Are mutations in dna advantageous or disadvantageous

Both

Explanation: it is advantageous in a way that it increases the chances for organism to be adjusted in the environment such as survival chance is increased sometimes by positive mutations. Sometimes replacing the wrong gene with right gene by the mutation is advantageous.

Sometimes, mutations in DNA doesn't have any effect, means it has neutral effects.

It is disadvantageous sometimes that it results in the occurrence of disease which may be serious disease like heart disease. Tiny mutations also results in disorders.

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.