RII Track-4: Mechanisms underlying transgenerational inheritance of the stress phenotype

今天，世界上3%的土地覆盖被认为是城市。到2050年，这一数字预计将增加到5%。城市化是栖息地变化的最重要形式之一，通过局部灭绝过程导致生物多样性丧失。未来十年，城市扩张预计将影响25%的濒危物种。该项目的总体目标是研究一些动物如何能够在城市环境中茁壮成长，而另一些动物则不能，特别关注一些鸟类的自然应激反应如何使它们对光线、噪音和污染等因素做出反应。这种压力反应在生活在城市和农村地区的个体之间是不同的。该项目将通过研究生活在城市和城市环境中的麻雀来确定压力反应是否遗传。全球正在努力建设更加环保的城市，这可能会减少居住在人口稠密地区的人们的压力水平。关于个人如何适应城市生活的基本知识可以指导这种策略。PI将访问普林斯顿大学的一个实验室，学习这个项目所需的基因技术。通过与普林斯顿大学的合作，提高她在现代分子遗传学方面的能力，不仅将建立一个重要的新合作，而且将对她在内华达大学里诺分校的职业发展做出重大贡献。此外，还计划开展一些外联活动，例如公民科学家的参与，他们将通过收集城市巢箱研究的数据来了解研究过程。城市化影响着全世界的生物系统。城市和农村人口之间的表型差异表明，一些人已经适应了城市生活，而另一些人则流离失所。促进适应的一个关键特征是动物对压力的反应程度。这种应激反应具有遗传成分，并表现出个体内的可塑性。然而，这种变化背后的机制以及它们是否可能对不同环境的适应负责尚不清楚。指导这项工作的首要假设是表观遗传机制，特别是DNA甲基化，负责改变个体？对环境压力的应激反应。DNA甲基化的变化是解释生物体如何适应城市环境的主要候选者。利用来自城市化栖息地梯度的家麻雀（Passer domesticus）， PI将首先检查特定候选基因DNA甲基化模式的城乡差异，并将这些模式与应激反应联系起来。为了揭示应激反应的差异是由于遗传适应还是表型可塑性，一项前所未有的交叉培养田间实验将与多代筛选应激表型和甲基化模式相结合。这个实验解开了基因、表达和环境影响对应激反应变异的贡献。通过将城市生态学、内分泌学和表观遗传学领域联系起来，该项目将率先深入了解生理反应背后的表观遗传变异。了解所观察到的表型差异背后的机制将使我们能够更好地评估动物适应城市生活的潜力，从而评估城市化对野生种群的影响。在一个日益受到城市化压力的世界中，所获得的信息正变得至关重要。

Non-technical DescriptionToday, 3% of the world's total land cover is considered urban. By 2050, this number is expected to increase to 5%. Urbanization is one of the most significant forms of habitat change, resulting in biodiversity loss through local extinction processes. Urban expansion is expected to impact 25% of all endangered species in the next decade. The overall objective of this project is to investigate how some animals are able to thrive in urban environments while others are not, with a particular focus on how the natural stress response of some birds allows them to respond to factors such as light, noise, and pollution. This stress response differs between individuals that live in urban versus rural areas. This project will determine whether the stress response is genetically inherited by studying house sparrows living in a range of urban and urban settings. There is increasing global effort to build more environmentally-friendly cities, which may reduce stress levels of humans living in densely populated areas. Basic knowledge on how individuals adapt to city life can guide such strategies. The PI will visit a laboratory at Princeton University to learn the genetic techniques required for this project. Increasing her competence in modern molecular genetics through cooperation with Princeton will both establish an important new collaboration, and will significantly contribute to development of her career at the University of Nevada at Reno. In addition, a number of outreach activities are planned, such as the involvement of citizen scientists who will learn about the research process through collection of data from urban nest box studies.Technical DescriptionUrbanization affects biological systems worldwide. Phenotypic differences between urban and rural populations demonstrate that some individuals have adapted to city life while others are displaced. A key trait facilitating adaptation is the degree to which animals respond to stress. This stress response has a heritable component and exhibits intra-individual plasticity. However, the mechanisms behind this variability and whether they might be responsible for adaptation to different environments are not known. The overarching hypothesis guiding this work is that an epigenetic mechanism, specifically DNA methylation, is responsible for modifying an individual?s stress response to environmental pressures. Variation in DNA methylation is a prime candidate to explain how organisms adapt to urban environments. Using house sparrows (Passer domesticus) from a gradient of urbanized habitats, the PI will first examine urban-rural differences in DNA methylation patterns at specific candidate genes and relate these patterns to the stress response. To unravel if differences in the stress response are due to heritable adaptation or phenotypic plasticity, an unprecedented cross-fostering field experiment will be integrated with multi-generational screening of the stress phenotype and methylation patterns. This experiment disentangles the contribution of genes, expression, and environmental effects across generations to variation in the stress response. By linking the fields of urban ecology, endocrinology, and epigenetics, this project will pioneer insights into the epigenetic variation underlying a physiological response. Knowledge of the mechanisms behind observed phenotypic differences will enable us to better assess the potential for adaptation of animals to city life, and thereby the impact of urbanization on wild populations. The information acquired is becoming essential in a world that is increasingly experiencing the stress of urbanization.