Extreme elevational migration spurred cryptic speciation in giant hummingbirds

• 成果类型: Article
• 署名作者: Williamson, Jessie L.; Gyllenhaal, Ethan F.; Bauernfeind, Selina M.; Bautista, Emil; Baumann, Matthew J.; Gadek, Chauncey R.; Marra, Peter P.; Ricote, Natalia; Valqui, Thomas; Bozinovic, Francisco; Singh, Nadia D.; Witt, Christopher C.
• 署名单位: University of New Mexico; University of New Mexico; Cornell University; Cornell University; United States Department of Energy (DOE); Los Alamos National Laboratory; Georgetown University; Universidad Adolfo Ibanez; Universidad Nacional Agraria La Molina; Pontificia Universidad Catolica de Chile; University of Oregon
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13049
• DOI: 10.1073/pnas.2313599121
• 发表日期: 2024-05-21
• 关键词: evolution; genome; performance; HISTORY; extinction; adaptation; alignment; package; format

摘要

The ecoevolutionary drivers of species niche expansion or contraction are critical for biodiversity but challenging to infer. Niche expansion may be promoted by local adaptation or constrained by physiological performance trade-offs. For birds, evolutionary shifts in migratory behavior permit the broadening of the climatic niche by expansion into varied, seasonal environments. Broader niches can be short-lived if diversifying selection and geography promote speciation and niche subdivision across climatic gradients. To illuminate niche breadth dynamics, we can ask how outlier species defy constraints. Of the 363 hummingbird species, the giant hummingbird (Patagona gigas) has the broadest climatic niche by a large margin. To test the roles of migratory behavior, performance trade-offs, and genetic structure in maintaining its exceptional niche breadth, we studied its movements, respiratory traits, and population genomics. Satellite and light-level geolocator tracks revealed an >8,300-km loop migration over the Central Andean Plateau. This migration included a 3-wk, similar to 4,100-m ascent punctuated by upward bursts and pauses, resembling the acclimatization routines of human mountain climbers, and accompanied by surging blood-hemoglobin concentrations. Extreme migration was accompanied by deep genomic divergence from high-elevation resident populations, with decisive postzygotic barriers to gene flow. The two forms occur side-by-side but differ almost imperceptibly in size, plumage, and respiratory traits. The high-elevation resident taxon is the world's largest hummingbird, a previously undiscovered species that we describe and name here. The giant hummingbirds demonstrate evolutionary limits on niche breadth: when the ancestral niche expanded due to evolution (or loss) of an extreme migratory behavior, speciation followed.