Scientists from the University of Michigan conducted an experimental test to determine which of the factors — diversity or random mutations — plays the main role in the evolutionary process. Preliminary research results are published in the bioRxiv preprint archive.
Biologists grew Escherichia coli for 300 days. Populations of bacteria with different levels of genetic diversity were placed in Petri dishes with a nutrient medium containing glucose and the amino acid D-serine. The degree of diversity of the population varied from zero (all bacteria belonged to the same line) to the maximum that scientists were able to recreate by mixing and comparing samples before the experiment. In total, two thousand generations were produced, and researchers measured the degree of adaptability of microorganisms at several stages of the test.
It turned out that in the 50th generation, those populations that were more diverse had a clear advantage, that is, they evolved to better compete for food. However, over time, the advantage decreased and by the 2000th generation, it had almost completely disappeared.
The authors of the work assume that the influence of the original diversity is lost due to the fact that random mutations are the main driver of evolution, at least in Escherichia coli. However, to confirm the results, it is necessary to conduct experiments with more complex organisms.