Origins and maintenance of diversity

点击翻译按钮获取中文摘要

Where does biodiversity come from, and why does it vary across the globe? These are important questions to answer before we can accurately predict the future impacts of human activities on the world. The long-term goal of my research program is to better understand (I) how new species form, (II) when and how these new species expand their distributions to coexist with one another, and (III) the causes of broad geographic variation in diversity. (I) To study how new species form, we will examine one of the newest species of bird to evolve - the Golden-crowned Sparrow (Zonotrichia atricapilla) - and the traits that keep this species distinct from its closest relative, the White-crowned Sparrow (Z. leucophrys). Using experiments in aviaries, we will ask females which species they prefer, and what traits they use to make their decision. We will then use cross-fostering experiments - where one species is raised by the other - to test the hypothesis that choice of mates is based on imprinting on their parents at an early age. (II) Once new species form, they may take a long time before they actually come to coexist with one another. We will examine the progression from species formation to coexistence together in warblers (Parulidae: Dendroica) occurring in eastern Canada. Using genetic data to estimate how long ago species separated, we will examine their spatial distributions, ecology and behavioural interactions and how these change with the amount of time since divergence. (III) The cause of the latitudinal increase in diversity towards the equator is one of the greatest unsolved questions in biology. We are studying how patterns of evolution vary with latitude, specifically examining why we see evidence for faster rates of evolution at higher latitudes, contrary to what we might expect. We will use genetic, biogeographic, museum specimens, and old fashioned field work to test among hypotheses to explain faster evolution in high latitude birds, and further ask how this relates to latitudinal variation in rates of formation of new species. Overall, the proposed work will significantly improve our understanding of biodiversity, and will contribute to other Canadian research at the forefront of this field.