Later On

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Evolution beyond adaptation

with 5 comments

Very intriguing article at Wired Science by Brandon Keim:

What explains the incredible variety of life on Earth? It seems obvious. Evolution, of course! But perhaps not the evolution most people grew up with.

Some ecologists say the theory needs an update. They’ve proposed a new dynamic driving the emergence of new species, one that doesn’t involve adaptations or survival of the fittest.

Give evolution enough time and space, they say, and new species can just happen. Speciation might not only be an evolutionary consequence of fitness differences and natural selection, but a property intrinsic to evolution, just as all matter has gravity.

“Our work shows that evolution wants to be diverse,” said Yaneer Bar-Yam, president of the New England Complex Systems Institute. “It’s enough for organisms to be spread out in space and time.”

In a March 13 Proceedings of the National Academy of Sciences paper, Bar-Yam and his co-authors, Brazilian ecologists Ayana Martins at the University of Sao Paulo and Marcus Aguiar at the University of Campinas, modeled the evolution of greenish warblers living around the Tibetan plateau.

The warblers are what’s known as a ring species, a rare phenomenon that occurs when species inhabit a horseshoe-shaped range. Genes flow around the ring, passing between neighboring populations — yet at the ring’s tips, the animals no longer interbreed with one another.

By the usual standards, these end populations have become new species. According to the researchers’ model of the process, no special adaptations or differences in reproductive fitness are needed to explain — or at least to computationally replicate — the greenish warblers’ divergence.

“This sounds kind of crazy, right? We normally think of species as being adapted for particular functions. They have their own role to play in a community. That’s the standard wisdom,” said theoretical ecologist James O’Dwyer of the Santa Fe Institute, who was not involved in the study.Instead, over 2,000 modeled generations, a time frame that fits with the 10,000 years that greenish warblers have ringed the Tibetan plateau’s slopes since their exposure by retreating glaciers, random genetic mutations drifted through the birds’ populations, ultimately clustering in diversity patterns resembling what’s seen in reality.

Adaptation and natural selection certainly played a part in the warblers’ evolution, said Bar-Yam, but they weren’t necessarily the driving forces. And though geography is involved, it’s very different from the population-isolating physical separation created by mountain ranges or islands. . .

Continue reading.

Written by Leisureguy

30 March 2013 at 10:06 am

Posted in Evolution, Science

5 Responses

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  1. Reblogged this on msamba.

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    agogo22

    30 March 2013 at 10:49 am

  2. I guess I don’t get the point of all this. Mutations just happen. They either adapt or are selected out. Those that succeed contribute to the observed diversity and variety which sometimes appears to be excessive and remarkable – but so what?

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    Bob Slaughter

    30 March 2013 at 12:35 pm

  3. I believe it’s the discovery that a new species can arise not from adaptation/natural selection but from genetic drift. That is, even if everything is completely adapted to its ecological niche, new species will arise anyway. One way to look at it is evolution favors increasing diversity, I suppose, but it also looks as though evolution is an unstable process.

    That is, if I understand it right, even though all the greenish warblers are in (essentially) the same environment, evolution proceeds anyway.

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    LeisureGuy

    30 March 2013 at 12:40 pm

  4. If it succeeds it has adapted by definition. I see nothing unique about it’s evolution – only that it has it’s place in the diverse mix of species observed.

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    Bob Slaughter

    30 March 2013 at 7:46 pm

  5. I see that this is just occurring like all evolution, it is just by chance that other species within the group have continued to survive along side newer species until the youngest ones are no longer able to interbreed

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    consciaspuella

    15 April 2013 at 5:43 pm


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