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.
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?
Devolution: Getting back to the simple life
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