Tracking adaptive evolution in real time in an invasive fruit fly

项目总结 入侵物种可能携带疾病，摧毁粮食作物，威胁生物多样性， 在新的环境中取得成功，但使其传播的生物学机制仍然难以捉摸。一些人 入侵物种显示出快速适应新栖息地的迹象，但很少有研究捕捉到入侵后的情况 实时自适应。此外，同时在多个栖息地定居的入侵物种提供了 有机会研究进化论是否可预测这一长期存在的问题。要了解有多快 和可预见的生物体适应新的殖民环境，重复的详细的基因组研究 初期的入侵是必要的。在这项研究中，我们将从基因和表型上描述诺斯 美国种群的非洲无花果苍蝇，测试当地适应和平行 在它正在进行的入侵中进化。这种易驯服的模型生物到达北美不到两年 几十年前，并迅速蔓延。我们的数据表明，每年冬天，它都会在当地从温带栖息地灭绝 并在每年春天重新殖民这些地区。我们的中心假设是印度斑潜蝇经历了可预测的 殖民后适应跨越多个地点和年份，导致等位基因重复变化 频率和生态相关的表型。为了验证这一假设，我们将收集、排序和 来自北美东海岸和弗吉尼亚州两个果园的表型分离株 好几年了。在目标1中，我们将通过以下方式量化北美人群的遗传和表型变异 生成沿纬度梯度收集的种群的集合排序以测试临床变化 两个抽样年的多态现象。我们还将在不同纬度收集表型线进行测试 形态、生活史和抗逆性表型的克隆差异。反复的阵发性和 表型分化将为快速适应当地环境提供证据。在目标2中，我们将 对来自两个地理位置不同的弗吉尼亚州果园的苍蝇进行采样和排序，在三个生长季节到 检测入侵后可预见的变化的等位基因和表型。这些实验将使我们能够 确定入侵后适应的基因组目标，并量化进化的可预测性。在《目标3》中， 我们将描述最近北美苍蝇选择性扫描的假定目标：600kb的单倍型 这在弗吉尼亚州很常见，在佛罗里达州是中频，在非洲没有。我们将产生异种繁殖 固定交替等位基因的群体，并执行RNAseq以测试相关差异基因表达 具有交替的单倍型。表型实验将探索这一扫描的潜在功能靶点， 使我们能够剖析选择的基因组信号的生物功能。总的来说，这些实验 将采取多管齐下的方法，实时测试入侵后的适应和并行进化。这 研究将为理解对新环境的快速适应和预测提供一个框架 未来入侵物种的进化轨迹，这可能导致控制其传播的解决方案。

PROJECT SUMMARY Invasive species, which can carry diseases, decimate food crops and threaten biodiversity, are immensely successful in new environments, but the biological mechanisms that enable their spread remain elusive. Some invasive species show signs of rapid adaptation to new habitats, but few studies have captured post-invasion adaptation in real time. Additionally, invasive species colonizing multiple habitats simultaneously offer the opportunity to study the longstanding question of whether evolution is predictable. To understand how quickly and predictably organisms adapt to newly colonized environments, detailed genomic studies of repeated incipient invasions are necessary. In this study, we will genetically and phenotypically characterize North American populations of the African Fig Fly, Zaprionus indianus, to test for local adaptation and parallel evolution in its ongoing invasion. This tractable model organism arrived in North America less than two decades ago and rapidly spread. Our data suggest it is locally extirpated from temperate habitats each winter and re-colonizes these locales each spring. Our central hypothesis is that Z. indianus undergoes predictable post-colonization adaptation across multiple locations and years, resulting in repeated changes in allele frequencies and ecologically relevant phenotypes. To test this hypothesis, we will collect, sequence, and phenotype isolates from along the East Coast of North America and from two focal Virginia orchards over multiple years. In Aim 1, we will quantify genetic and phenotypic variation in North American populations by generating pooled sequencing of populations collected along a latitudinal gradient to test for clinally varying polymorphisms over two sampling years. We will also phenotype lines collected at different latitudes to test for clinal differences in morphological, life-history, and stress tolerance phenotypes. Repeated clinal and phenotypic differentiation would present evidence for rapid adaptation to local environments. In Aim 2, we will sample and sequence flies from two geographically separate Virginia orchards over three growing seasons to test for alleles and phenotypes that predictably change following invasion. These experiments will allow us to identify the genomic targets of post-invasion adaptation and quantify the predictability of evolution. In Aim 3, we will characterize the putative target of a recent selective sweep in North American flies: a 600 kb haplotype that is common in Virginia, intermediate frequency in Florida, and not found in Africa. We will generate outbred populations fixed for alternate alleles and perform RNAseq to test for differential gene expression associated with alternate haplotypes. Phenotyping experiments will explore the potential functional targets of this sweep, allowing us to dissect the biological function of a genomic signal of selection. Collectively, these experiments will take a multipronged approach to test for post-invasion adaptation and parallel evolution in real time. This study will provide a framework to understanding rapid adaptation to novel environments and predicting evolutionary trajectories of future invasive species, which may lead to solutions to control their spread.