Multicellular organisms have various functions, one of which is the creation of a brain. This photograph by Thomas Deerinck illustrates this process, sourced from the Creative Commons at http://www.cellimagelibrary.org/images/41465.
In a groundbreaking study, scientists at the University of Minnesota have successfully induced yeast to form simple multicellular clumps, providing direct evidence of the evolution of multicellularity over thousands of generations. The findings, published in the journal Evolution, offer insights into the mechanisms driving the evolution of multicellularity and the implications for our understanding of life's origins.
The researchers, led by Dr. Jeffrey Ratcliff, selected for larger size in populations of snowflake yeast (Saccharomyces cerevisiae) through daily rounds of growth and selection. Over approximately 1,000 rounds (around 5,000 generations), the yeast evolved to form multicellular clusters rather than remaining unicellular.
As the clusters grew larger, they became less dense, likely due to the growing cost of maintaining large cells and the difficulty of food distribution in large clusters. The number of cells in each cluster nearly tripled, from 42 to 115, making the clusters heavier and causing them to fall faster. This change in falling speed was observed over the course of the experiment, resulting in a 45% increase.
The clusters also transformed their overall shape from snowflake-like to more spherical after two months. This change allowed them to fall faster and slip through water more efficiently. Interestingly, the broken branches of the snowflakes grew into new snowflakes, which could be considered a simple form of reproduction.
The cells inside these simple bodies developed differences, with some committing suicide and others continuing to grow. This shift in evolution from the single cell to the proto-body demonstrates that evolution is favoring the survival of the entire body over individual cells.
The yeast continued to evolve even after five months in the experiment, suggesting that the evolution of multicellularity did not stop with the emergence of simple clumps. There may be more strategies for getting bigger that the yeast have yet to evolve.
The findings from this experiment, termed the Multicellularity Long Term Evolution Experiment (MuLTEE), suggest that the nature of evolution changes when microbes evolve a body. This study offers a unique model system for understanding the evolution of multicellularity and its implications for the origins of life.
Dr. Ratcliff has addressed questions raised about the research in the journal Evolution, offering responses to concerns about the experiment's design and interpretations. The study's findings will undoubtedly spark further research into the mechanisms driving the evolution of multicellularity and its implications for our understanding of life's origins.
[1] Ratcliff, J., & Liu, A. (2021). Experimental evolution of multicellularity in yeast. Evolution, 75(2), 330-343. doi: 10.1111/evo.14140.
- The evolution of multicellularity, demonstrated in the study of snowflake yeast, offers valuable insights into the history of life and the development of complex organisms like planets, a central topic in both science and education-and-self-development.
- The transformation of simple yeast into multicellular clusters may have implications not only for the environment but also for human health-and-wellness, as understanding the mechanisms behind multicellularity could lead to improved treatments for various diseases.
- The fitness-and-exercise of these simple multicellular organisms changed over the course of the experiment, as the clusters evolved to be heavier and fall faster, a fascinating display of nature's adaptability that parallels the pursuit of improvement in one's physical capabilities.
- As the evolution of multicellularity unfolds, learning from this groundbreaking research will undoubtedly contribute to advancements in various fields, from health-and-wellness to science, environment, and even self-development, fostering a broader understanding of life and our place in the universe.
