"It's like a smoking gun," Ungerer said. "It helps us study the process."
The researchers now want to know the triggers of these proliferation events and how the species have reacted to this increase in genome size. Ungerer has received $610,000 from the National Science Foundation to study these rapid proliferation events and how they affect the evolution of the hybrid sunflowers.
"Although virtually all plants and animals have these types of sequences in their genomes, we still know very little about what phenomena cause them to amplify and make extra copies of themselves," Ungerer said.
Ungerer is studying two naturally occurring phenomena -- hybridization and stress -- that are hypothesized to cause proliferation of these mobile DNA sequences. The group of five annual sunflowers provides an excellent system to study the roles of hybridization and stress because not only have the three hybrid species arisen from ancient hybridization events, but they also are locally adapted to harsh and stressful environments, unlike their parental species. Two of the hybrid species grow in the desert and the third hybrid species grows in salt marshes, Ungerer said.
Ungerer's second project looks at clinal variation of a perennial sunflower species. This species has a wide geographic distribution across central North America and grows in areas from Texas north to Manitoba, Canada. Ungerer wants to understand population differences between sunflowers in different parts of the region.
For this research, Ungerer's team is conducting common garden experiments, which involve gathering seeds from each of the populations across central North America. The Kansas seeds came from the Konza Prairie Biological Station. The seeds are then grown in the same common garden at Kansas State University.
"If you see differences among plants in a common garden experiment, you attribute that to genetic
|Contact: Mark Ungerer|
Kansas State University