Question

If acquired traits don't lead to evolution,how does long necks in one generation of giraffes becomes a traut?

Answer 1

According to Lamarck's use and disuse theory, giraffes bad long necks so that they could reach plants better.

This is incorrect.

Consider the situation wherein you have acquired a scar somewhere on your body. This scar could be consider3d an acquired trait. However this scar does not pass onto your progeny.

Why?

Because only changes that affect the sex chromosomes are transmitted onto the progeny.

For a trait to be stably expressed in an organism, it must be passed on through generations of its ancestoes.

If we assume that giraffe necks are acquired traits then it will definitely not be passed onto its progeny. However, if the trait was caused by a mutation leading to change in sex chromosomes, then the long necks of giraffes could be explained