The group at Michigan State University has maintained and followed the evolution of E. coli since 1988, when Richard Lenski set up 12 flasks. Scientists can compare the bacteria at different points in time by bringing them back to life with the help of frozen sub samples.
After 60,000 generations, E. coli cells are twice the size of their ancestors. Is the increase in size accompanied by changes in metabolism and population size?
The researchers at the Center for Geometric Biology collaborated with Richard Lenski. The results are published in the PNAS.
The rate at which organisms turn energy into maintenance and production is dictated by metabolism.
Smaller species have lower metabolism rates than larger ones, and they are more efficient. Smaller species can reach densities faster than larger ones, but total population mass is greater in larger species.
Does the above hold true in a species?
The size range within a species isn't large making it difficult to test.
TheLenski lines circumvent this problem. The samples from the original E. coli were sent by Richard's lab.
The project was led by Professor Marshall and Dr. McDonald from the school of biological sciences.
Professor Marshall said that as the cells grew bigger through evolutionary time, their metabolism rates increased but were lower relative to their size.
He said that populations of larger cells had lower population densities than their smaller ancestors.
The big surprise was that populations of larger cells grew faster than smaller cells.
The experiment has shown that the energy required to produce a new individual is not proportional to its mass.
Why would a bigger cell be cheaper to build and maintain?
E. coli cells use a lot of energy. Smaller cells have lower maintenance costs because they have smaller surface areas. The costs of genome replication are lower for larger cells because they have slightly smaller genomes.
The evolved cells have fine-tuned their genetic components in this highly predictable environment.
Remarkably, it seems evolution can decouple the costs of production from size, and there is no downside to increasing growth rates for the larger evolved cells in terms of yield.
More information: Dustin J. Marshall et al, Long-term experimental evolution decouples size and production costs in Escherichia coli, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2200713119 Journal information: Proceedings of the National Academy of Sciences Citation: Evolution experiment with bacteria challenges conventional wisdom about size and the cost of production (2022, May 23) retrieved 23 May 2022 from https://phys.org/news/2022-05-evolution-bacteria-conventional-wisdom-size.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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