CAREER: Phylogenetic scale-dependency of the patterns and processes of quantitative trait evolution

所有的生命都由共同的祖先联系在一起，遗传和生理上的相似之处揭示了这一点。这被描绘成一棵生命树，一个根分裂成许多分支，这些分支又分裂成更小的分支，依此类推，形成被称为分支的嵌套物种群体。为了了解产生地球上生命惊人多样性的过程，生物学家和古生物学家在这棵树上进行了各种规模的调查，比较了不同分类级别(例如，属、科、目)、大小或年龄的支系。虽然很少得到承认，但目前的假设是，在一个标尺上确定的结论可以适用于所有其他标尺。然而，这一关键假设还有待验证。这项研究将使用高度多样化的硬骨鱼，包括大约一半的脊椎动物物种，调查不同规模的可预测结果。研究人员将确定鱼类体型演变的模式是相同的、随机的还是系统地在不同尺度上变化。确定这些模式的可预测性以及从中推断出的过程，将决定在一个尺度上得出的结论是否以及如何适用于另一个尺度。这将对在不同规模下工作的各个领域的综合结果产生广泛的影响，特别是将化石研究和活生物体研究联系起来的能力。该项目还将改善获得本科生研究机会的机会，通过发展基于课堂的本科生研究体验将学生纳入科学发现过程，并出版相关的开放教育资源。这个项目将建立一个关于系统发育规模如何影响数量性状进化模式和过程的实证理解。为了实现这一目标，研究人员将在他们现有的硬骨动物体型数据库的基础上，建立来自6,000个物种的大约16,000个样本。他们将对来自大约4,500个物种的另外17,500个样本进行测量，以提供物种内和系统发育中较浅节点的更密集样本。将使用两种相辅相成的跨尺度分析方法来确定尺度依赖性及其可预测性。第一个将应用数量性状进化的混合高斯系统发育模型，以确定参数变化；第二个将使用更传统的系统发育比较方法，一次调查一个尺度的模式。使用四种界定尺度的方法：枝龄、枝条大小、树深和分类排名，研究人员还将量化所选择的尺度定义方法对尺度依赖模式的影响。模拟将被用来调查统计伪影的可能性以及方法和数据限制的影响。这些分析将决定系统发育规模依赖是例外还是规则。该项目还将包括本科生、研究生和博士后水平的培训机会。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

All life is linked by common ancestry, as revealed by genetic and physical similarities. This is depicted as a tree of life with a single root splitting into many branches, which further split into smaller branches and so on, forming nested groups of species known as clades. To understand the processes that generated the astounding diversity of life on earth, biologists and paleontologists conduct investigations at a variety of scales across this tree, comparing amongst clades of different taxonomic rank (e.g., Genus, Family, Order), size or age. Although rarely acknowledged, it is currently assumed that the conclusions identified at one scale can be applied to all other scales. However, this critical assumption is yet to be validated. This research will investigate how predictable results are across scales, using the highly diverse teleost fishes, which includes approximately half of all vertebrate species. The researchers will determine if patterns of fish body shape evolution are identical, random or vary systematically across scales. Establishing the predictability of these patterns, and processes inferred from them, will determine if and how conclusions drawn at one scale can be applied to another scale. This will have broad implications for synthesizing results across fields that work at different scales and in particular, the ability to connect studies on fossils and living organisms. This project will also improve access to undergraduate research opportunities, integrating students into the scientific discovery process through the development of a Classroom-based Undergraduate Research Experience, and publishing associated Open Educational Resources. This project will build an empirical understanding of how phylogenetic scale influences patterns and processes of quantitative trait evolution. To accomplish this objective the researchers will build upon their existing teleostean body shape dataset of approximately 16,000 specimens from 6,000 species. They will add measurements on a further 17,500 specimens from around 4,500 species to provide denser sampling within species and at shallower nodes in the phylogeny. Two complementary approaches to cross-scale analysis will be used to identify scale-dependency and its predictability. The first will apply mixed Gaussian phylogenetic models of quantitative trait evolution to the full phylogenetic extent to identify parameter shifts; the second will investigate patterns one scale at a time using more traditional phylogenetic comparative methods. Using four ways of delimiting scale: clade age, clade size, tree depth and taxonomic rank, the researchers will also quantify how patterns of scale-dependency are influenced by the method chosen to define scale. Simulations will be used to investigate the potential for statistical artifacts and the influence of methodological and data limitations. These analyses will determine whether phylogenetic scale-dependency is the exception or the rule. The project will also include training opportunities at the undergraduate, graduate student and postdoctoral levels.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.