"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.
"In one of our experiments we were able to see five independent population expansions. We had one adaptive mutation that allowed a population to expand, but before it was able to completely take over another un-mutated population of the same cells acquired a different mutation that allowed it to succeed and impede the expansion of the first population."
In addition to determining if and when a population acquired an adaptation, Kao also identified the specific adaptations that were acquired. She accomplished this using a DNA-based technology that enabled her to determine the specific locations on the genes of the yeast cells that expressed beneficial adaptations.
What she found was that as populations rise and fall, some of these beneficial adaptations factor into the continued evolution of the organism; others don't.
"Due to the possibility of this competition, beneficial mutations that have been lost during the evolution of an organism will not be identified from just the final generation of that organism," Kao explained. "Indeed, we found that several of the mutations were nearly lost in the population by the end of the experiment due to this competition."
In other words, as Mother Nature sorts things out, some adaptations go by the wayside, with the latest generation of an organism sometimes showing no traces of them.
"Think of this as another piece of the evolution puzzle," Kao said. "We're gaining a comprehensive understandin
|Contact: Katy Kao|
Texas A&M University