A potential mechanism has been found for what seem to be “leaps” in evolution. For example, there is no middle ground on the number of wings on an insect or limbs on a primate. So how is the “jump” made? It could be “partial penetrance.”
“If you take a bunch of cells and grow them in exactly the same environment, they’ll be identical twin brothers in terms of the genes they have, but they may still show substantial differences in their behavior,” says Avigdor Eldar, a postdoctoral scholar in biology at Caltech and the paper’s first author. These sorts of variations—or noise, as the researchers call it—can actually allow a mutation to have an effect in some organisms but not in others. For example, while some genetically variable cells will show the expected effect of the mutation, others may still behave like a normal, or wild type, cell. And still others may do something else entirely.
“These mutant cells don’t only show a different morphology,” Eldar notes. “They show more variability in their behavior. In a population, you can see a mixture of several different behaviors, with some cells doing one thing and others doing something else.”
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