The inversion can be a driver of speciation. In the process of gene-shuffling during the formation of sex cells (known as recombination), an inverted region can't successfully swap genes with its counterpart chromosome precisely because it's backwards. Lowry's first clue was that crosses between the two ecotypes didn't produce any recombinations in the part of the chromosome where the inversion was eventually found.
Because they aren't reshuffled by recombination, the genes within the inverted stretch end up traveling through time as one large block of genes, rather than an assortment. "So the inversion sort of works like a super gene," Lowry said.
Inversions are particularly interesting to biologists who are trying to figure out how one species becomes two. Notably, many significant inversions have been identified between humans and chimpanzees. And one of Lowry's Duke advisors, biologist Mohamed Noor, has found inversions help separate new species of fruitflies.
"Inversions are going to be seen as an important part of local adaptation as more people look for them," said Duke biology professor John Willis, who was Lowry's thesis advisor and co-author. "This is an extremely important argument and could explain a lot of the inversions that people are finding."
To prove the adaptations were in the inversions, Lowry painstakingly put the annual spelling of the inversion into perennial plants and the perennial spelling into the annuals through a long series of crosses in the greenhouses at Duke. Then he took 1,600 of these carefully edited plants out to test plots across several habitats in the Pacific Northwest to see how they'd do in the 2009 growing season. "It was a huge amount of
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