OCE-PRF Track 1 (Broadening Participation): What drives population connectivity in the open sea?

随着地球气候的变化，陆地和海洋物种的种群正以三种主要方式之一做出反应：适应新环境，迁移到更有利的环境，或者灭绝。虽然对陆生物种和一些沿海海洋物种对气候变化的反应的评估已经进行了至少十年，但关于开放海洋浮游动物的数据有限。这种知识上的差距是显著的，因为浮游动物构成了开放海洋食物链的基础，而浮游动物被认为是对环境变化最敏感的海洋物种之一。本项目主要研究了栖息在热带和亚热带海域的主要洄游浮游动物——剑鳍平腹鱼（Pleuromamma xiphias）桡足类，以及环境变化对剑鳍平腹鱼种群数量的影响。研究结果对于理解开放的海洋食物网和营养循环是如何随时间变化的，以及这反过来如何影响食物链中对我们的食物资源至关重要的物种的丰度和分布，将非常重要。与这项工作相结合，该研究员将在三个关键的教育阶段指导夏威夷传统上代表性不足的学生群体：当他们最初对科学感到兴奋并了解科学在社会中的作用时（K-12），当他们决定是否将科学作为职业时（本科生），以及当他们需要强有力的指导才能在科学追求中取得成功时（研究生）。在海洋系统中，浮游生物物种被认为是环境变化的敏感指标。由于这些远洋生物的世代周期短，它们的种群往往表现出物理强迫和生物反应之间的紧密耦合。然而，浮游生物是否有能力适应迅速变化的海洋环境而进化，它们的数量和地理范围是否会减少，或者它们是否会改变它们对主要栖息地的偏好，这些问题仍然存在。为了了解浮游生物种群的适应能力，我们首先需要了解目标物种基因交换的时空尺度，并确定决定这些尺度边界的因素。该项目将利用一种远洋桡足动物（剑足Pleuromamma xiphias）的全基因组数据，结合跨时空梯度收集的多个环境变量，评估决定公海种群连通性规模的因素，并推断这些因素如何影响大西洋剑足p种群对气候变化的响应。具体而言，研究员将研究以下假设：1)生物和物理环境是塑造剑剑鱼种群结构的选择性力量；(2)北大西洋和南大西洋环流内的迁移率较高，但在各环流的极向边缘和赤道两侧的迁移率较低；3)剑蝗种群数量将不断增加，并向两极分布范围扩展，而赤道边缘的种群数量将出现瓶颈。这项工作将在夏威夷大学马诺阿分校海洋与地球科学与技术学院（SOEST）的Erica Goetze博士的指导下进行。每一项比较（基因、地点、时间点、环境变量）都将有助于深入了解远洋浮游动物的遗传结构。综合起来，它们有可能改变我们对开放海洋中种群连通性的看法，并为远洋桡足类动物在不断变化的气候中的潜在适应能力提供新的线索。

As earth's climate changes, populations of both terrestrial and marine species are responding in one of three major ways: by adapting to new environments, by moving to a more favorable environment, or by perishing. While evaluating these responses to climate change has been ongoing for terrestrial species and some coastal marine species for at least a decade, the data on open ocean zooplankton has been limited. This gap in knowledge is significant, as zooplankton form the base of the open ocean food chain, and zooplankton are hypothesized to be some of the most sensitive marine species to environmental change. This project focuses on the copepod Pleuromamma xiphias, a dominant migratory zooplankton in tropical and subtropical waters worldwide, and how populations of P. xiphias are affected by environmental change. Results will be important for understanding how open ocean food webs and nutrient cycles are changing with time, and how this in turn may affect the abundance and distribution of species higher in the food chain that are vital to our food resources. In conjunction with this work, the fellow will mentor traditionally underrepresented groups of students in Hawai'i at three critical educational levels: when they are initially becoming excited about science and learning about the role of science in society (K-12), when they are deciding whether or not to pursue science as a career (undergraduate students), and when they require strong mentorship to succeed in their scientific pursuits (graduate students). In marine systems, planktonic species have been proposed as sensitive indicators of environmental change. With short generation times, populations of these pelagic organisms often show tight coupling between physical forcing and biological response. However, the question remains whether plankton have the capacity to adaptively evolve with respect to rapidly changing ocean regimes, whether they will decrease in population abundance and geographic extent, or whether they will alter their primary habitat preferences. To understand the adaptive capacity of plankton populations, we first need to understand the spatiotemporal scale of gene exchange for the species of interest, and identify the factors that determine the boundaries of those scales. The proposed project will use genome-wide data from a pelagic copepod (Pleuromamma xiphias), coupled with multiple environmental variables collected across a spatio-temporal gradient, to assess what determines the scale of population connectivity in the open sea, and infer how these factors influence the response of Atlantic Ocean P. xiphias populations to climate change. Specifically, the fellow will examine the following hypotheses: 1) Biological and physical environment are selective forces shaping population structure in P. xiphias; 2) Migration rate is high among sites within the North and South Atlantic gyres, but low at the poleward edges of each gyre and across the equator; 3) P. xiphias populations will be increasing in abundance and expanding toward the poleward range of their distribution, while sites at the equatorial edges will be undergoing bottlenecks. This work will be conducted under the mentorship of Erica Goetze, PhD in the School of Ocean and Earth Science and Technology (SOEST) at the University of Hawai'i at Manoa. Each of the comparisons (genes, sites, time points, environmental variables) will contribute incremental insights into the genetic structuring of pelagic zooplankton. Combined, they have the potential to transform the way we think about population connectivity in the open ocean, and shed new light on the potential adaptive capacity of pelagic copepods in a changing climate.