Ecology and evolution of young species in sympatry

生物多样性在世界各地和加拿大有着巨大的差异，并为加拿大人提供了重要的功能和服务。当一个物种的种群彼此分离，通常处于地理隔离状态（异种），并最终恢复到二次接触和重叠状态（同族），从而增加了当地和区域的生物多样性，生物多样性就形成了。我们研究的重点是次级共生——年轻的物种如何生活在一起，它们如何影响彼此的生态和进化？这些问题的答案很重要——如果我们要保护生物多样性，我们必须了解生物多样性是如何形成和维持的。本研究的具体目的是测试幼种间的次生接触和同族关系对(I)物种识别和（II）生态学特征的影响。我们用鸟类来解决这些问题，因为鸟类的分布、分类和进化关系比任何其他群体都更为人所知。(1)物种识别特征——我们之前的研究表明，当密切相关的鸟类生活在同栖环境中时，它们在物种识别（颜色图案和鸣叫）方面的特征差异更大。我们建议通过比较研究和实验研究来检验不同的假设来解释这种模式（杂交、侵略、信号干扰、通过生态性状进行的间接选择）。（II）生态特征——我们之前对幼雏物种的生态学研究表明，近亲鸟类最初使用相似的栖息地和重叠的繁殖区域，然后在栖息地的使用上出现分歧。我们将测试特征位移假说来解释栖息地差异，使用实验来检查适应成本和选择压力作用于一对共同生活的年轻物种，代表三个不同的鸣禽科。总之，我们的研究将测试生物多样性形成过程中年轻物种之间相互作用的重要性，为密切相关的物种如何以及多久影响彼此的生态和进化提供重要见解，更广泛地说，密切相关的物种之间的相互作用如何促进或限制当地的生物多样性。

Biodiversity varies dramatically across the world and Canada, and performs important functions and services for Canadians. Biodiversity forms when populations of one species diverge from one another, typically in geographic isolation (allopatry), and eventually come back into secondary contact and overlap (sympatry), augmenting local and regional biodiversity. The focus of our research is secondary sympatry - how do young species live together, and how do they influence each other's ecology and evolution? An answer to these questions is important - we must understand how biodiversity forms and is maintained if we are to protect it. The specific objective of the proposed research is to test the consequences of secondary contact and sympatry among young species for traits involved in (I) species recognition and (II) ecology. We use birds to address these questions because the distribution, taxonomy, and evolutionary relationships of birds are better known than any other group. (I) Species Recognition Traits - Our previous work documented greater divergence in traits involved in species recognition (colour patterns and songs) when closely related species of birds live in sympatry. We propose to test among alternative hypotheses to explain this pattern (hybridization, aggression, signal interference, indirect selection through ecological traits) using comparative and experimental studies. (II) Ecological Traits - Our previous work on the ecology of young species suggests that closely related birds initially use similar habitats and overlap breeding territories, and then subsequently diverge in habitat use. We will test the Character Displacement Hypothesis to explain habitat divergence, using experiments to examine fitness costs and selective pressures acting on pairs of young species that live together, representing three distinct families of songbirds. Together, our research will test the importance of interactions among young species during the formation of biodiversity, providing important insights into how and how often closely related species influence each others' ecology and evolution, and, more broadly, how interactions among closely related species promote or constrain local biodiversity.