Bird “goes extinct” twice

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That’s how it is being reported. What seems to have really happened is that the white-throated rail of Madagascar colonized distant islands and lost the ability to fly. It died out about 136 kya when its island was submerged. Then the same thing was happening to a successor colony again at 100 kya; it went flightless.

From ScienceDaily:

This means that one species from Madagascar gave rise to two different species of flightless rail on Aldabra in the space of a few thousand years…
“Conditions were such on Aldabra, the most important being the absence of terrestrial predators and competing mammals, that a rail was able to evolve flightlessness independently on each occasion.” Paper. (paywall) – Julian P Hume, David Martill. Repeated evolution of flightlessness in Dryolimnas rails (Aves: Rallidae) after extinction and recolonization on Aldabra. Zoological Journal of the Linnean Society, 2019; DOI: 10.1093/zoolinnean/zlz018 More.

It’s called “iterative evolution,” in the sense that the same evolution happened a second time, and maybe will happen a third time.

Note that loss of the ability to fly is treated in this story as a form of evolution, as if the loss resulted in greater complexity rather than less. As if it wasn’t fatal when the island was inundated. But it enables evolutionary biologists to say that “evolution happened.”

Although observed in as sea cows, ammonites, and sea turtles, interactive evolution was not observed before in birds:

According to a study published Wednesday in the Zoological Journal of the Linnean Society, the rail is an example of a rarely observed phenomenon called iterative evolution, in which the same ancestral lineage produces parallel offshoot species at different points in time. This means that near-identical species can pop up multiple times in different eras and locations, even if past iterations have gone extinct.Becky Ferreira, “This Bird Went Extinct and Then Evolved Into Existence Again” at Motherboard

It would be far more interesting, actually, if the birds had acquired a new skill instead of losing an old one. Maybe there will turn out to be a genetic pathway that facilitates devolution like this.

See also: The doomsday extinction rhetoric ignores the speciation mess Without a clearly understood concept of “species”, it’s hard to know what extinction even means. If all individual life forms are unique, then every death is an extinction. Where do we draw the line and why, exactly?

and

Devolution: Getting back to the simple life

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Comments

“Conditions were such on Aldabra, the most important being the absence of terrestrial predators and competing mammals, that a rail was able to evolve flightlessness independently on each occasion.”
There's a phrase worth keeping: "was able to evolve flightnessness". The fact that they're serious about it makes it even funnier. Some satire seems appropriate … "The rail, at some point, evolved mechanisms and neurological pathways that made it capable of travelling through the air in what we call 'flight'. That was a bit of a challenge for evolution, but not really. It happens frequently. However, as a real example of the power of evolution to create amazingly transformative features, the rail actually evolved the ability of flightlessness. As long as the bird didn't need to soar into the air over the water to catch fish, into trees for seeds and nuts, across the landscape for insects or simply even just for the joy of flying, then evolution came up with an amazing solution: "just walking around", or more technically: "non-functional wings". And people actually think that mutations cannot create novel features in organisms."
Note that loss of the ability to fly is treated in this story as a form of evolution, as if the loss resulted in greater complexity rather than less. As if it wasn’t fatal when the island was inundated. But it enables evolutionary biologists to say that “evolution happened.”
Yes, it makes it sound like "flightlessness" is as great an evolutionary achievement as the supposed evolution of flight itself was.
It would be far more interesting, actually, if the birds had acquired a new skill instead of losing an old one.
Yes, for example, evolving even greater powers of flight.. But supposedly, as long as there are no predators around, the organism couldn't find any other uses for the ability to fly so it just chose to walk on the ground instead. Use it or lose it. They just lost interest in flying and then their wings stopped functioning.Silver Asiatic_{May 12, 2019
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