Research published in Evolution analyzed feathers and body structures of flightless birds and their closest flying relatives.
Aim: To determine which traits change first when birds evolve to be flightless.
Why Birds Lose Flight
Island Effect:
Birds on predator-free islands adapt to ground living and gradually lose flight-related traits.
Semi-Aquatic Adaptation:
Birds like penguins lose flight but develop adaptations for underwater swimming.
Evolutionary Timeline
Flightless birds evolved from ancestors that once could fly.
Older Flightless Species:
Example: Ostriches lost flight long ago, leading to drastic feather changes (long, shaggy feathers).
Recently Flightless Species:
Example: Fuegian steamer duck lost flight recently, so its feathers remain similar to flying relatives.
Key Takeaways
Skeleton & feathers change at different rates after birds lose flight.
Long-term flightlessness (e.g., ostriches) leads to major feather modifications.
Recent loss of flight (e.g., Fuegian steamer) results in minimal feather changes.
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