image: Cape Sugarbird (Promerops afer) perched atop a Protea (also known as a sugarbush) along the coast of the Western Cape, South Africa. view more
Credit: Daniel J. Field
A study reconstructs the history of passerine bird diversification. Passerines, or perching birds, comprise more than 6,000 extant species and represent 60% of bird diversity. How Earth's history influenced the evolution of passerine diversity remains poorly understood. Carl Oliveros, Brant Faircloth, and colleagues constructed a comprehensive passerine evolutionary tree based on DNA sequence data from representatives of all 137 passerine families, including the extinct Hawaiian honeyeaters. The resulting tree clarified the relationships among the major passerine groups. After calibrating the timing of divergence between the various groups using 13 fossils of passerines and closely related birds, the authors estimated that passerines began to diverge in the Middle Eocene, approximately 47 million years ago. Models of biogeographic dispersal suggested that passerines originated in the Australo-Pacific region. The reconstructed evolutionary history reflects the influence of major climatic events, such as a period of extinction followed by rapid diversification during the Oligocene glaciation. The rate of diversification fluctuated throughout the Cenozoic Era but did not exhibit a strong correlation with global temperatures, in contrast to observations for modern birds. Nor were shifts in the diversification rate associated with the colonization of new continents. The results reconcile passerine evolutionary history with the fossil and geologic records and suggest that complex mechanisms drove diversification, according to the authors.
Article #18-13206: "Earth history and the passerine superradiation," by Carl H. Oliveros et al.
MEDIA CONTACT: Brant C. Faircloth, Louisiana State University, Baton Rouge, LA; tel: 225-578-1006; e-mail: brant@faircloth-lab.org
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Journal
Proceedings of the National Academy of Sciences