Evolution in the Lab -- Again

This should drive the creationists crazy. Check out this item at PhysOrg: How predictable is evolution? They say, with bold font added by us:

Understanding how and why diversification occurs is important for understanding why there are so many species on Earth. In a new study published on 19 February in the open access journal PLOS Biology, researchers show that similar — or even identical — mutations can occur during diversification in completely separate populations of E. coli evolving in different environments over more than 1000 generations. Evolution, therefore, can be surprisingly predictable.

The paper they’re reporting about is Parallel Evolutionary Dynamics of Adaptive Diversification in Escherichia coli. You can read it online without a subscription. Okay, back to PhysOrg:

The experiment, conducted by Matthew Herron, research assistant professor at the University of Montana, and Professor Michael Doebeli of the University of British Columbia, involved 3 different populations of bacteria. At the start of the experiment, each population consisted of generalists competing for two different sources of dietary carbon (glucose and acetate), but after 1200 generations they had evolved into two coexisting types each with a specialized physiology adapted to one of the carbon sources.

That sounds like a lot of generations, and it is, but under proper conditions E. coli can reproduce 2 or 3 times per hour. That’s at least 50 generations per day, so the whole 1,200 generation experiment could have been conducted in less than a month. In contrast, that many human generations (each only 20 years) would require 24,000 years — far longer than the span of written human history. In all that time, we’ve developed some lactose tolerance, and perhaps some immunity to bubonic plague, but other than maybe hair loss and dental problems, not much else. Try to explain to the creationists why no one has literally seen a monkey evolve into a man. Okay, back to PhysOrg:

Herron and Doebeli were able to sequence the genomes of populations of bacteria frozen at 16 different points during their evolution, and discovered a surprising amount of similarity in their evolution.

We can already hear the Discoveroids: The experiment was conducted in a lab. It was designed! Whatever they found is evidence of intelligent design! Yeah, right. Let’s read on:

“In all three populations it seems to be more or less the same core set of genes that are causing the two phenotypes that we see,” Herron said. “In a few cases, it’s even the exact same genetic change.”

[...]

“There are about 4.5 million nucleotides in the E. coli genome,” he said. “Finding in four cases that the exact same change had happened independently in different populations was intriguing.”

Jeepers. What are the odds of that? It’s gotta be the intelligent designer, doesn’t it? We continue:

Herron and Doebeli argue that a particular form of selection — negative frequency dependence — plays an important role in driving diversification. When bacteria are either glucose specialists or acetate specialists, a higher density of one type will mean fewer resources for that type, so bacteria specializing on the alternative resource will be at an advantage. “We think it’s likely that some kind of negative frequency dependence — some kind of rare type advantage — is important in many cases of diversification, especially when there’s no geographic isolation,” Herron said.

“Negative frequency dependence”? Not intelligent design? How disappointing for the creationists. Well, they can deal with this. After all, it’s only micro-evolution. They’re still E. coli. They didn’t get a crock-o-duck. Okay, that’s it for PhysOrg. Here’s the last part of the paper’s abstract:

This process closely corresponds to the evolutionary dynamics seen in mathematical models of adaptive diversification due to frequency-dependent ecological interactions. The parallel genetic changes underlying similar phenotypes in independently evolved lineages provide empirical evidence of adaptive diversification as a predictable evolutionary process.

Very nice. Favorable genetic adaptations — new information! — occurred in the lab, all tidily documented, and sometimes it was the exact same adaptation. To the astonishment of creationists, no supernatural interference seems to have been necessary. All it took was a little more than a thousand microbial generations and less than 30 days. Imagine what might have happened during the so-called Cambrian explosion, which lasted about 50 million years.

Copyright © 2013. The Sensuous Curmudgeon. All rights reserved.

• • • • • • • • • • •

. . Permalink for this article