The predator bacterium, Bdellovibrio bacteriovorus, is equipped with a flagellum that enables it to seek actively for its prey (left). The right-hand image shows the predator inside its prey, in the process of feeding off the cytoplasm. (Credit: Copyright Edouard Jurkevitch)
Observing the mechanisms of evolution in order to understand how a species adapts to another under different ecological conditions was the goal of researchers at the Laboratoire Écologie et Évolution at CNRS, Université Pierre et Marie Curie and the École Normale Supérieure. They studied two bacteria — a predator and a prey — over 300 generations in a controlled environment.
For the first time, these scientists were able to demonstrate that the coevolutionary process is dependent on ecological conditions. Indeed, under certain conditions, the prey becomes resistant to the predator, which itself evolves so that it can attack this new prey. In addition, the scientists issued a warning against the previously envisaged use of this predator (Bdellovibrio bacteriovorus) as a “living antibiotic” because, like other antibiotics, this could lead to the selection of resistant pathogenic bacteria.
Since publication of the Origin of Species by Charles Darwin 150 years ago, it has been known that one of the dynamics of evolution is natural selection. Its results depend on environmental conditions and interactions between the species present (competition, predation, parasitism, cooperation). Some twenty years ago, a new field of research — experimental evolution — started to develop, and it has enabled scientists to better understand the mechanisms underlying evolution.