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Study Takes a Fresh Look at Relationship Between Trade-Offs and Evolution

Researchers illustrate how plastic behaviors enable organisms to gain competitive edge by exploring new regions of phenotypic space.

Xiao Yi

Postdoctoral associate Xiao Yi in the lab.

Xiao Yi and Antony Dean (EEB/BTI) conducted experiments that allowed bacteria to evolve in a fluctuating environment, alternating between growth and selection for motility, or movement. While adaptation initially increased overall swimming speed at the expense of growth, by replacing a single amino acid that regulates motility the researchers found that individual cells at later stage of evolution reduced motility during growth, and the fraction of motile cells increased as selection for motility was approaching.

“Our work begs rethinking of the relationship between trade-offs and evolution: In diametric variance to the conventional wisdom that trade-offs constrain evolution, they indeed constitute opportunities for biological innovations to evolve,” says Yi, a postdoctoral associate currently in the Travisano and Kazlauskas labs.

Yi plans to build on this initial insight by developing a theory that depicts rigorously how proximate mechanisms, such as functional tradeoffs, and ultimate mechanisms, such as population genetic processes, can interact with each other  to impact the evolutionary trajectory of life.

The study could help shed light on major transitions in evolution such as multicellularity. “Our discovery indicates that strong selection coupled with strong constraint naturally makes outliers easier to crop out, intuiting emergence of the transitions,” says Yi. “In the context of climate change, the altered environments might reconfigure the adaptive landscape and put organisms in new fronts of tradeoffs. Then we expect to see new behaviors to evolve in the face of mass extinction.”

The study, titled “Phenotypic plasticity as an adaptation to a functional trade-off,” was published last month in the journal eLife.  


November, 2016