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多样化和动态的环境条件下生存、移动和繁殖。这个项目调查了这些策略的交集，以及它们如何促进蓝蟹和一种致病性病毒在北美和南美大西洋沿岸的持久性。这种蟹-病毒系统的广泛分布使得它对研究宿主-病原体相互作用很有用。蓝蟹可以减少它们的活动水平，并在寒冷的气候下诱导冬季休眠，但目前尚不清楚这是如何改变病原体的进展和传播的。相反，热带蓝蟹全年的生长和繁殖可能被较高的病原体丰度和活性所抵消。该项目将结合实地和实验室研究，揭示螃蟹的生活史和病原体动力学是如何相互作用的，并在它们的极端范围内适应。基因测序、螃蟹运动跟踪和海洋学模型将用于了解螃蟹疾病在温带和热带纬度上的动态变化。蓝蟹是一种生态和经济上都很重要的物种，该项目产生的知识将有助于提供管理指导，以支持可持续渔业。将通过伙伴关系和讲习班向商业和手工采集者传播避免和限制疾病的最佳做法。来自弱势群体的当地高中生和本科生将参与各种正式和非正式的教育项目。公众外展将通过与谢德水族馆的博物馆合作来实施，并将包括培训一名科学传播实习生。该合作项目将结合实地和实验室实验、种群基因组学和生物物理建模，探索纬度驱动的生活史变化和海洋连通性对蓝蟹、Callinectes sapidus和致病性病毒CsRV1组成的跨半球病理系统的影响。将通过在高纬度和低纬度之间移植的螃蟹进行病毒攻毒实验，研究来自热带和温带地区的CsRV1病毒的毒力及其越冬的影响。感染和毒力对螃蟹运动的影响将通过健康螃蟹和受感染螃蟹的实验室跑道实验以及在温带和热带地区使用声学标记的螃蟹进行实地调查。种群遗传学研究使用数千个螃蟹全基因组RAD测序标记和病毒全基因组测序，将确定螃蟹和病毒种群在其分布范围内的遗传连通性，并将调查蓝蟹和病毒基因组中可能的纬度、海景和生活史驱动的变化。这两个种群基因组数据集预计将提供不同的推断和连接尺度，因为CsRV1病毒基因型仅在幼虫后螃蟹之间传播，而蓝蟹基因型也会在潜在的远距离分散幼虫阶段传播。最后，综合生物物理模型将通过十年的模拟，在新英格兰和阿根廷之间的广阔栖息地中，研究成虫和幼虫扩散对螃蟹种群结构和病原体的相对贡献。开放源代码的拉格朗日随机模型将用于估计远洋幼虫的运输，空间显式偏相关随机游动模型将用于估计成虫的运动。模型将根据实验得出的运动和行为数据，以及已发表文献中有关螃蟹幼虫和成虫行为和越冬时间的信息。在纬度和病毒感染影响螃蟹行为的一系列情景下，将对基于生物物理模型的连通性预测和基于遗传估计的连通性进行统计比较。这些分析将促进我们对形成蓝蟹CsRV1病理系统动力学的物理、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.