Bacterial Competition In Lab Shows Evolution Never Stops
Evolution is relentless process that seems to keep going and going, even when creatures live in a stable, unchanging world.
That's the latest surprise from a unique experiment that's been underway for more than a quarter-century.
Evolution is so important for biology, medicine and a general understanding of our world that scientists want to understand it as fully as possible. That's why, in 1988, biologist Richard Lenski took a dozen glass flasks and added identical bacteria to each of them. Those 12 populations have been evolving ever since, letting scientists watch evolution in real time.
Day after day — including holidays and weekends — workers in Lenski's lab at Michigan State University in East Lansing feed and care for the E. coli bacteria. The bacteria eat and divide again and again. The original microbes have produced more than 50,000 generations over the last 25 years.
Random mutations have allowed them to get fitter, meaning they reproduce faster. "In evolutionary biology, fitness is this representation of the ability of an organism to survive and reproduce," says Lenski. He explains that all else being equal, organisms that reproduce more quickly will have an advantage when competing with those that reproduce more slowly.
Early on, Lenski predicted his bacteria would adapt and adapt but eventually hit a wall — that they would reach a peak level of fitness they couldn't improve on.
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http://www.npr.org/blogs/health/2013/11/15/245168252/bacterial-competition-in-lab-shows-evolution-never-stops
= new reply since forum marked as read
1) thinking of their environment as unchanging is wrong, because the bacteria themselves are part of their own environment. Organisms deform their own fitness landscapes whenever they change, in a way that is kind of analogous to a mass deforming the spacetime it resides in.
2) when he says the rate of fitness increase is slowing down, I wonder if it's something like this, where fitness can increase continuously, but rate doesn't just slow down, it slows down toward an asymptote. You can increase forever, but still be up against a wall.
