How do palaeontological data refine our understanding of adaptive radiation and the evolution of modern biodiversity?

古生物学数据如何完善我们对适应性辐射和现代生物多样性进化的理解？

基本信息

批准号：
NE/J022632/1
负责人：
Matthew Friedman
金额：
$ 35.77万
依托单位：
University of Oxford
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2012
资助国家：
英国
起止时间：
2012 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FJ022632%2F1
关键词：
How do palaeontological data refine

项目摘要

Swordfishes (needle-nosed predators of the high seas), flounders (gastronomically familiar and bizarrely asymmetrical bottom dwellers), remoras (literal hangers-on that hitch rides on sharks using a suction cup on their heads): few fishes, or indeed vertebrates, show more strikingly different anatomies or modes of life. Divergent as they are, genetic studies indicate that these fishes, as well as several others, are closely related, forming a bough in the tree of life called Carangimorpha. Cases like this, where organisms with shared ancestry branch out over time to assume divergent bodyplans and lifestyles, are known as adaptive radiations. Previous research on this topic has focused on living groups with poor fossil records, like anole lizards, cichlid fishes, and Darwin's famous finches. However, fossils are the only direct means of timing evolutionary events, and yield unique evidence of anatomies pruned from the tree of life by extinction; as such, they are critical in understanding how modern biodiversity came to be. We will study this exceptional group of fishes as a laboratory to not only understand how their specialisations arose, but also explore the ways in which fossils can be especially useful for answering questions of biodiversity and evolution. Specifically, we will ask: (1) what are the steps leading to peculiar carangimorph body 'designs'; (2) when in geological time did these changes occur?; and (3) what do fossils tell us about the speed and manner in which these changes took place?Fossils are critical in solving these problems. For instance, recent discoveries revealed how flatfishes evolved to have both eyes on one side of their head. Such transitional forms are typically rare, but the diversity of living carangimorphs is complemented by a trove of complete fossils. Modern preparation (chemical treatment or methods akin to sandblasting) and imaging (CT scan) techniques can extract fossils from surrounding rock. We will uncover details of exceptional fossils that show the early stages in the evolution of remarkable adaptations of living carangimorphs, including the rapier-like snout of billfishes and the suction disc of remoras.Fossils cannot speak for themselves and we cannot simply trace evolution by peeling back rock layers. We must discover the relationships of fossils to living species. We will combine palaeontological data with anatomy and DNA data from modern fishes to place fossils in a tree alongside living relatives, allowing us to reconstruct the transformations leading to specialized modern bodyplans. Including both extinct and living species is also important because fossils influence estimated relationships among living species and vice versa.To build a timeline for carangimorph evolution, we need to find out when in Earth's history each branch in its family tree split off. Fossilization is a rare event, and so even the oldest fossil of a particular branch might be a relatively late arrival. We therefore need to combine our fossil data with an indirect approach known as the molecular clock. If we know the rate at which genetic mutations build up, we can estimate how long ago living species split from each other and produce a 'time tree': a family tree with an absolute time scale. With these components in place, we can test how fossils impact our understanding of adaptive radiation and the evolution of biodiversity, using carangimorphs as a test case. Our time tree allows us to apply statistical tools for finding the rate at which anatomical features changed over time. This can be used to see whether change was rapid early in evolutionary history or whether it was slow and gradual, and whether rates varied between marine and freshwater environments. We will conduct our analyses with and without fossils, allowing us to decide whether those based only on modern data might be misleading, and if other biologists should therefore strive to include extinct species in their studies.

剑鱼（公海的针鼻掠食者）、比目鱼（在美食中常见且奇怪的不对称海底生物）、鲹鱼（用头上的吸盘搭在鲨鱼身上的食客）：很少有鱼类，甚至是脊椎动物，显示出更加显着不同的解剖结构或生活方式。尽管它们各不相同，但基因研究表明，这些鱼类以及其他几种鱼类密切相关，在生命之树上形成了一个分支，称为 Carangimorpha。在这种情况下，具有共同祖先的生物体随着时间的推移而分支，呈现出不同的身体结构和生活方式，被称为适应性辐射。此前关于这一主题的研究主要集中在化石记录较少的生物群体上，例如变色蜥蜴、慈鲷和著名的达尔文雀。然而，化石是对进化事件进行计时的唯一直接手段，并提供了独特的解剖学证据，证明生命之树因灭绝而被修剪掉。因此，它们对于理解现代生物多样性是如何形成的至关重要。我们将作为实验室研究这一特殊的鱼类，不仅了解它们的特化是如何产生的，而且探索化石对于回答生物多样性和进化问题特别有用的方式。具体来说，我们会问：（1）导致奇特的carangimorph身体“设计”的步骤是什么？ (2) 这些变化发生在地质时期的什么时候？（3）化石告诉我们这些变化发生的速度和方式是什么？化石对于解决这些问题至关重要。例如，最近的发现揭示了比目鱼如何进化成双眼长在头部的一侧。这种过渡形式通常很罕见，但现存的carangimorphs的多样性得到了大量完整化石的补充。现代制备（化学处理或类似于喷砂的方法）和成像（CT 扫描）技术可以从周围的岩石中提取化石。我们将揭开特殊化石的细节，这些化石展示了现存鲫鱼形态的显着适应进化的早期阶段，包括长嘴鱼的剑状鼻子和鲫鱼的吸盘。化石不能为自己说话，我们也不能简单地通过剥皮来追踪进化过程后岩层。我们必须发现化石与现存物种的关系。我们将把古生物学数据与现代鱼类的解剖学和 DNA 数据结合起来，将化石与活着的亲戚一起放在树上，使我们能够重建导致专门的现代身体规划的转变。包括灭绝物种和现存物种也很重要，因为化石会影响现存物种之间的关系估计，反之亦然。为了建立carangimorph进化的时间表，我们需要找出地球历史上其家谱中的每个分支何时分裂。化石是一种罕见的事件，因此即使是特定分支最古老的化石也可能是相对较晚到达的。因此，我们需要将化石数据与称为分子钟的间接方法结合起来。如果我们知道基因突变形成的速度，我们就可以估计生命物种在多久之前彼此分裂并产生“时间树”：具有绝对时间尺度的家谱。有了这些组件，我们就可以使用 carangimorphs 作为测试用例来测试化石如何影响我们对适应性辐射和生物多样性进化的理解。我们的时间树使我们能够应用统计工具来查找解剖特征随时间变化的速率。这可以用来了解进化历史早期的变化是否迅速，或者是否缓慢且渐进，以及海洋和淡水环境之间的变化率是否不同。我们将在有化石和没有化石的情况下进行分析，从而使我们能够确定仅基于现代数据的分析是否可能具有误导性，以及其他生物学家是否应该努力将灭绝物种纳入他们的研究中。