Buttle's World

20 January, 2009

Fascinating Glimpse into Evolution

Filed under: Posts — clgood @ 9:25

At Texas A&M they’ve been able to watch evolution in action and, as usual, nature had some surprises for them.

It’s the first direct experimental evidence of this phenomenon in eukaryotic cells, or cells with nuclei, and it contrasts the widely accepted classical model of evolution, which doesn’t account for simultaneously developing beneficial adaptations, she said. Instead, that model adopts a linear approach, theorizing that a population acquires such adaptations successively, one after another. Rather than a competition occurring, the model posits a complete replacement of one generation by another better-adapted generation.

That wasn’t the case in Kao’s sample.

Observing the color-coded yeast populations as they evolved to respond to their environment, Kao saw some colors expand while others contracted – a sign that adaptations were occurring. But rather than one segment of the population continuing to shrink until it was completely replaced, some segments were able to compete long enough to acquire further adaptations. When this happened, Kao explained, these populations of cells – once apparently less-fit – began to swell while once-dominant populations started to shrink. This constant reduction and burgeoning of populations signaled the development of multiple beneficial adaptations and a subsequent competition by the cells that acquired them, Kao said.

“Essentially, we were watching evolution in action,” Kao said. “We’re watching evolution in real time. We’re actually seeing a mutation that shows these things have adapted and seeing their population thrive and expand from this adaptation. This is how evolution works.

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