The only mutations that matter to large-scale evolution are those that can
be passed on to offspring. These occur in reproductive cells like eggs and sperm
and are called germ
A single germ line mutation can have a range of effects:
No change occurs in phenotype
Some mutations don't have any noticeable effect on the phenotype of an
organism. This can happen in many situations: perhaps the mutation occurs in
a stretch of DNA with no function, or perhaps the mutation occurs in a
protein-coding region, but ends up not affecting the amino
acid sequence of the protein.
Small change occurs in phenotype
A single mutation caused this cat's ears to curl backwards slightly.
Big change occurs in phenotype
Some really important phenotypic changes, like DDT resistance in insects are
sometimes caused by single mutations. A single mutation can also have strong
negative effects for the organism. Mutations that cause the death of an
organism are called lethals — and it doesn't get more negative than that.
There are some sorts of changes that a single mutation, or even a lot of
mutations, could not cause. Neither mutations nor wishful thinking will make
pigs have wings; only pop culture could have created Teenage Mutant Ninja
Turtles — mutations could not have done it.