Researchers studying yeast reproductive habits have for the first time observed a rapid method for the creation of new species, shedding light on the way organisms evolve and suggesting possible ways to improve yeast biotechnology and fermentation processes used in beer and wine-making.

"Most models of speciation require gradual change over a very long period of time, and geographic or ecological isolation for a new species to arise," says University of Houston biologist Michael Travisano. "Our study suggests that mating two separate species to produce hybrids can result in a new species readily and relatively quickly, at least in yeast, but possibly in other organisms as well."

Travisano, an assistant professor in the UH Department of Biology and Biochemistry, says the findings extend the range of known mechanisms that cause reproductive isolation. The study appears in the Nov. 29 issue of the journal Science.

Duncan Greig, a postdoctoral researcher in Travisano's lab, conducted experiments that put two different species of yeast together, Saccharomyces cerevisiae and Saccharomyces paradoxus. One way that yeast, a one-celled organism, can replicate is by producing spores. When spores from these two species joined, they produced hybrid offspring, similar to crossing a female horse with a male donkey and getting a mule.

Unlike mules, which are sterile, a few of the yeast hybrids were fertile. Those hybrids produced viable offspring when they were allowed to "autofertilize," which means an individual's spores fertilized themselves to produce an offspring without involving another yeast cell.

However, the hybrids did not produce viable offspring when mated back to their parent species. "Other labs have generated hybrids such as these before, but we went a step further and crossed the fertile ones back with th
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Contact: Amanda Siegfried
asiegfried@uh.edu
713-743-8192
University of Houston
28-Nov-2002