Evolution is as complicated as 1-2-3

[Keeper]

EAST LANSING, Mich. — A team of researchers at Michigan State University has documented the step-by-step process in which organisms evolve new functions.

The results, published in the current issue of Nature, are revealed through an in-depth, genomics-based analysis that decodes how E. coli bacteria figured out how to supplement a traditional diet of glucose with an extra course of citrate.

read the full article here:
http://news.msu.edu/story/evolution-is-as-complicated-as-1-2-3/


what I found particularly interesting was this:

“We first saw the citrate-using bacteria around 33,000 generations,” Lenski explained. “But Zack was able to show that some of the important mutations had already occurred before then by replaying evolution from different intermediate stages. He showed you could re-evolve the citrate-eaters, but only after some of the other pieces of the puzzle were in place.”

Does this mean creatures are "always" bound to evolve certain features?

 

[Techne]

Not "always". Potentially. As the article says:

The first stage was potentiation, when the E. coli accumulated at least two mutations that set the stage for later events. The second step, actualization, is when the bacteria first began eating citrate, but only just barely nibbling at it. The final stage, refinement, involved mutations that greatly improved the initially weak function. This allowed the citrate eaters to wolf down their new food source and to become dominant in the population.

So once a few "potentiating" mutations occur, the potential exists that they will acquire the citrate metabolizing adaptation. This of course does not imply it will be actualized.

I remember this study from some time ago. This is another related study:
Most Extensive Pictures Ever of an Organism's DNA Mutation Processes

Interesting stuff.

Also check out convergent evolution. A somewhat related phenomenon whereby very similar traits emerged in completely different organisms.