How do mutations become more or less common in a population over the course of generations?. Earth & Marine Sciences

Mutations may be detrimental (or even lethal); they may be harmless; or they may be beneficial in some way. Detrimental mutations should become less common over the course of generations because individuals with those mutations shouldn't do very well relative to other individuals. If a mutation is beneficial, however - one that helps an organism fight off diseases, thrive in its environment, or improve its ability to find mates, for example - that individual should produce more offspring on average than individuals without the mutation. Mutations can also become more or less common in a population due to chance, a process called genetic drift.