Biologist honored for illuminating evolutionary mystery
Aug 26, 2016 | Atlanta, GA
Will Ratcliff is having a moment in the spotlight for getting yeast and algae to jump through hoops to new evolutionary heights.
The magazine Popular Science has heaved the researcher from the Georgia Institute of Technology into its annual list “The Brilliant 10,” a select roster of “the 10 most innovative young minds in science and technology.” Ratcliff was praised for advancing the study of cellular evolution.
PopSci cited his work demonstrating how single-cell organisms may have transitioned into simple multicellular organisms ages ago. It’s widely seen as an arduous evolutionary leap, since single cells had to forfeit a lot of their own fitness for the greater good of creating viable cell groups.
“William Ratcliff revealed surprising insights into what might have been necessary for this transition to occur,” Popular Science wrote in its September/October edition. He has illuminated “one of the greatest mysteries of life.”
The needs of the many
Ratcliff, an assistant professor in Georgia Tech's School of Biological Sciences, has put thousands of generations of yeast and many generations of algae cells through stresses in the lab devised to get them to evolve better survival strategies around forming cohesive groups.
“We’re figuring out kind of clever ways to get them to form groups and then for those groups to become more complex,” he said.
The idea is to end up with a rudimentary multicellular being with cells taking on specialized roles, a very early step on the pathway to organ development. But the first advantage to group formation is simple -- size. Bigger is often better.
“A lot of small predators have small mouths that are great at eating single-cells,” Ratcliff said. But big multicellular cell clusters are too big for these predators to get their mouths around. Clustered cells survive to pass on their genes.
Race to the bottom
To accelerate the evolution of yeast from individuals cells into cell groups called “snowflakes,” one of his signature achievements, Ratcliff has selected for yeast cells that sink more quickly. There, again, big clusters sink better than single cells.
Once clusters are done outcompeting the unicells, they compete against each other. “It’s remarkable how quickly snowflake yeast clusters evolve new traits that let them win this race,” he said.
While the group gains various strengths, it sacrifices the viability of individual cells. “They evolve a division of labor in the group, in which some of them commit suicide,” Ratcliff said. That changes reproductive patterns, which makes the clusters’ progeny more competitive.
The loss of individual cell fitness is extensive.
The more robust a cluster gets, the less likely its individuals are to survive if they are caused to revert back to individual cells. It’s like an odd twist on the traditional marriage vows: Part, and you will die.
Much of Ratcliff’s research is funded by NASA’s Exobiology program and the National Science Foundation.
Felt it coming
Before Popular Science called for an interview for its four-paragraph nod, Ratcliff had sensed something was coming. For a few months, while the magazine cemented its list, it asked around at scientific societies about noteworthy up-and-coming researchers.
As a result, Ratcliff received some veiled tips.
“A couple of colleagues of mine said, ‘Hey man, I got a call from a reporter. I can’t tell you anything about it, but you may be hearing something soon,’” he said.
When PopSci called, a reporter told Ratcliff that many scientists had mentioned him, strongly influencing the decision to name him one of "The Brilliant 10." “That was very touching that people within the research community said to them they should look at my lab,” Ratcliff said.
Hail Mary pass
Life’s small coincidences have helped guide Ratcliff’s academic strivings down the path of evolutionary research.
His career in biology spawned from childhood, when his parents carted him and his brother Felix off in their summers to woodland family cabins next to craggy Pacific Coast cliffs near Mendocino, California. “There was really nothing to do except to run around the forest and the ocean checking out the lives of plants and animals,” Ratcliff said.
They got hooked; both brothers became biologists.
Plants became Ratcliff’s passion at an early age, which led to a bachelor of science in plant biology from the University of California, Davis, but that threw his career a serendipitous curve. “I thought it would have a lot to do with ecology, but it turned out to be mostly cellular biology.”
The decision to see if yeast cells could be coaxed into making the leap to multicellularity was also slightly capricious. “There was a lot of doubt surrounding it, but I thought, ‘Why not just give it a try and see,’" said Ratcliff, whose Ph.D. is in ecology.
He was astonished when that longshot worked. “It was a kind of Hail Mary pass,” he said. It led to a dedicated research specialization and a notable body of continuing work.