CAREER: Backyard Evolution across a Seasonal Metapopulation in Drosophila

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。这个项目将进一步加深我们对进化是如何发生的理解，当环境在空间和时间上发生变化时，这可以推动快速适应。生活在温带栖息地的果蝇（Drosophila）是理解波动选择适应的首要系统。本项目将探索生活在果园腐烂果实和栖息在堆肥堆中的各种果蝇的自然选择，并回答以下问题：(1)这些种群是否适应这种环境变化？(2)对时间变化的快速适应是否保持了种群中的遗传变异？(3)冬季导致的死亡对季节适应有何影响？该项目将支持一项公民科学项目，在弗吉尼亚州的整个生长季节对果蝇进行取样。这些样本将用于DNA测序，并将被添加到世界上最大的苍蝇遗传变异数据库中，该数据库包含数十年来从多个大陆采样的序列。该项目还将支持研究密集型教育管道的发展，包括基于课程的本科研究，重组弗吉尼亚大学的遗传学课程，并将促进与当地社区学院的合作。研究人员将在多个果蝇物种的全基因组范围内检查等位基因频率模式，以研究适应性进化变化对选择压力的季节性波动的反应。这项工作将首先评估季节性适应是否是果蝇种群的普遍特征，通过对7年多来在生长季节的多个时间点收集的6种果蝇进行汇总重新测序。将对合并的重测序数据进行分析，以评估等位基因频率随时间的变化，并确定季节性变化选择的目标。接下来，这项工作将测试时间波动选择是否因栖息地类型（堆肥堆与果园）而异，以及苍蝇是否在当地适应任何一种栖息地类型。为了进一步研究当地对堆肥桩或果园的适应动态，该项目将对来自两种果蝇（黑腹果蝇和拟蝇）的个体基因组进行重新测序。这些数据将用于识别在不同栖息地之间差异很大的基因组区域。基因组分析将与这两个物种的广泛表型相结合，以检验关于生境类型之间表型分化的假设。最后，本研究将重点研究果蝇的越冬动力学，并将测试越冬瓶颈是否会显著影响遗传漂变导致的等位基因频率。这些分析将与室外实验中生态系统相结合，以复制由于季节性和越冬引起的漂移而产生的适应性进化变化。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。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).This project will further our understanding of how evolution happens when the environment varies in space and time, which can drive rapid adaptation. Fruit fly species (Drosophila) living in temperate habitats are premier systems to understand adaptation to fluctuating selection. This project will explore natural selection in various fruit fly species living in rotting fruit in orchards and inhabiting compost piles, and answer the following questions: (1) Do these populations adapt to this environmental variation? (2) Does rapid adaptation to variation in time maintain genetic variation in populations? (3) What are the consequences of winter-driven mortality on seasonal adaptation? This project will support a Citizen Science effort to sample fruit flies across the growing season in the state of Virginia. These samples will be used for DNA sequencing and will be added to the largest data repository of fly genetic variation in the world containing sequences from multiple continents sampled over decades. This project will also support the development of a research-intensive educational pipeline that incorporates course-based undergraduate research, restructuring of the genetics curriculum at the University of Virginia, and will facilitate collaborations with a local community college.The researchers will examine patterns of allele frequency genome-wide in multiple Drosophila species in order to study adaptive evolutionary change in response to seasonal fluctuations in selection pressure. This work will first assess if seasonal adaptation is a general feature of drosophilid populations by performing pooled re-sequencing of six drosophilid species collected at multiple points in the growing season over seven years. Pooled re-sequencing data will be analyzed to assess allele frequency change through time, and to identify targets of seasonally varying selection. Next, this work will test if temporally fluctuating selection varies across habitat type (compost piles vs. orchard) and whether flies are locally adapted to either habitat type. To further examine the dynamics of local adaptation to either compost piles or orchards, this project will re-sequence genomes of individual flies from two species, D. melanogaster and D. simulans. These data will be used to identify genomic regions that are strongly differentiated between habitats. Genomic analysis will be coupled with extensive phenotyping of these two species to test hypotheses about phenotypic differentiation between habitat types. Lastly, this work will focus on studying the overwintering dynamics of drosophilid flies and will test whether overwintering bottlenecks significantly affect allele frequencies due to genetic drift. These analyses will be combined with outdoor experimental mesocosms to replicate adaptive evolutionary change due to seasonality as well as drift due to overwintering.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.