Extreme elevational migration spurred cryptic speciation in giant hummingbirds.

Area of Science:

• Ecoevolutionary biology
• Biodiversity research
• Ornithology

Background:

• Species niche dynamics are crucial for biodiversity but difficult to study.
• Niche expansion can be driven by local adaptation or limited by physiological trade-offs.
• Evolutionary shifts in migratory behavior can broaden avian climatic niches.

Purpose of the Study:

• Investigate the ecoevolutionary drivers of niche breadth in the giant hummingbird (Patagona gigas).
• Determine the roles of migratory behavior, performance trade-offs, and genetic structure in maintaining its broad niche.
• Understand the evolutionary limits on niche breadth and the speciation process.

Main Methods:

• Utilized satellite and light-level geolocator tracking to study movement patterns.
• Analyzed respiratory traits and population genomics.
• Compared high-elevation resident populations with the giant hummingbird.

Main Results:

• Documented an >8,300-km loop migration in the giant hummingbird, including a significant high-altitude ascent.
• Observed deep genomic divergence and postzygotic barriers between the giant hummingbird and high-elevation resident populations.
• Identified a previously undiscovered species of large hummingbird coexisting with the giant hummingbird.

Conclusions:

• Extreme migratory behavior in the ancestral giant hummingbird facilitated niche expansion.
• This expansion led to speciation, resulting in distinct high-elevation resident populations and the giant hummingbird.
• The study reveals evolutionary limits on niche breadth and the role of extreme migration in driving speciation.