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A new study from Utah State University could help scientists forecast how and whether creatures can adapt to habitat shifts like climate change.
"As we change the landscape, change the environment, it would be nice to know how populations can evolve or not," said USU scientist Zachariah Gompert. "It seems like there are components that are predictable."
While chance has a large hand in genetic mutations, Gompert's new study of insect genomes published in the journal Science shows there are some repeatable patterns.
Gompert and his colleagues looked at two varieties of the same species of stick insects. One ecotype of the Timema cristianae bug has a black stripe down its back and the other is a different shade of green, adaptations that help the creatures blend into the specific plant species where they spend their entire lives in California's Santa Ynez Mountains.
"We have a population repeatedly adapting to some similar environment … either it takes the same route each time or it doesn't," he said. "Most people look at it in the context of a single trait or gene. Here, we're able to say, if we looked across the entire genome, is it doing the same thing if you expose it to the same environment?"
The scientists analyzed bug genomes looking for mutations in the same places. They found that separate populations of the insects adapted to the same plant had about 17 percent of their mutations in common, Gompert said.
"There's a significant portion of the genome that is showing these repeatable patterns," he said. The common mutations, meanwhile, seemed to be responsible for important adaptations.
The researchers then moved a population of the stick insects to a new plant, to see if they would evolve in predictable ways. When the researchers came back a generation later, they found divergences were about 1.5 times more likely to correlate with each other than be simply random.
"There's this core set of things that seem to be predictable from long-term patterns in nature and from our experiments," Gompert said, "and they seem to be important things."