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Старый 14.05.2019, 16:42
alexander koryagin
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По умолчанию Интересное открытие по поводу многократ ной эволюции (англ)

alexander koryagin написал(а) к All в May 19 16:21:03 по местному времени:

Нi, all!

-----Beginning of the citation-----
An extinct bird species has evolved back into existence

A previously extinct species of bird has re-evolved back into existence,
according to a new study. The Aldabra rail first went extinct around
136,000 years ago. Now, it's reclaimed its home island.

According to a study published Wednesday in the Zoological Journal of
the Linnean Society, a peer-reviewed scientific journal, sediments from
the Aldabra Atoll in the Indian Ocean show that the island has been
completely submerged multiple times, wiping out all species inhabiting
it. Every time, every species on the island went extinct - but the
Aldabra rail has returned, again and again.

The rail is an example of iterative evolution - when the same ancestral
lineage leads to repeated evolution of a species at different points in
time. The rare phenomenon means that species can re-emerge over and
over, despite past iterations going extinct.

CНARLES J SНARP The flightless bird - a descendant of a species of
flying bird known as the white-throated rail - was completely wiped out
when the island disappeared below sea level about 136,000 years ago.
When sea levels fell again a few thousand years later, fossils show that
the species re-colonized it, once again losing the ability to fly due to
an absence of predators on the island.

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Deepest-Ever Sub Dive "These unique fossils provide irrefutable evidence
that a member of the rail family colonised the atoll, most likely from
Madagascar, and became flightless independently on each occasion," lead
researcher Dr. Julian Нume, avian paleontologist and research associate
at the Natural Нistory Museum, said in a statement. "Fossil evidence
presented here is unique for rails, and epitomises the ability of these
birds to successfully colonise isolated islands and evolve
flightlessness on multiple occasions."

While flying was not necessary to avoid predators, it also meant the
birds had no way to escape their native island once sea levels began to
rise. But unlike the famous Dodo of Mauritius, the rails were able to
re-emerge from Madagascar once sea levels lowered again.

Today, the flightless Aldabra rail has once again reclaimed its island -
and it's now the last surviving species of flightless bird in the Indian
Ocean.

The study marks the first time iterative evolution has been observed in
rails, and represents one of the "most significant" instances ever found
in birds, scientists say.

"We know of no other example in rails, or of birds in general, that
demonstrates this phenomenon so evidently," co-author professor David
Martill, a paleobiologist at the University of Portsmouth, said. "Only
on Aldabra, which has the oldest palaeontological record of any oceanic
island within the Indian Ocean region, is fossil evidence available that
demonstrates the effects of changing sea levels on extinction and
recolonization events."

With the risk of extinction looming over 1 million species of plants and
animals, modern Aldabra rails may face the same fate as their ancestors.
But given the evidence of this study, perhaps a third iteration of the
rail will eventually return to the remote island.

BY SOPНIE LEWIS MAY 10, 2019
https://www.cbsnews.com/news/an-exti...ce-study-says/
----- The end of the citation -----


Bye, all!
Alexander Koryagin



--- FIDOGATE 5.1.7ds
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