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The question of the day : “Is it possible for an animal species to disappear and then re-evolve in the same way?”
Julien Jegues’ response:
Let’s be clear, a species that disappears can never reappear. But nothing prevents a close species from following, in a way, the same evolutionary path. The two would then be visually similar, but genetically different.
Let me introduce you to iterative evolution, a natural process of disextinction. If you have been attentive, you suspect that there is a socket. In reality, the exact definition would rather be “morphological evolutionary convergence”, evolutionary convergence being the development of similar characters in species that are nevertheless very distant. Example: wings in birds and bats.
Iterative evolution thus describes the process by which a species X goes qualified in a species Y in a practically identical way from the phenotypic point of view (that is to say the observable characters). Here is a small example.
The Aldabra rattle (Dryolimnas cuvieri aldabranus), flightless, died out before evolution reproduced a similar animal 36,000 years later: Cuvier’s rail (Dryolimnas cuvieri cuvierilisten)), also flightless and the last surviving species of the genus Dryolimnas. But how and why?
Some 36,000 years after the extinction of the Aldabra rail, evolution reproduced a similar animal: Cuvier’s rail. | desert naturalist via Wikimedia Commons
Aldabra is an atoll that found itself completely submerged 136,000 years ago, causing all of its terrestrial biodiversity to disappear. But more than 100,000 years ago, the Earth faced an ice age which produced a retreat of the waters.
As the sea level fell, the Aldabra atoll emerged and flying Dryolimnas recolonized the ecosystem. Then, the local environmental conditions being very close to those of 136,000 years ago, the species finally converged on a new flightless subspecies. A kind of natural revolution.
More commonly, they are characters that will appear repeatedly over evolutionary time, rather than an entire subspecies. Here are some examples of revolution:
- The passage in the marine environment in plants: seagrasses are flowering plants genetically analogous to those on land, but whose ancestors returned to salt water nearly 100 million years ago.
- Limbs in skinks: about 41 species of skinks in the genus Brachymeles (legless lizards), 17 underwent evolutionary reversal and regained their legs.
- Teeth in anurans: frogs would have lost their teeth more than twenty times and could be found six more times during their evolutionary history.
We can also mention the udders in mammals, oviparity and viviparity in reptiles, wings in insects, herbivory in Crocodyliformes of the Mesozoic – they would have passed through the vegetable diet at least three times during the ‘evolution-, etc.