Scientists trace evolution of 25 populations of Vibrio bacteria

Predicting and manipulating natural and man-made microbial systems requires that we differentiate microbial populations according to specific ecological role, so that we can put them to work or mitigate their effects. But the problem of ecological differentiation among microbes is mind-boggling. Most environments contain vast microbial diversity, which is typically measured as genetic diversity in specific marker genes. And, although microbial diversity far exceeds that of all other organisms combined, scientists do not have an accepted concept of species for these creatures. Thus it isn’t possible to take the approach used on plants and animals, where species are first identified and then tested for ecological differentiation. CEE Professors Eric Alm and Martin Polz approached this problem by isolating and identifying over 1,000 strains of Vibrio bacteria from eight liters of seawater, mapping the ecological data onto a family tree and combining information about habitat with the evolutionary history of groups of genes. They apportioned the original 1,000 strains into 25 distinct population groups, then mapped them to a common ancestor.

Professor Eric Alm's Lab
Professor Martin Polz's Lab

"Resource Partitioning and Sympatric Differentiation Among Closely Related Bacterioplankton," Dana E. Hunt, Lawrence A. David, Dirk Gevers, Sara P. Preheim, Eric J. Alm and Martin F. Polz. Science, May 23, 2008.