实验进化和环境基因组学的独特结合将使我们的研究小组能够以以前无法达到的细节，控制和复制水平来研究多种压力对水生生态系统结构和功能属性的影响。拟议的研究还将使我们能够开发和测试新的生态基因组方法，用于研究多种压力源。拟议的项目提供了一个很好的机会，在研究生和本科层次的多学科和协作培训。

The anthropogenic pressures currently applied to aquatic habitats (increased metal loads, high concentrations of nutrients, increased acidity, accelerated introduction of invasive species) can generate extreme environmental conditions that can alter the supported communities and compromise the function of these ecosystems. Evaluating the impact of multiple stressors on aquatic ecosystems is particularly challenging due to the interactions amongst sources of stress and amongst the organisms themselves as well as the complex ecological and evolutionary dynamics that follow after stress. The long-term research objective of the proposed work is to advance new, integrative approaches for the study of multiple stressors in aquatic ecosystems. I propose to use a combination of experimental evolution (mutation accumulation and mesocosm experiments) and genomic approaches (transcriptomics, population genetics and metabarcoding) as well as Daphnia as a model organism to evaluate the responses of aquatic communities to environmental stressors. By using a long-term mutation accumulation experiment we plan to examine the global transcritional divergence patterns in mutation lines propagated under minimal selection and in isolates propagated under selection. This approach will allow us to provide insights into the evolutionary forces that shape gene expression. We will explore the extent to which environmental stressors (heavy metals) alter the mutation rate as well as the global transcriptional pattern. By using a large mesocosm experiment coupled with population genomics and metabarcoding approaches we will evaluate how genetic diversity and community composition changes during imposed environmental changes. We will explore the genetic changes at the population level that precede major changes to community composition. Moreover the mesocosm experiment will allow us to identify the genes important for adaptive responses to stressors. Jointly, these studies will provide unprecedented insights into the complex linkages between exposure to stressors and 1) the long-term effects on genome stability, 2) the global transcriptional pattern, 3) the changes in genetic diversity and community composition, 4) the capacity for rapid response, and ultimately 5) the long-term health of natural populations. This unique combination of experimental evolution and environmental genomics will allow our research group to investigate the ramifications of multiple stressors on the structural and functional attributes of aquatic ecosystems at a previously unattainable level of detail, control and replication. The proposed studies will also allow us to develop and test new ecological genomic approaches for the study of multiple stressors. The proposed projects provide an excellent opportunity for multidisciplinary and collaborative training at both graduate and undergraduate levels.