University of Michigan study challenges neutral theory of evolution
The Story
A study from the University of Michigan challenges a long-standing idea in evolution, finding that beneficial mutations may be far more common than previously assumed. Researchers led by evolutionary biologist Jianzhi Zhang found that many of these mutations do not become permanent because environments keep changing.
Key Facts
- The study was led by Jianzhi Zhang, a professor of ecology and evolutionary biology at the University of Michigan.
- It was published in Nature Ecology and Evolution and supported by the U.S. National Institutes of Health.
- Researchers used deep mutational scanning data from yeast and E. coli to measure the effects of many mutations.
- More than 1% of the amino acid-changing mutations examined were found to be beneficial.
- Using that rate, the team calculated that more than 99% of amino acid substitutions should be adaptive, which does not match actual observations of gene evolution.
- The team concluded the mismatch arises because environments change before beneficial mutations can spread through a population.
- They call this framework Adaptive Tracking with Antagonistic Pleiotropy.
- In a yeast experiment over 800 generations, fewer beneficial mutations became fixed in a changing environment compared with a stable environment.
- An important limitation noted by Zhang is that the data came primarily from single-celled organisms; more data from multicellular organisms are needed.
- Other authors include former U-M graduate students Siliang Song and Xukang Shen and former U-M postdoctoral researcher Piaopiao Chen.
Conflicting Reports
No conflicting reports identified in the source article.
Still Unclear
Whether the same patterns apply to multicellular organisms such as animals, plants, and humans, and why organisms take so long to fully adapt even when an environment remains constant.
Misconceptions
No widespread misconceptions addressed in the source article.
Key Figures
- Jianzhi Zhang, professor of ecology and evolutionary biology at the University of Michigan
- Siliang Song, former U-M graduate student
- Xukang Shen, former U-M graduate student
- Piaopiao Chen, former U-M postdoctoral researcher
Sources: ScienceDaily
