Collaborative research: Variation in life history and connectivity as drivers of pathogen-host dynamics and genetic structure in a trans-hemispheric pathosystem

海洋无脊椎动物使用一系列策略在不同和动态的环境条件下生存、移动和繁殖。该项目调查这些战略的交集以及它们如何促进蓝蟹和一种致病病毒在北美和南美洲大西洋沿岸的持续存在。这种螃蟹病毒系统的广泛分布使其成为研究宿主-病原体相互作用的有用工具。蓝蟹可以降低它们的活动水平，并在较冷的气候中诱导冬季休眠，但目前尚不清楚这如何改变病原体的进展和传播。相反，热带蓝蟹全年的生长和繁殖可能会被更高的病原体丰度和活性所抵消。这个项目将使用现场和实验室研究相结合的方法来揭示螃蟹的生活史和病原体动态如何在其范围的极端情况下相互作用和适应。将使用基因测序、螃蟹运动跟踪和海洋模型来了解螃蟹疾病动态在温带和热带纬度之间的差异。蓝蟹是一种具有重要生态和经济价值的物种，该项目所产生的知识将有助于为支持可持续渔业提供管理指导。将通过伙伴关系和讲习班向商业和手工收割机传播避免和限制疾病的最佳做法。来自代表性不足群体的当地高中生和本科生将通过各种正式和非正式的教育计划参与进来。将通过与Shedd水族馆的博物馆伙伴关系实施公共宣传，并将包括培训科学交流互联网。这一合作项目将结合经验现场和实验室实验、种群基因组学和生物物理模型，以探索由纬度驱动的生活史和海洋连通性变化对由蓝蟹Callinectes Sapidus和致病病毒CsRV1组成的跨半球病理系统的影响。来自热带和温带的CsRV1病毒的毒力以及越冬的影响将通过在高纬度和低纬度之间移植的螃蟹的实验病毒挑战来研究。感染和毒力对螃蟹运动的影响将在健康和受感染的螃蟹的实验室跑道实验中进行调查，并在温带和热带地区部署声学标记的螃蟹的野外试验中进行。使用数千个针对螃蟹的全基因组RAD测序标记和针对病毒的全基因组测序进行的种群遗传学研究将确定整个范围内螃蟹和病毒种群的遗传连通性，并将调查可能由纬度、海景和生活史驱动的蓝蟹和病毒基因组的变化。预计这两个种群基因组数据集将提供不同的推断和连接性的规模，因为CsRV1病毒基因型仅在幼蟹之间传播，而蓝蟹基因型也通过潜在的远程弥散幼虫阶段传播。最后，通过十年的模拟，综合生物物理模型将被用来调查成虫和幼虫的扩散对新英格兰和阿根廷之间大片栖息地的螃蟹和病原体种群结构的相对贡献。一个开源的拉格朗日随机模型将估计浮游幼虫的运输，而空间显式的有偏相关的随机行走模型将估计成虫的运动。模型将通过实验得出的运动和行为数据，以及出版的文献中有关螃蟹幼虫和成虫行为和越冬持续时间的信息来提供信息。在螃蟹行为受纬度和病毒感染影响的一系列情景下，将在基于生物物理模型的连通性预测和遗传连通性估计之间进行统计比较。这些分析将促进我们对形成蓝蟹CsRV1病理系统动态的物理、环境和生物因素的理解。

Marine invertebrates use an array of strategies to survive, move, and reproduce across diverse and dynamic environmental conditions. This project investigates the intersection of these strategies and how they facilitate the persistence of blue crabs and a pathogenic virus along the Atlantic coast of North and South America. The widespread distribution of this crab-virus system makes it useful for investigating host-pathogen interactions. Blue crabs can reduce their activity level and induce winter dormancy in colder climates, but it is unclear how this alters progression and transmission of the pathogen. Conversely, year-round growth and reproduction of tropical blue crabs may be offset by higher pathogen abundance and activity. This project will use a combination of field and laboratory studies to reveal how crab life history and pathogen dynamics interact and adapt at the extremes of their range. Genetic sequencing, crab movement tracking and oceanographic models will be used to understand how crab-disease dynamics vary across temperate and tropical latitudes. The blue crab is an ecologically and economically important species and knowledge generated in this project will help provide management guidance to support sustainable fisheries. Best practices to avoid and limit disease will be communicated to commercial and artisanal harvesters through partnerships and workshops. Local high school and undergraduate students from underrepresented groups will be engaged through a variety of formal and informal educational programs. Public outreach will be implemented through a museum partnership with the Shedd Aquarium and will include the training of a science communication intern.This collaborative project will combine empirical field and laboratory experiments, population genomics, and biophysical modeling to explore the consequences of latitude-driven changes in life history and oceanic connectivity on a trans-hemispheric pathosystem comprised of the blue crab, Callinectes sapidus, and the pathogenic virus, CsRV1. The virulence of the CsRV1 virus from tropical and temperate latitudes and the impact of overwintering will be studied by experimental virus challenges of crabs transplanted between high and low latitudes. The impact of infection and virulence on crab movement will be investigated in laboratory raceway experiments of healthy and infected crabs and in the field with acoustically tagged crabs deployed in temperate and tropical locations. Population genetic studies using thousands of genome-wide RAD sequencing markers for crabs and whole-genome sequencing for the virus will define genetic connectivity of crab and virus populations across their range, and will investigate the possible latitudinal, seascape, and life history-driven changes in blue crab and virus genomes. The two population genomic data sets are expected to provide different inferences and scales of connectivity because CsRV1 virus genotypes are transmitted only among post-larval crabs while blue crab genotypes also move by a potentially long-range dispersive larval stage. Finally, integrated biophysical models will be used to investigate the relative contributions of adult and larval dispersal on the population structure of the crab and the pathogen across a broad swath of habitat between New England and Argentina with a decade of simulations. An open-source Lagrangian stochastic model will estimate pelagic larval transport, and spatially explicit biased-correlated random walk models will estimate adult movement. Models will be informed by experimentally-derived movement and behavior data, as well as information on crab larval and adult behavior and overwintering duration available in the published literature. Under a series of scenarios in which crab behavior is affected by latitude and virus infection, statistical comparisons will be made between biophysical model-based predictions of connectivity and genetic estimates of connectivity. These analyses will advance our understanding of the physical, environmental, and biological factors that shape the dynamics of the blue crab CsRV1 pathosystem.