Testing mechanisms of speciation and hybridization in terrestrial vertebrates

陆生脊椎动物物种形成和杂交的测试机制

• 批准号: 311931-2010
• 负责人: Irwin, Darren
• 金额: $ 1.82万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=457207
• 关键词: Testing; mechanisms; speciation; hybridization; terrestrial

There is abundant evidence for the process of speciation, whereby a single species evolves into two, but the forces that usually drive this process are controversial. Some propose that the evolution of reproductive isolation between species is driven by adaptation to differing habitats. Others propose that reproductive isolation evolves as a result of sexual selection driving continual change within species, resulting in incompatibilities when they come into contact. We will test these ideas by comparing patterns of trait divergence and reproductive isolation in a variety of species pairs in western Canada and central Siberia. Both regions were not forested during the Ice Ages. Now, each contains many contact zones between distinct western and eastern forms of birds that diverged in separate refugia. These contact zones provide a 'natural laboratory' for the study of how new species arise. Our goal is to study whether and how reproductive isolation is developing in multiple species pairs in these regions, and then to draw general conclusions regarding the factors that promote or hinder speciation. We will study geographic variation in genetics, songs, ecology, migratory behavior, and body shape and size with the goal of measuring reproductive isolation and its causes. In addition to helping resolve the relative importance of sexual and natural selection in speciation, these studies will examine the importance of (1) hybridization and (2) seasonal migratory behavior in speciation. To examine hybridization, we will compare three warbler hybrid zones and determine whether there are common parts of the genome under selection. We will also test whether the Audubon's warbler is the first known case of hybrid speciation in birds; preliminary data suggest it is. To examine seasonal migratory behavior, we will study variation in migratory behavior across a hybrid zone between two forms of Swainson's thrush; we hypothesize that the pure forms will have divergent migratory routes, while the hybrids will have intermediate routes and will suffer higher mortality. There are many migratory divides known in birds, and our study will be the first to directly test the idea that hybrids are selected against because of inferior migratory behaviors.

有大量的证据表明物种形成的过程，即一个物种进化成两个物种，但通常驱动这一过程的力量是有争议的。有些人认为，物种之间生殖隔离的进化是由对不同栖息地的适应驱动的。另一些人认为，生殖隔离是性选择推动物种内部不断变化的结果，导致它们接触时不相容。我们将通过比较加拿大西部和西伯利亚中部各种物种对的性状分歧和生殖隔离模式来测试这些想法。这两个地区在冰河时期都没有森林。现在，每一个都包含了许多不同的西方和东方鸟类之间的接触区，这些鸟类在不同的避难所中分道扬镳。这些接触区为研究新物种的产生提供了一个“天然实验室”。我们的目标是研究生殖隔离是否以及如何在这些地区的多个物种对发展，然后得出一般性的结论，促进或阻碍物种形成的因素。我们将研究遗传学，歌曲，生态学，迁徙行为，体型和大小的地理变异，以测量生殖隔离及其原因。除了帮助解决性选择和自然选择在物种形成中的相对重要性外，这些研究还将研究（1）杂交和（2）季节性迁移行为在物种形成中的重要性。为了研究杂交，我们将比较三个莺杂交区，并确定是否有共同的基因组部分选择。我们还将测试奥杜邦莺是否是第一个已知的鸟类杂交物种形成的案例;初步数据表明它是。为了研究季节性迁徙行为，我们将研究两种形式的斯温森画眉之间的混合区的迁徙行为的变化;我们假设纯形式将有不同的迁徙路线，而杂交种将有中间路线，并将遭受更高的死亡率。在鸟类中有许多已知的迁徙划分，我们的研究将是第一个直接测试杂交种是因为低劣的迁徙行为而被选择的想法。