CAREER: At The Convergence of Life Cycles and Reproduction: Insights Into the Diversity of Life

该奖项部分由2021年美国救援计划法案（公法117-2）资助。此外，该项目由环境生物学部和刺激竞争研究的既定计划（EPSCoR）资助。所有多细胞生物在其生命周期中都要经历不同的阶段。这些阶段可能在细胞数量、每个细胞的染色体数量或染色体上遗传信息的排列上有所不同。例如，人类有两个生命阶段：单倍体阶段由卵子或精子组成，二倍体阶段从胚胎延伸到成人。这些交替的阶段构成了一个生命周期。在整个自然界中，生命周期的持续时间和复杂性有着惊人的多样性。这个项目将通过将生命周期和生殖变异的预测联系起来，扩大我们对这种多样性的理解。了解这两种基本生物特征——生命周期和繁殖——的融合对于预测物种可能如何应对环境挑战至关重要。普通的花园实验和对广泛分布的海藻的DNA分析将使研究人员能够探索这些联系。这项研究计划还为本科生提供了为期一个月的实地课程，让学生了解海洋和淡水生态系统中的藻类。本课程的学生也为两个主要的研究目标收集数据。此外，研究还与阿拉巴马州水观察组织和卡哈巴河协会进行协调。与这些团体的协调提高了伯明翰和整个阿拉巴马州的科学和环境素养。研究人员利用了一种广泛存在的海藻，这种海藻已经成为入侵物，它已经被引入北半球。入侵后，二倍体期占优势。该项目调查了这种藻类的生命周期如何对入侵过程做出反应，从而允许测试生命周期和繁殖之间的联系。两组实验解决了两个主要问题。第一组实验区分了生态模型和遗传模型的预测。在这里，研究人员进行了普通的花园实验，以揭示不同的基因型如何响应对潮间带藻重要的环境条件，如盐度和温度。根据生态学的预测，这两个生命阶段的反应应该不同。第二组实验评估二倍体和单倍体阶段的相对长度如何影响生殖系统。为了调查这个问题，从海藻的本地和引进范围的自然种群中取样DNA。种群遗传分析确定单倍体期延长是否影响海藻繁殖。具体来说，它可以检测海藻是通过异交、自交受精还是无性繁殖进行交配，以及这种繁殖策略是否因不同的生命周期类型而变化。总之，这些实验的结果为生命周期和生殖策略相互依赖的方式提供了独特的见解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识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 part under the American Rescue Plan Act of 2021 (Public Law 117-2). In addition, this project is funded by the Division of Environmental Biology and the Established Program to Stimulate Competitive Research (EPSCoR).All multicellular organisms pass through different stages in their life cycle. These stages may differ in the number of cells, the number of chromosomes per cell, or the arrangement of genetic information on the chromosomes. For example, humans have two life stages: the haploid stage consists of eggs or sperm, and the diploid stage extends from embryo to adult. These alternating stages make a life cycle. Across the natural world, there is an amazing diversity in the duration and complexity of life cycles. This project will expand our understanding of this diversity by linking predictions about life cycles and reproductive variation. Understanding the convergence of these two fundamental organismal traits – the life cycle and reproduction – is crucial for predicting how species are likely to respond to environmental challenges. Common garden experiments and DNA analysis of a widespread seaweed will allow the investigators to explore these connections. The research plan is enhanced by a month-long field course for undergraduates, in which students learn about algae in marine and freshwater ecosystems. Students in this course also collect data for the two main research aims. In addition, research is coordinated with the Alabama Water Watch and the Cahaba River Society. Coordination with these groups increases scientific and environmental literacy in Birmingham and across Alabama.The researchers leverage a widespread seaweed that has become invasive where it has been introduced in the Northern Hemisphere. Upon invasion, the diploid stage predominates. The project investigates how the life cycle of this alga has responded to the process of invasion, thus permitting a test of the connections between life cycles and reproduction. Two sets of experiments address two major questions. The first set of experiments distinguish between predictions of ecological and genetic models. Here, researchers carry out common garden experiments to reveal how different genotypes respond to environmental conditions important to an intertidal alga, such as salinity and temperature. According to ecological predictions, the two life stages should respond differently. The second set of experiments evaluates how the relative length of the diploid and haploid stages affect the reproductive system. To investigate this question, DNA is sampled from natural populations of the seaweed’s native and introduced range. Population genetic analysis determines whether a prolonged haploid stage affects seaweed reproduction. Specifically, it can detect whether the seaweeds mate by outcrossing, self-fertilization or asexual propagation, and whether this reproductive strategy varies depending on the different type of life cycle. Together, the results of these experiments provide unique insight into the ways in which life cycles and reproductive strategies are interdependent.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.