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

在水生环境中，被称为浮游植物的微型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到有机碳分子中，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随环境而变化，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，浮游植物必须具有能够吸收可用光的颜色的光合色素。这个项目的重点是隐藻，一个相对不具特色的浮游植物群体，丰富的水生栖息地，从小池塘到海洋。隐藻使用藻胆素色素来捕获光能;这些色素允许隐藻在其他类型藻类利用不足的光环境中进行光合作用。该项目的目标是：（1）研究隐藻的生态分布和分类多样性;（2）研究隐藻在不同光环境下的光捕获效率;（3）研究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，两者都会影响下游流域的光线颜色）将如何影响水产生产力非常重要。本项目将为一名博士后、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州其他大学的合作，代表性不足的少数民族将被招募到夏季奖学金。新的隐藻菌株将被保存在活的培养物中，供其他研究人员使用。这个项目的中心问题是看似简单：功能，遗传和系统发育多样性如何相互作用的生态多样性的隐藻相对于光环境？研究人员将对隐藻的生物多样性进行综合研究，以了解光谱辐照度的环境变化如何与隐藻在其历史多样化背景下的光捕获生理多样性相关。这项工作整合了几个组成部分：（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，以确定隐藻在这些栖息地产生的色素，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。（3）基于~200个菌株的核形基因组测序构建支持性良好的遗传学（biogeny）;（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，以及参与藻胆蛋白合成途径的那些;（5）实验进化，以测试不同菌株的隐芽植物进化成新的光生态位的能力;（6）实验转录组学，以确定不同菌株的光谱辐照度变化的功能反应;（7）栖息地，分子进化，生物体性能和光谱吸收之间的关联的系统发育测试。最终，这项工作应该是一个变革性的贡献，我们的光合作用的多样化和多样化的作用，在生态分布的隐藻的理解。

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.