Perhaps this scientific experiment can rightly be called the most long-lasting in the region of observation of the evolution of a living organism. Started in 1988, the American evolutionary biologist Richard Lenski. Together with his colleagues at the University of Michigan, Richard began to observe changes in 12 cultures of the bacterium E. coli (Escherichia coli). The following year, this long-running experiment will be 30 years old, but Richard Lenski is not going to stop there.
The aim of this experiment was to find answers to extremely important to evolutionary biology questions. For example, how changes in time the speed of evolutionary change? What is the repeatability of evolutionary change for different populations existing in the same environment? What is the ratio of evolution at genotypic and phenotypic levels? And so on. The choice fell on E. coli only because this organism is characterized by rapid change of generations, and can also boast of an extremely small genome, which simplifies its study.
After 30 years of the investigated E. coli has replaced 67 000 generations. To make it clearer, the equivalent of human evolution is a little more than 1 million years. Scientists surprised by the fact that bacteria continue to evolve, in spite of a static and unchanging simplicity of the environment they are in. According to the hypothesis of the researchers, the constant evolution of Escherichia coli to gradually affect changes in its environment. Thus, it is a kind of closed ecosystem, where the evolution changes organisms and their environment.
“Our study, published in the journal Nature, offers readers a detailed understanding of the molecular details of adaptation over long evolutionary timeline. We believe that the results of our experiment will allow a better understanding of the evolutionary process. The most surprising part of our discovery is that although the population of E. coli in our experiment for a long time developed in a very simple environment, they are still able to adapt to the environment,” — said study co-author Dr. Mike McDonald.
All 12 cultures of E. coli significantly improved its competitive fitness for the past 30 years of evolution. They began to grow faster, have larger cells than their ancestors, but each culture has developed its own unique path to better physical shape. For each crop, the evolution took its course. One of the most remarkable evolutionary achievements of one of the cultures became her new ability to eat citrate in addition to glucose. This in the coliform bacteria was not observed.
Scientists are not going to stop the experiment, despite the fact that it requires more effort, time and money. They know how important this project is for science, so plan to observe Escherichia coli over the next decades. What this bacterium is still able to surprise the researchers, only time will tell. To see the results of the study in the journal Nature.
An experiment about 30 years, as scientists have observed the evolution of bacteria
Sergey Grey