Mutation refers to a sudden and permanent change of the DNA of a cell.

Only those mutation occurs in gamete can bring along the effect to the filial generation, i.e. offspring.

But, then, how does evolution continue as their parents are affected by the environment and cannot carry the varied gene to the next generation?

Or Evolution does not involve mutation?

But if they do produce offspring from that gamete that contains the mutation, that offspring will carry the mutation.

random mutations are only a small part of evolution. And remember, species multiply. Out of hundreds, thousands, millions, billions and so on you would think some mutations are good helpful ones that get passed on.

Only mutations that occur during the meiosis of cells into gametes will be passed on into the offspring.

 

If an adult individual develops a mutation in one of his cells during mitosis then the mutated cell will usually become cancerous and either be killed off by the immune system, or grow into a tumour.