Revealing the factors that control evolutionary diversification in birds

我的研究试图了解鸟类是如何进化和多样化的。虽然我们知道新物种的形成(物种形成)和新特征的进化(表型进化)的基本机制，但我们对这两个过程如何在时间和空间上相互作用以及它们如何受到灭绝、扩散、地理和生态因素的影响知之甚少。了解这些问题对当前的生物多样性危机具有重要意义，因为它揭示了物种形成和灭绝之间平衡的本质，评估了生物多样性适应环境变化的速度，并确定了可能影响生物多样性恢复的因素。 这些活动将侧重于使用DNA和形态数据来划定物种范围，并评估它们之间的进化关系。然后，这些进化树将被用于使用比较方法和统计建模技术来估计进化过程及其时间动力学的重要参数。关于扩散对多样化的影响，我正在调查从机翼形态评估的飞行性能估计作为鸟类物种扩散能力的替代指标的使用情况。 我将重点研究鸟类在两个尺度上的多样性。在较大范围内，我将重点介绍所有现代鸟类(新鸟属)。我将使用基因组和形态数据集来生成一个经过时间校准的现代鸟类进化树，包括每个科至少一个有代表性的物种。使用一种新的校准分子时钟的方法，我们最近发现行星温度和鸟类多样性比率之间存在很强的相关性。随着改进的分歧时间估计和更全面的鸟类多样性样本，我将调查这种相关性的原因。除了增加分类学上的代表性外，我还将通过使用校准分子钟的新方法以及确定将用于设定时间尺度的鸟类化石的亲和力来改进先前的估计。 在较小的范围内，我将重点介绍南美鸟类的进化。就像加拉帕戈斯群岛上的达尔文雀一样，南美鸟类在谱系数量以及形态和生态特征上都存在多样性，但它们的多样性程度要大得多，而且覆盖了整个大陆。因此，对南美鸟类的研究可以揭示大陆上生物多样性的形成过程。重建南美进化树的工作正在进行中，但主要的努力将是解决几个物种复合体中关于物种限制的不确定因素，并建立一个准确的时间尺度。

My research seeks to understand how birds evolved and diversified. Although we know the basic mechanisms of formation of new species (speciation) and evolution of novel traits (phenotypic evolution), we know little about how these two processes interact through time and space and how they are affected by extinction, dispersal, geography, and ecological factors. Understanding these issues has important implications for the current biodiversity crisis by revealing the nature of the balance between speciation and extinction, assessing how fast biodiversity can adapt to environmental change, and identifying the factors that may affect biodiversity recovery. The activities will focus on using DNA and morphological data to delimit species and estimate the evolutionary relationships among them. These evolutionary trees will then be used for estimating important parameters of the evolutionary process and its temporal dynamics using comparative methods and statistical modeling techniques. Regarding the influence of dispersal on diversification, I am investigating the use of estimates of flight performance, as assessed from wing morphology, as a proxy for the dispersal ability of bird species. I will focus on the study of bird diversification at two scales. On a large scale, I will focus on all modern birds (Neornithes). I will use genomic and morphological datasets to generate a time-calibrated evolutionary tree of modern birds including at least one representative species of each family. Using a novel method for calibrating molecular clocks, we recently found a strong correlation between planetary temperatures and avian diversification rates. With improved divergence-time estimates and a more comprehensive sample of avian diversity, I will investigate the causes of such a correlation. In addition to increased taxonomic representation, I will improve previous estimates by using new method for calibrating molecular clocks and by determining the affinities of fossils birds that will be used for setting the time scale. On a smaller scale, I will focus on the evolution of South American birds. Like Darwin's finches in the Galapagos islands, South American birds diversified both in number of lineages and in morphological and ecological traits but they have done so to a much greater degree and across an entire continent. Therefore, the study of South American birds can reveal the process that generated biodiversity on continents. Work towards reconstructing evolutionary trees of the South American is on-going but a major endeavor will be to resolve uncertainties regarding species limits in several species complexes and establish an accurate time scale.