In a population of wild bees, a mutation resulted in slightly larger wingspan in some of the bees. This larger wingspan made the bees more efficient in their flights to flowers to collect nectar. Thus, these bees became more successful at surviving and reproducing. This trait was passed on to offspring, and eventually the larger wingspan variety of bee replaced their smaller-winged relatives completely. Because this mutation produced a specific wing trait that was passed onto offspring, the mutation must have occurred .