While the generally accepted driving force behind evolution is survival of the fittest genes, new research shows that some mutations may survive because they hitchhike on the success of others.
The mechanics of evolution are simple and elegant: If an organism mutates and that mutated gene gives the organism better odds at surviving, then it will live long enough to reproduce and pass the gene to the next generation. Meanwhile, organisms without the gene won’t survive and will die out. In short, it’s survival of the fittest. New research however, suggests that this may not always be how evolution works.
In fact, instead of single gene mutations driving evolution, it may be groups of genetic mutations. In addition, some mutations may not be beneficial at all, but rather hitchhike on the success of others. New research from Princeton University studied 1000 generations in 40 yeast populations, and the researchers found that around five to seven gene mutations are needed to for a strain to survive, rather than just one.
Graph showing the evolution of a yeast population as it undergoes mutations (colored areas)
“The finding goes against the traditional view of evolution being determined by individual mutations that provide a large fitness advantage by themselves,” said Michael Desai, part of the research team, “We found that small groups, which we call cohorts, of mutations were associated with increased survival. No single mutation is driving adaptation. The whole group, which includes hitchhikers, drives adaptation together.”