© GEORGE RETSECK; SCANS: PNAS, 112:4405-10, 2015

The emergence of one species from another occurs when the two groups can no longer interbreed. Such reproductive isolation is considered a key evolutionary process, and yet our knowledge of the mechanisms and mutations by which it actually occurs has been confined to conjecture. “We can speculate on the history of evolution from various observations,” says Masayuki Yamamoto, director general of the National Institute for Basic Biology in Okazaki, Japan. “However, it is virtually impossible to reproduce it experimentally.”

Virtually, but not entirely, impossible, it seems. Chikashi Shimoda’s team at Osaka City University in Japan has achieved experimental speciation in the yeast Schizosaccharomyces pombe.

The two sexes of S. pombe—M and P, for “minus” and “plus”—each secrete a pheromone (M factor and P factor), which binds to a corresponding receptor on cells of the opposite sex. This interaction is essential...

“Although their observation may not reflect the real natural history, it supports the concept that changes in the mechanism to select mating partners can be an initial step for speciation,” says Yamamoto, who did not participate in the research.

Pheromone-receptor interactions that drive reproduction have been studied in a variety of life-forms, particularly amphibians and insects, says Shimoda. He therefore suggests pheromone mutagenesis might allow researchers to “extend our achievement to other organisms.” (PNAS, 112:4405-10, 2015)

Transgenic synthetic speciation (PLOS ONE, doi:10.1371/journal.pone.0039054, 2012) Drosophila melanogaster Smaller eyes; different wing veination pattern Mutate five genetic sites to produce flies that can successfully reproduce with each other, but produce nonviable offspring when mated with wild-type flies. Yes, any organism amenable to transgenesis
Pheromone/receptor mutations Schizosaccharomyces pombe No obvious differences Mutate mating pheromone and receptor genes to cause reproductive isolation. Possibly others that use ligand-receptor interactions for reproduction


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