Bacteria-virus arms race provides rare window into rapid and complex evolution

Rather than the evocative plants and animals of the Galapagos Islands that Darwin studied in forming his theory of evolution, Postdoctoral Scholar Joshua Borin and Associate Professor Justin Meyer of UC San Diego's School of Biological Sciences are documenting rapid evolutionary processes in simple laboratory flasks.

Borin and Meyer set bacteria and viruses together in a closed laboratory flask – just two teaspoons large – to study coevolution in action. As viruses infect their bacterial neighbors, the bacteria evolve new defensive measures to repel the attacks. The viruses then counter these adaptations with their own evolutionary changes that work around the new defensive measures.

In only three weeks, this accelerated arms race between bacteria (Escherichia coli) and viruses (bacteriophage, or "phage") results in several generations of evolutionary adaptations. The new findings, published in the journal Science, reveal the emergence of distinct evolutionary patterns.

"In this study we show the power of evolution," said Meyer, an associate professor in the Department of Ecology, Behavior and Evolution. "We see how coevolution between bacteria and phage drive the emergence of a highly complicated ecological network. Evolution doesn't have to be slow and gradual as Darwin thought."

Image source: Josh Borin, UC San Diego.