CAREER: Seasonal migration as an ecological barrier to gene flow between hybridizing species

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。该项目将利用最先进的跟踪和基因组技术，测试迁徙在维持和创造生物多样性方面的作用。来自几乎每个动物种群的个体迁徙，每年有数十亿个体迁徙数千公里。关于迁徙路线的相当大的差异已有记载，但人们不太清楚的是这种差异的潜在遗传基础以及维持物种边界甚至促进新物种多样化的后果。这项研究将利用全球无线电发射塔网络来收集斯温森画眉的迁徙路线数据，斯温森画眉是一种迁徙鸟类，具有东向和西向的迁徙亚种。与许多其他物种一样，该物种的个体每年从北美西北部的繁殖地经由中美洲和南部迁徙到智利。该项目将评估迁徙路线的基本遗传学，以及介于经典的东西方生存和维持亚种路线之间的路线的后果。许多无线电塔都是由学校托管的。因此，这个项目的研究主题和基础设施也将被用作美洲各地小学、中学和本科生的教学资源的灵感来源。将为教师设计侧重于迁徙和进化的教育模块，以英语和西班牙语提供，并通过画眉鸟的迁徙路线向全球学生提供。这些单元将结合“科学的本质”的教学方法，突出代表不足的群体在STEM研究中的作用，同时将国际协调作为保护迁徙物种的关键。移民对物种形成的重要性是近30年前提出的，但受到的关注要少得多。许多候鸟彼此交配繁殖，但使用不同的迁徙路线。这些路线在很大程度上是由基因决定的，往往涉及绕过巨大的地理障碍。因此，据预测，这些系统中的杂交种将采取中间路线，使它们越过这些障碍，降低它们的适合度和物种之间的基因流动。这个项目将测试迁徙在物种形成中的作用。具体地说，用于跟踪鸟类的最新基础设施和开发用于在低覆盖率下对数百个个体进行基因分型的基因组资源将被用于(1)比较亲本和杂交画眉的存活率，(2)识别潜在的迁徙特征的遗传变异，以及(3)测试针对杂交个体的选择是否对这些变异起作用。到目前为止，还没有对迁徙在物种形成中的作用进行直接测试，这在我们对物种形成的理解上留下了严重的差距，因为迁徙的差异在分类学上是普遍存在的，可能有助于解释为什么年轻物种对在温带地区占主导地位。迁徙也可能是外在合子后隔离障碍的一个引人注目的例子，因为杂交适合度的降低源于它们的中间行为和父母环境之间的不匹配。外在隔离被认为在物种形成中很重要，但它在自然界中的程度尚不清楚，特别是在脊椎动物中。这项工作也将涉及物种形成以外的领域，包括复杂行为和保护的遗传学。这一奖项反映了NSF的法定使命，并通过使用基金会的智力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 test the role of migration in maintaining and generating biodiversity using state-of-the-art tracking and genomic technology. Individuals from nearly every animal group migrate and billions of individuals, migrate thousands of kilometers each year. Considerable variation in migration route has been documented but what is less well understood is the underlying genetic basis for that variation and the consequences for maintaining species boundaries or even promoting diversification of new species. This research will make use of a global network of radio towers to collect data on migration routes in the Swainson’s thrush, a migratory bird with eastern- and western-migrating subspecies. Individuals of this species, like many others, migrate from breeding grounds in the northwestern North America via central America and south into Chile each year. This project will evaluate the underlying genetics of migration route and the consequences of routes intermediate between the classical eastern and western routes for survival and the maintenance of the subspecies. Many of the radio towers are hosted by schools. Thus, research themes and infrastructure from this project will also be used as inspiration for teaching resources for elementary, secondary, and undergraduate students across the Americas. Education modules focused on migration and evolution will be designed for teachers, provided in English and Spanish, and offered to students internationally across the migration routes of the thrush. These modules will integrate ‘nature of science’ pedagogy and highlight the role of under-represented groups in STEM research while featuring international coordination as key to the protection of migrating species. Migration’s importance for speciation was proposed nearly three decades ago but has received far less attention. Many migrants breed next to one another but use different migratory routes. These routes are largely genetically determined and often involve navigation around large geographic barriers. Accordingly, hybrids in these systems are predicted to take intermediate routes that bring them over these barriers, reducing their fitness and gene flow between species. This project will test migration’s role in speciation. Specifically, state of the art infrastructure for tracking birds and genomic resources developed to genotype hundreds of individuals at low coverage will be used to (1) compare survival rates of parental and hybrid thrushes, (2) identify genetic variants underlying migratory traits, and (3) test if selection against hybrids is acting on these variants. No direct test of migration’s role in speciation has been conducted to date, leaving critical gaps in our understanding of speciation, given that differences in migration are taxonomically widespread and could help explain the predominance of young species pairs in the temperate region. Migration could also be a compelling example of an extrinsic postzygotic isolating barrier, given that reductions in hybrid fitness derive from mismatches between their intermediate behavior and parental environments. Extrinsic isolation is thought to be important in speciation, but its extent in nature is unknown, especially in vertebrates. This work will reach fields beyond speciation as well, including the genetics of complex behavior and conservation.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.