EAGER: The impact of selection and temperate-tropical transitions on the evolution of New World bird diversity

生物多样性的许多基本模式已经被观察到，但解释这些模式被证明是具有挑战性的。特别是热带地区（赤道南北纬23.5°）比温带地区拥有更多的物种，其中许多热带物种在生理、行为和身体形态上都有显著的差异。其中一些差异被认为是物种数量的进化驱动因素；例如，雌性可以从许多竞争的雄性中选择的物种可能更容易分裂成多个物种，因为雌性的偏好可以迅速改变。要验证这一点和相关的假设，需要有难以量化的物种特征的综合数据库，包括社会群体规模和繁殖系统。这个项目将产生第一个公开可用的大规模数据集，其中包括一个衡量女性选择重要性的指标，男性睾丸大小。这些数据将被汇编成新大陆鸟类的大样本，并用于测试纬度、繁殖系统、社会系统和物种形成率之间的关系。理解这些关系是解释大范围多样性模式的基础，从而为保护规划和政策提供信息。该项目验证了一个假设，即温带-热带生物地理的转变影响了新世界雀形目鸟类的交配和社会系统的进化，最终这些行为特征反过来可能影响了多样化率。具体来说，这项工作将集中于基于博物馆标本数据的所有新世界电影的组合睾丸质量数据集的汇编，以一种关于繁殖纬度的无偏倚的方式进行统一分析。由于睾丸大小与精子竞争程度的相关性，这些数据可以用作繁殖系统的代理，以测试热带栖息地选择遗传一夫一妻制的假设，有利于社会性的进化（特别是合作繁殖）。新世界电影是解决这些问题的理想选择，因为它们种类繁多，在热带和温带之间多次过渡，在博物馆收藏中有很好的代表性，而且几乎所有的电影都被包括在物种级别的系统发育中（鹪鹩除外，该项目将为其产生第一个系统发育）。这些数据和分析将为更广泛地测试纬度、物种特征和新大陆鸟类多样化率之间的关系奠定基础。

Many fundamental patterns of biological diversity have been observed, but explaining these patterns has proven challenging. In particular, the tropics (the area ~23.5° north and south of the equator) harbor many more species than the temperate zones, and many of these tropical species are significantly differentiated in their physiology, behavior, and body morphology. Some of these differences have been proposed as evolutionary drivers of species numbers; for instance, species in which females can choose from many competing males may fragment into multiple species more easily as female preferences can quickly change. Testing this and related hypotheses requires comprehensive databases of hard-to-quantify species characteristics, including social group sizes and breeding system. This project will produce the first publicly available large-scale data set that includes a metric of the importance of female choice, male testis size. These data will be compiled for a large sample of New World birds, and used to test for relationships among latitude, breeding system, social system, and the rate of speciation. Understanding these relationships is fundamental to explaining broad-scale diversity patterns, which informs conservation planning and policy.This project tests the hypothesis that temperate-tropical biogeographic transitions affect the evolution of mating and social systems in New World oscine passerine birds, and ultimately that these behavioral characteristics in turn may have affected diversification rates. Specifically, this work will focus on compilation of a data set of combined testis mass for all New World oscines based on museum specimen data, uniformly analyzed in a fashion unbiased with regard to breeding latitude. Due to the correlation of testis size with the degree of sperm competition, these data can be used as a proxy for breeding system, to test the hypothesis that tropical habitats select for genetic monogamy, favoring the evolution of sociality (in particular, cooperative breeding). New World oscines are ideal for addressing these issues as they are diverse, have transitioned between the tropics and temperate zone many times, are well-represented in museum collections, and nearly all have been included in species-level phylogenies (with the exception of wrens, for which this project will generate the first phylogeny). These data and analyses will form the basis for broader tests of the relationship among latitude, species traits, and diversification rates in New World birds.