Collaborative Research: Dynamic similarity or size proportionality? Sensory ecological adaptations of Euchaeta to viscosity

协作研究：动态相似性还是大小比例？

• 批准号: 2023675
• 负责人: Jeannette Yen
• 金额: $ 54.96万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2023675&HistoricalAwards=false
• 关键词: Collaborative; Research; Dynamic; similarity; size

Small planktonic organisms like copepods live at the interface of laminar and turbulent regimes, which is a fluid environment that is not well understood. It is not turbulent, like the rumbly wake behind a ski boat. It is not predictable laminar flow, like the steady flow creeping by a smooth stone. In this transitional environment, even small changes in the viscosity of the water can impact an organism’s behavior and sensory perception in unexpected ways. Waters in the polar regions have twice the viscosity as that in the subtropics. In addition to viscosity there are thermal effects on physiology and differences in organism size. Nevertheless, pilot studies indicate that polar species are dynamically similar to the subtropical ones. This suggests their fluid-object interactions with their surrounding environment is very similar from the poles to the subtropics. The goal of this study is to measure nerve impulse conduction velocities, respiration rates, swimming and escape speeds, and muscle mass to determine whether and what metabolic compensation is occurring to maintain this dynamic similarity. The broader impacts include training early career scientists at different stages of their education to work across STEM disciplines. Eight trainees ranging from undergraduate to post-doctoral levels are working within the fields of fluid dynamics, marine biology and neurophysiology to address questions surrounding the evolution of key organisms in the ocean. By creating an educational ladder in the lab, students are learning to mentor other students as they learn the scientific method. Outreach is focused on incorporating results from this project into exhibits at the Museum of Design Atlanta, Georgia to share how planktonic organisms can become part of innovative design using solutions from nature to improve the way problems are solved. Flow regimes at intermediate Reynolds number are characterized by the transition between viscous and inertia-dominated realms. Zooplankton like copepods operate within this interface. These small organisms detect prey, predators and mates by sensing small changes in the fluid that surrounds them. However, fluid viscosity alters the fluid signals that are created and perceived by the organisms and how this affects the performance of individual copepods is poorly understood. The goal of this project is to investigate the role viscosity plays as an evolutionary force leading to adaptations in body size, volume of flow field, sensor length and neural function, swimming speeds and muscle mass. The model system for this study is a group of three species in the genus Euchaeta. The target species have evolved to live in a gradient of fluid regimes spanning temperatures from 0 to 23ºC and viscosities from 1.84 to 1 Centistokes. The species vary in length by three-fold and swim at speeds from less than 1 to over 103 millimeters per second. Nerve impulse conduction velocities, respiration rates, swimming and escape speeds, and muscle mass are being measured experimentally under a range of viscosities to elucidate underlying mechanisms of metabolic compensation involved in the maintenance of dynamic similarity from the subtropics to the poles. The focus on the congeners offers a natural experiment to examine the effects of viscosity in an organism that lives at intermediate Reynolds number where viscous forces are important.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.

像桡足类这样的小型浮游生物生活在层流和湍流状态的交界处，这是一个尚不清楚的流体环境。它并不像滑雪船后面的隆隆声那样汹涌。它不是可预测的层流，就像光滑石头上蠕动的稳定流一样。在这种过渡环境中，即使水粘度的微小变化也会以意想不到的方式影响生物体的行为和感官知觉。极地地区水域的粘度是亚热带地区水域的两倍。除了粘度之外，还有对生理学的热影响和生物体大小的差异。然而，试点研究表明，极地物种在动态上与亚热带物种相似。这表明从极地到亚热带，它们与周围环境的流体-物体相互作用非常相似。这项研究的目的是测量神经冲动传导速度、呼吸频率、游泳和逃逸速度以及肌肉质量，以确定是否以及发生什么代谢补偿来维持这种动态相似性。更广泛的影响包括培训处于不同教育阶段的早期职业科学家跨 STEM 学科开展工作。八名从本科生到博士后的学员正在流体动力学、海洋生物学和神经生理学领域工作，以解决有关海洋中关键生物体进化的问题。通过在实验室中创建教育阶梯，学生们可以在学习科学方法时指导其他学生。外展活动的重点是将该项目的成果纳入佐治亚州亚特兰大设计博物馆的展览中，以分享浮游生物如何成为创新设计的一部分，利用大自然的解决方案来改进问题的解决方式。 中间雷诺数的流动状态的特征是粘性和惯性主导领域之间的过渡。像桡足类这样的浮游动物在这个界面中运作。这些小生物通过感知周围液体的微小变化来检测猎物、捕食者和配偶。然而，流体粘度会改变生物体产生和感知的流体信号，而这如何影响个体桡足类的性能却知之甚少。该项目的目标是研究粘度作为一种进化力量所发挥的作用，从而导致身体尺寸、流场体积、传感器长度和神经功能、游泳速度和肌肉质量的适应。本研究的模型系统是真毛藻属的三个物种。目标物种已经进化到可以生活在温度范围为 0 至 23°C、粘度范围为 1.84 至 1 厘沲的流体状态梯度中。这些物种的长度相差三倍，游泳速度从每秒不到 1 毫米到超过 103 毫米不等。神经冲动传导速度、呼吸频率、游泳和逃逸速度以及肌肉质量正在一系列粘度下进行实验测量，以阐明涉及维持从亚热带到极地动态相似性的代谢补偿的基本机制。对同系物的关注提供了一个自然的实验来检查粘性对生活在中等雷诺数的生物体中的影响，其中粘性力很重要。该奖项反映了 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。