A team of researchers conducted an experiment that allowed them to watch the evolution of viruses in real time. The viruses evolved very quickly and began to split into separate lineages, beginning the speciation process. The findings will help researchers better understand microbial evolution. The details are in a paper that was just published in the journal Science.
Speciation is the process of a population evolving into separate lineages that eventually become genetically distinct species. This process is a major component of evolution but can be difficult to study since evolution works so slowly. Most experiments designed to study speciation are long and involve plants, animals, or fossil records. Finally, a scientist from Michigan State University had the idea to use microbes to study the effects of long-term evolution and speciation.
Researchers from the University of California in San Diego built on the previous study to design an experiment that could track the speciation of bacteriophages. Bacteriophages are viruses that specifically infect bacteria. The team first developed a bacteriophage called bacteriophage λ (lambda). The virus uses Escherichia coli bacteria as a host but there are two possible routes of infection. Some of the bacteria had LamB receptors and others contained OmpF receptors. The bacteriophage could infect the bacteria at either receptor site. The microbes were mixed together and allowed to evolve naturally over a period of one month.
The team found that as time went on, some of the viruses began to specialize in infecting bacteria with one receptor type while others focused on the alternate receptor. Many of the viruses lost the ability to target the receptor they weren’t specializing in. Within a month, bacteriophages that hadn’t specialized at all went extinct due to competition from their specialized neighbors. Even the authors of the paper were shocked that microbial evolution was happening so quickly. By the end of the experiment, there were two distinct viral lineages that specialized in just one kind of bacterial receptor. The viral lineages were genetically distinct and some couldn’t reproduce with viruses of the other lineage. This provides even more evidence of how speciation works as well as proof of just how fast viruses can evolve into entirely new species.
The paper places emphasis on the idea of using microbes to study evolutionary processes. Viruses evolve very quickly, allowing speciation to be observed in the laboratory over a short time period.
Meyer et al. Ecological speciation of bacteriophage lambda in allopatry and sympatry. Science (2016).