Phylogenomic Study of Adaptive Radiation in Antarctic Fishes

了解生物群如何应对气候变化，对于评估人类活动的影响以及理解过去的气候变化如何在很长一段时间内塑造生物多样性至关重要。占据南极洲附近近岸海洋栖息地的鱼类被一组密切相关的物种所主宰，这些物种被称为Notothenioides。南极气候的戏剧性变化似乎对这一经济上重要的鱼类的起源和进化多样化具有重要意义。南极洲的鱼类化石沉积是在该大陆经历较温和的温度时形成的，这表明该地区是更多样化的鱼类种类的家园。今天，南大洋的水域非常寒冷，通常在零度以下，但无齿类鱼类表现出了许多适应这种恶劣海洋栖息地的能力，包括抗冻蛋白的存在。这项研究项目将收集数百个基因的DNA序列，以推断几乎所有124个无尾类物种的谱系关系，并使用数学技术来估计物种和谱系的年龄。研究人员了解到南极洲鱼类进化分化的时间，将使研究人员能够评估南极洲以前主要气候变化的时间是否与现代南大洋鱼类动物群形成的关键事件有关。该项目还将推动NSF向公众提供科学发现和培训新一代科学家的目标。该项目将通过自然历史博物馆展览和其他公开讲座，支持面向青少年群体和普通公众的教育推广活动。它将为研究生和博士后研究学者提供专业培训机会。适应性辐射主要是在岛屿生态系统中研究的，在这种情况下，谱系经历了与生态分化相一致的高进化多样性。虎鱼类主宰南大洋的鱼类动物群，并展示抗冻糖蛋白，使其能够占据零度以下的水域。Notothenioid被认为是海洋鱼类中仅有的适应辐射的例子之一，但对多样化和辐射到不同生态生境的进化史知之甚少。这项研究将为几乎所有124个公认的诺氏类物种生成物种系统发育(进化史)，以研究这一谱系中适应性辐射的机制。通过使用下一代DNA测序和相关技术从大约350个基因样本中推断出系统发育。博物馆标本的形态计量学数据被用来调查形态多样化的节奏，并确定谱系多样性比率与形态差异的来源之间是否存在相关性。我们将通过与古气候记录比较，确定过去全球气候变化的例子是否塑造了这种适应极地的鱼类谱系的进化多样性。

Understanding how groups of organisms respond to climate change is fundamentally important to assessing the impacts of human activities as well as understanding how past climatic shifts have shaped biological diversity over deep stretches of time. The fishes occupying the near-shore marine habitats around Antarctica are dominated by one group of closely related species called notothenioids. It appears dramatic changes in Antarctic climate were important in the origin and evolutionary diversification of this economically important lineage of fishes. Deposits of fossil fishes in Antarctica that were formed when the continent was experiencing milder temperatures show that the area was home to a much more diverse array of fish lineages. Today the waters of the Southern Ocean are very cold, and often below freezing, but notothenioids fishes exhibit a number of adaptions to live in this harsh set of marine habitats, including the presence of anti-freeze proteins. This research project will collect DNA sequences from hundreds of genes to infer the genealogical relationships of nearly all 124 notothenioid species, and use mathematical techniques to estimate the ages of species and lineages. Knowledge on the timing of evolutionary divergence in notothenioids will allow investigators to assess if timing of previous major climatic shifts in Antarctica are correlated with key events in the formation of the modern Southern Ocean fish fauna. The project will also further the NSF goals of making scientific discoveries available to the general public and of training new generations of scientists. The project will support educational outreach activities to teenager groups and to the general public through a natural history museum exhibit and other public lectures. It will provide professional training opportunities for graduate students and a postdoctoral research scholar. Adaptive radiation, where lineages experience high rates of evolutionary diversification coincident with ecological divergence, is mostly studied in island ecosystems. Notothenioids dominate the fish fauna of the Southern Ocean and exhibit antifreeze glycoproteins that allow occupation of the subzero waters. Notothenioids are noted as one of the only examples of adaptive radiation among marine fishes, but the evolutionary history of diversification and radiation into different ecological habitats is poorly understood. This research will generate a species phylogeny (evolutionary history) for nearly all of the 124 recognized notothenioid species to investigate the mechanisms of adaptive radiation in this lineage. The phylogeny is inferred from approximately 350 genes sampled using next generation DNA sequencing and related techniques. Morphometric data are taken for museum specimens to investigate the tempo of morphological diversification and to determine if there are correlations between rates of lineage diversification and the origin of morphological disparity. The patterns of lineage, morphological, and ecological diversification in the notothenioid radiation will be compared to the paleoclimatic record to determine if past instances of global climate change have shaped the evolutionary diversification of this lineage of polar-adapted fishes.