Revealing the factors that control evolutionary diversification in birds

点击翻译按钮获取中文摘要

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.