SG/RUI: Collaborative Research: The evolution of extreme phenotypic convergence across fish lineages in the hyper-diverse lower Congo River

SG/RUI：合作研究：高度多样化的刚果河下游鱼类谱系极端表型趋同的演化

• 批准号: 2105500
• 负责人: Susan Alter
• 金额: $ 8.65万
• 依托单位: University Corporation at Monterey Bay
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-10-01 至 2023-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2105500&HistoricalAwards=false
• 关键词: SG; RUI; Collaborative; Research; evolution; SG; RUI; Collaborative; Research; evolution

The lower Congo River is one of the most extreme freshwater habitats on Earth, with some of the planet's largest whitewater rapids and deepest underwater canyons. These rapids, eddies and canyons are home to an extraordinary array of fishes, many of which are striking in appearance and exhibit numerous adaptations to life in turbulent, high-energy waters. In such extreme habitats, evolution sometimes produces independently derived yet remarkably similar traits. For example, many distantly related fishes in the lower Congo have independently lost body coloration, have reduced or absent eyes, and share similar elongate body shapes and modified sensory features. How and when did these unusual features evolve? These striking examples of convergence (when similar traits evolve independently) strongly suggest a shared signature of selection, likely in response to the extraordinary hydrology of the river itself. This research project will examine the phylogenetic and morphological basis of convergence in the lower Congo fish fauna to address fundamental questions about the mechanisms that promote adaptation and diversification in extreme environments. These analyses will provide new insights into how limbs are reduced or lost in diverse fish lineages that can then be applied more broadly to other vertebrates. U.S. undergraduate students from a minority-serving, principally undergraduate institution will receive broad training in tropical field studies, molecular systematics, and African biodiversity more generally. Findings from the study will be incorporated within both graduate and undergraduate courses, and results will be disseminated more broadly by a Science Explorations video and project website. Other data will be deposited in online, open-access repositories. This study investigates a newly discovered system of complex in situ phenotypic convergence among members of phylogenetically diverse fish lineages. Two major datasets will be generated and integrated: 1) a phylogenetic framework based on ultra-conserved elements to determine the topology and temporal framework of within-clade divergences; and 2) a detailed morphological characterization of within-group convergence utilizing a range of quantification and visualization techniques, including 3-dimensional computed tomography (3D CT) reconstruction, histology, scanning electron microscopy (SEM), and multivariate morphometric approaches. Using these datasets, the study will investigate how rapidly these phenotypes arose, morphological correspondence of convergence within and between clades, and whether multiple traits evolved in concert. By conducting in-depth, foundational phylogenetic, anatomical, and morphometric analyses of this unparalleled natural experiment, the study will potentially transform understanding of the variety of mechanisms by which convergent phenotypes have repeatedly evolved across deep phylogenetic time. This research will also generate a broadly useful resource for future comparative studies with similar convergent systems (e.g. Astyanax cavefishes) and will establish the foundation for determining the genomic basis of these phenotypes.

下刚果河是地球上最极端的淡水栖息地之一，地球上最大的白水急流和水下最深的水下峡谷。这些急流，涡流和峡谷是各种各样的鱼类的所在地，其中许多是醒目的外观，并在湍流，高能水域中暴露了许多适应生命。在如此极端的栖息地中，进化有时会产生独立但相似的特征。例如，下刚果中许多明显相关的鱼具有独立损失的身体颜色，减少或吸收了眼睛，并具有相似的细长体形和改良的感觉特征。这些异常特征如何以及何时发展？这些惊人的收敛例子（当类似的特征独立发展时）强烈暗示了选择的共同签名，这可能是响应河流本身的非凡水文学的响应。该研究项目将研究刚果鱼类动物区系中融合的系统发育和形态学基础，以解决有关促进极端环境中适应和多样化的机制的基本问题。这些分析将提供新的见解，以了解如何在多样性的鱼谱系中减少或丢失，然后将其更广泛地应用于其他脊椎动物。来自少数族裔的本科生，主要是本科机构将在热带野外研究，分子系统学和非洲生物多样性方面接受广泛的培训。该研究的结果将纳入研究生和本科课程中，结果将通过科学探索视频和项目网站更广泛地传播结果。其他数据将存入在线，开放访问存储库中。这项研究调查了系统发育多样的渔线成员之间新发现的复杂原位表型收敛系统。将生成和集成两个主要数据集：1）基于超保守元素的系统发育框架，以确定脱落内部分歧的拓扑和临时框架； 2）利用一系列量化和可视化技术的详细形态表征，包括3维计算机断层扫描（3D CT）重建，组织学，扫描电子显微镜（SEM）和多变量形态计量方法。使用这些数据集，该研究将研究这些表型产生的速度，进化枝内和进化枝之间的形态学对应关系，以及多种特征是否在协同中演变。通过深入进行这种无与伦比的自然实验的基础系统发育，解剖学和形态分析，该研究将有可能改变人们对收敛表型在深层系统发育时间中反复演变的机制的理解。这项研究还将为未来的比较研究（例如Astyanax Cavefishes）生成广泛有用的资源，并将为确定这些表型的基因组基础建立基础。