Is Evolution Predictable? Scientist Turns Over New Leaf In Theory

May 16, 2014

Scientists have long wondered if a species would evolve in the same way if you were to go back in time and start its evolution over; or if nature would take a different course the second time around.

A new study finds evolution can be predictable, if conditions are right.

Utah State University Assistant Professor of biology Zach Gompert had wondered this too. So, using walking stick insects that call different plants home, he set out to find an answer.

Gompert decided to look back in time at evolution’s path though ecotype stick insects, or insects that are in the gray area of being one species or two. The insects call two different plants home, meaning one ecotype looks more like a leafy shrub while the other looks a little more needly.

After netting the bugs, grinding them up and sequencing their genomes, Gompert discovered that around 80 percent of the changes that had occurred between the two ecotypes were pretty much random, but around 20 percent of the changes happened in the same genes across the ecotype populations.

“There is some sort of repeatable, deterministic component to speciation and evolution in general, right? Even though there is a lot of noise and a lot of the genome is doing different things in each of these cases, there is this sort of core percent of the genome that is doing the same thing again and again and again, suggesting that there is a predictable aspect to evolution.”

To confirm what the genes were telling him, Gompert ran a second experiment that would tell him if these same genes continued to be more susceptible to change when one ecotype, say the leafy looking stick, were transplanted to a needly environment.

“So, what we were able to do then is go out and collect stick insects from a single population and transplant them to the different host plant and then come back a generation later and sample all the offspring of those initial founders that we put out.”

Gompert found that after only one generation of living on a different plant, changes could be detected in the genome in the same places he had seen consistent differences in the natural population that had taken many generations to evolve.

He says the experiment shows that evolution is not necessarily a slow process and that if organisms are put under the same conditions, you’re likely to get a similar outcome in their evolution.

Gompert's research was published in Science on Friday.