Harvard scientists have solved the long-standing mystery of how some insects form the germ cells the cellular precursors to the eggs and sperm necessary for sexual reproduction and the answer is shedding new light on the evolutionary origins of a gene that had long been thought to be critical to the process.
As described in a November 1 paper published in Current Biology, a team of researchers led by Associate Professor of Organismic and Evolutionary Biology Cassandra Extavour discovered that a cricket, a so-called "lower" insect, possess a variation of a gene, called oskar, that has been shown to be critical to the production of germ cells in "higher" insects, particularly fruit flies. That discovery, Extavour said, suggests that the oskar gene emerged far earlier in insect evolution than researchers previously believed.
"The prevailing hypothesis was that, since only higher insects appeared to possess the oskar gene, that it must have emerged after the two branches of insect evolution diverged," Extavour said. "We found that that can't be right. Oskar is present in both groups of insects, so it must have emerged in their last common ancestor."
Aside from rewriting science's understanding of how germ lines evolved in insects, the finding is also shining fresh light on the importance of looking beyond the traditional models for biological research. Had her team not reached beyond the oft-used fruit fly model, Extavour said, their discovery of the evolutionary history of oskar likely would not have happened.
"There are some questions, especially deep evolutionary questions, you can never get at by examining only one animal," said Extavour, who also serves as the director of the Evo-Devo-Eco Network (EDEN), an initiative funded by the National Science Foundation aimed at providing support to researchers who work outside the traditional model organisms. "And you certainly can't get at them by examining animals that
|Contact: Peter Reuell|