Whole-genome duplication drives long-term adaptation

Sometimes, the most important scientific discovery occurs from accident. Scientists have long known that the whole-tweenome duplication (WGD)-process by which organisms mimic all their genetic material-make an important role in development. But to understand how WGD arises, persists, and drive adaptation is poorly understood.

In an unexpected turn, the scientists of Georgia Tech not only revealed how WGD is, but also how it remains stable for thousands of generations of development in the laboratory.

The new study was led by William Rachliff, Professor in School of Biological Sciences, and Kai Tong, a former PhD. In Ratcliffe’s lab, a student who is now a postdorel fello at Boston University.

His paper, “Genome duplication in a long-term multiculture development experiment,” Published In Nature In March as a cover story of the journal.

“We determine to find out how the organisms infection for multiculturality, but the discovery of the role of WGD in this process was completely serious,” Ratcliffe said. “This research provides new insight on how WGD can emerge, continue longer, and fuel evolutionary innovation. It is really exciting.”

A secret hidden in data

In 2018, Ratcliffe’s lab began an experiment to detect open-ended multicolular evolution. Multicellular long -term growth experiment (multi) uses “snowflake” yeast as a medium, develops it in rapidly complex multicellular organisms from a single cell. Researchers do this by selecting yeast cells for large size on daily basis.

“These long -term development studies help us answer big questions how creatures adapt and develop.” “They often reveal unexpected and expand our understanding of evolutionary processes.”

This is exactly when a research faculty member at Rachlif’s lab saw something unusual in snowflake yeast. Bozdag observed the yeast when it was 1,000 days old and suggested that it may have gone from duality (two sets of chromosomes) to tetraploid (having four).

Decades of lab experiments suggest that tetraploid is characteristically unstable, withdrawing the duality within a few hundred generations. For this reason, Tong suspected that WGD had occurred and had lived in multiple generations in multi. If true, this will be the first time when a WGD spontaneously arises and remains in the laboratory.

After taking measuring the developed yeast, Tong found that he duplicated his genome long before – within the first 50 days of multi. Striking, these tetraploid genomes persisted for more than 1,000 days, with laboratory conditions, despite the normal instability of WGD.

The team found that the WGD arose and stuck all around as it gave the yeast an immediate benefit in growing large, long cells and creating large multicellular clusters, which are favored by size selection in multi.

Further experiments showed that while the WGD in the snowflake yeast is normally unstable, it remained in multi because large, multicellular groups had the advantage of survival. This stability allowed the yeast to undergo genetic changes, in which the anaploid (an abnormal number of chromosomes) played an important role in the development of multicellularity. Consequently, multiplication became the longest long -run polyploid evolution experiment, which contributes to genome duplication biological complexity.

A multi-talented team

Ratcliffe emphasized that rigorous graduate research played an important role in his unexpected success. Four graduate students were integral for the success of experimentation to join research in the early days of their education at Georgia Tech.

“This type of authentic research experience is a life-changing and career-change for our students,” said Ratcliffe. “You cannot achieve this level of learning in the classroom.”

Vivian Cheng, who joined the Rachliff Lab as the first year and graduated in 2022, genetically took the challenge of engineering bugs and tetraploid yeast strains with another student. Rachliff and Tong finished using these similar strains as a major part of their analysis.

“This work is another step towards understanding various factors that contribute to the development of multiculture,” Cheng said, now a Ph.D. Candidates in Urbana-Shampain of the University of Illinois. “It is super cool to see how this single factor of the plouid level affects the selection in these yeast cells.”

Ratcliffe noted that some of his team’s most important conclusions could never be approximate when he started multi -multi. But this is the whole thing, he says.

He said, “The most far -reaching consequences from these experiments are often that we did not aim to study, but it emerges unexpectedly,” he said. “They push the boundaries of what they think.” He and Assistant Professor James Straude expanded the review of long -term experiments in evolutionary biology on this subject, published in a single issue. Nature,

This discovery sheds new lights on the evolutionary mobility of the entire genome repeat and provides a unique opportunity to detect the results of such genetic events. With its ability to fuel future discoveries in evolutionary biology, the task represents an important step in understanding how life develops at both a short -term and long -term levels.

“Scientific progress is rarely a direct journey,” said Tong. “Instead, it comes up with various interconnected paths, often comes together in stunning ways. It is at these intersections that the most thrilling discoveries are made.”