Dimensions: Links Between Spectral Irradiance and Cryptophyte Biodiversity in Environments from Ponds to Oceans

维度：从池塘到海洋的环境中光谱辐照度与隐植物生物多样性之间的联系

• 批准号: 1542555
• 负责人: Tammi Richardson
• 金额: $ 195.65万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1542555&HistoricalAwards=false
• 关键词: Dimensions; Links; Between; Spectral; Irradiance

In aquatic environments, microscopic algae known as phytoplankton are important primary producers. Through photosynthesis, these organisms fix carbon dioxide into the organic carbon molecules that fuel life in ponds, rivers, lakes and oceans. The color of light available for photosynthesis varies among environments, e.g., the deep blue ocean vs. a black water river. In order to live in a particular environment, phytoplankton must have photosynthetic pigments that are tuned to absorbing the colors of light available. This project focuses on the cryptophytes, a relatively uncharacterized group of phytoplankton, that are abundant in a wide range of aquatic habitats ranging from small ponds to oceans. Cryptophytes use phycobilin pigments to capture light energy; these pigments allow cryptophytes to photosynthesize in light environments that are poorly exploited by other types of algae. The project goals are: (1) to characterize the ecological distribution and taxonomic diversification of cryptophyte species, (2) to determine the effectiveness of their light capture in different light environments, and (3) to characterize the molecular evolutionary pathways of critical light capture genes. Understanding these links is important to predicting how changes in land-use (like deforestation and urbanization, both of which impact the color of light in downstream watersheds) will affect aquatic productivity. This project will provide training for a post-doc, 2-4 graduate students, and 10 undergraduates. Through a partnership with Morris College and other University of South Carolina programs, underrepresented minorities will be recruited into summer fellowships. Novel cryptophyte strains will be deposited in living culture collections for use by other researchers. This project's central question is deceptively simple: How do functional, genetic, and phylogenetic diversity interact in the ecological diversification of cryptophytes with respect to light environment? The researchers will conduct an integrative research program on the biodiversity of cryptophytes to understand how environmental variation in spectral irradiance is associated with the physiological diversity of light capture in cryptophytes in the context of their historical diversification. This work integrates several components: (1) Field sampling in water bodies ranging from small ponds to oceans to identify the specific light environments in which strains live, to determine the pigments that cryptophytes produce in those habitats, and to identify novel species; (2) Phenotypic studies to determine how variation in spectral irradiance (light color) influences light capture, photosynthesis, and growth of diverse taxa. These will also determine spectral absorption of phycobilins in strains throughout the cryptophyta; (3) Construction of a well-supported phylogeny based on sequencing nucleomorph genomes of ~200 strains; (4) Analyses of molecular evolution of key light capture genes, in particular those that encode the alpha and beta subunits of the cryptophyte phycobiliproteins, and those involved in the phycobilin synthesis pathway; (5) Experimental evolution to test the ability of diverse strains of cryptophytes to evolve into new light niches; (6) Experimental transcriptomics to identify the functional responses of diverse strains to variation in spectral irradiance; and (7) Phylogenetically-informed tests of the associations between habitat, molecular evolution, organismal performance, and spectral absorbance. Ultimately, this work should be a transformative contribution to our understanding of the diversification of photosynthesis and the role of that diversification in the ecological distribution of cryptophytes.

在水环境中，被称为浮游植物的微小藻类是重要的初级生产者。通过光合作用，这些生物将二氧化碳固定在有机碳分子中，这些有机碳分子为池塘、河流、湖泊和海洋中的生命提供燃料。可用于光合作用的光的颜色因环境而异，例如，深蓝色的海洋和黑色的河流。为了在特定的环境中生存，浮游植物必须有光合色素，这种色素可以吸收可用的光的颜色。该项目的重点是隐芽植物，这是一组相对不具特征的浮游植物，在从小池塘到海洋的广泛水生生境中大量存在。隐芽植物使用藻胆蛋白色素来捕捉光能；这些色素允许隐芽植物在光环境中进行光合作用，而其他类型的藻类对光环境的利用很差。该项目的目标是：(1)确定隐芽植物物种的生态分布和分类多样性，(2)确定它们在不同光环境中的光捕获效果，(3)描述关键光捕获基因的分子进化途径。了解这些联系对于预测土地利用的变化(如森林砍伐和城市化，这两种变化都会影响下游流域的光线颜色)将如何影响水生生产力非常重要。该项目将为1名博士后、2-4名研究生和10名本科生提供培训。通过与莫里斯学院和南卡罗来纳大学的其他项目合作，未被充分代表的少数族裔将被招募到夏季奖学金中。新的隐芽菌株将被保存在活的培养标本中，供其他研究人员使用。这个项目的中心问题看起来很简单：关于光环境，功能、遗传和系统发育多样性如何在隐芽植物的生态多样性中相互作用？研究人员将对隐芽植物的生物多样性进行综合研究计划，以了解在其历史多样化的背景下，环境中光谱辐照度的变化与隐芽植物光捕获的生理多样性之间的关系。这项工作包括几个部分：(1)在从小池塘到海洋的水体中进行实地采样，以确定菌株生活的特定光环境，确定隐芽植物在这些生境中产生的色素，并确定新物种；(2)表型研究，以确定光谱辐照度(光色)的变化如何影响光捕获、光合作用和不同类群的生长。这也将决定藻胆蛋白在整个隐孢子纲菌株中的光谱吸收；(3)基于对约200株细菌核形态基因组测序的支持良好的系统发育；(4)关键光捕获基因的分子进化分析，特别是编码隐藻藻胆蛋白的α和β亚基的那些基因，以及参与藻胆蛋白合成途径的那些基因；(5)测试不同隐藻株进化成新的光生态位的能力的实验进化；(6)鉴定不同菌株对光谱辐射变化的功能反应的实验转录学；以及(7)对栖息地、分子进化、生物性能和光谱吸光度之间的关联进行的系统发育测试。归根结底，这项工作应该对我们理解光合作用的多样性以及这种多样性在隐芽植物生态分布中的作用做出革命性的贡献。