Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA; Department of Biology, University of Virginia, Charlottesville, VA, USA.
Museum of Natural Science and Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA.
Mol Phylogenet Evol. 2024 Aug;197:108111. doi: 10.1016/j.ympev.2024.108111. Epub 2024 May 25.
Swallows (Hirundinidae) are a globally distributed family of passerine birds that exhibit remarkable similarity in body shape but tremendous variation in plumage, sociality, nesting behavior, and migratory strategies. As a result, swallow species have become models for empirical behavioral ecology and evolutionary studies, and variation across the Hirundinidae presents an excellent opportunity for comparative analyses of trait evolution. Exploiting this potential requires a comprehensive and well-resolved phylogenetic tree of the family. To address this need, we estimated swallow phylogeny using genetic data from thousands of ultraconserved element (UCE) loci sampled from nearly all recognized swallow species. Maximum likelihood, coalescent-based, and Bayesian approaches yielded a well-resolved phylogenetic tree to the generic level, with minor disagreement among inferences at the species level, which likely reflect ongoing population genetic processes. The UCE data were particularly useful in helping to resolve deep nodes, which previously confounded phylogenetic reconstruction efforts. Divergence time estimates from the improved swallow tree support a Miocene origin of the family, roughly 13 million years ago, with subsequent diversification of major groups in the late Miocene and Pliocene. Our estimates of historical biogeography support the hypothesis that swallows originated in the Afrotropics and have subsequently expanded across the globe, with major in situ diversification in Africa and a secondary major radiation following colonization of the Neotropics. Initial examination of nesting and sociality indicates that the origin of mud nesting - a relatively rare nest construction phenotype in birds - was a major innovation coincident with the origin of a clade giving rise to over 40% of extant swallow diversity. In contrast, transitions between social and solitary nesting appear less important for explaining patterns of diversification among swallows.
燕子（燕科）是一种分布广泛的雀形目鸟类，它们在体型上非常相似，但在羽毛、社会性、筑巢行为和迁徙策略上却存在巨大的差异。因此，燕子物种已成为经验行为生态学和进化研究的模式，而燕科内部的变异为特征进化的比较分析提供了极好的机会。要利用这种潜力，就需要有一个全面且解析度高的该科的系统发育树。为了满足这一需求，我们利用从几乎所有公认的燕子物种中采样的数千个超保守元件（UCE）基因座的遗传数据来估计燕子的系统发育。最大似然法、合并法和贝叶斯法都得出了一个解析度高的到属水平的系统发育树，在种水平上的推断存在较小的分歧，这可能反映了正在进行的种群遗传过程。UCE 数据特别有助于解决深节点问题，这些问题以前一直困扰着系统发育重建工作。从改进的燕子树得出的分歧时间估计支持该家族起源于中新世，大约 1300 万年前，随后在中新世晚期和上新世主要群体发生多样化。我们对历史生物地理学的估计支持这样一种假说，即燕子起源于热带非洲，随后在全球范围内扩张，在非洲发生了主要的原地多样化，随后在热带美洲的殖民化过程中发生了次要的主要辐射。对筑巢和社会性的初步研究表明，泥巢筑造的起源——鸟类中一种相对罕见的巢建造表型——是一个主要的创新，与导致现存燕子多样性的 40%以上的进化枝起源同时发生。相比之下，社会性和独居性筑巢之间的转变对于解释燕子物种多样化模式似乎不太重要。
