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Researchers Find Whole Genome Duplication Has Occurred Many Times during Evolution of Insects
Genome duplication – known scientifically as polyploidy – has long been known from plants. Theodosius Dobzhansky, an influential evolutionary biologist, observed in 1937 that the biggest difference between the evolution of plants and animals was polyploidy. In fact, many of the plants humans eat, such as broccoli, rice, corn and wheat, have experienced polyploidy during their evolution (sometimes called "paleopolyploidy"). But until now, scientists had limited evidence for this in animals.
A team of researchers headed by Assistant Professor Rebecca Rundell of ESF and Michael Barker of the University of Arizona has uncovered evidence for paleopolyploidy in the most diverse animals on Earth—the insects. The team's work was published online April 19 in the prestigious journal, Proceedings of the National Academy of Sciences. It will be featured on the journal's cover May 1.
Research team members created their own bioinformatics program to measure and characterize gene duplications in the insects, just as they do in plants. They found evidence of 18 "whole genome duplications" and at least six other "bursts" of gene duplication that occurred during the evolution of insects. This was extraordinary, considering that most of our past knowledge of such ancient whole genome duplication comes from plants. But the researchers decided it would be worth investigating animals further.
"Although ancient polyploidy has been found in fishes, our evidence for it in other clades of animals is limited to nonexistent," Rundell said. (A clade is a group of organisms that have evolved from a common ancestor.) "This is perplexing, considering the explosive diversification we sometimes see after paleopolyploidization events in plants. We might expect to see the same thing in hyperdiverse animals, too."
"[We] found the same genomic signatures of polyploidy in insects that we have observed in many plants. In the historical context of work on polyploidy, even from the plant perspective, this was shocking," said Barker, an assistant professor at UA.
In addition to Rundell and Barker, the research team included undergraduates studying bioinformatics with the Barker lab group, and graduate student lead authors Zheng Li of UA and George Tiley of the University of Florida and Duke University.
"One of the most thrilling aspects of this research is that it opens up entirely new areas of scientific exploration," said Rundell. "This is starting to re-write the book on what we think we know about how some of the most diverse animals evolved."
— This story is based on a news release issued by the University of Arizona.