A recent study has shown that the elephant bird of Madagascar is the closest relative of New Zealand's kiwi bird. This contradicts the theory that flightless birds arose when common ancestors drifted apart on land masses. The land mass theory was also disproven when DNA was sampled from the bones of the extinct moa and found the moa and the kiwi to not be closely related when the land mass theory hypothesized that they would be. Kiwi's were also found to be closely related to cassowaries and emus. Because both of these findings disprove the land mass theory, the researchers concluded that distant ancestors must have been able to fly.
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Article: https://www.sciencenews.org/article/flightless-birds%E2%80%99-history-upset-ancient-dna?mode=topic&context=76
I thought that the ability to fly would be an advantage, why then would these birds lose this ability over time? If it were the most fit passed on their genes, the flying bird should have been able to get away from more predators than the bird stuck on the forest floor. What could have cause these birds to lose their ability to fly once they reached the location they live in today?
ReplyDeleteKiwi's lay unusually large eggs and have few natural predators. The few predators would cause them to be able to survive not flying. The larger egg would make it very nearly impossible to fly. The lack of flight survived them well.
DeleteIt is definitely possible for kiwis to lose the ability to fly because there is more than one trait that is beneficial in an environment. Like we learned in the Barbellus assignment, species can take different evolutionary paths. A species with legs can evolve into a species with fins or even a species that burrows in the ground and the two resulting species will share a common ancestor. This is why a flying bird could potentially evolve into a flightless bird.
DeleteThe ability to fly may be an advantage, but for some birds it may not be found as useful in some environments. I think this connects to what we learning in class about evolution, sometimes when a certain body part is not used, it may go away because it is useless and the bird can survive without it.
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