Giraffes are herbivores that initially had shorter necks. They are found in grasslands and areas where trees grow tall. To feed on leaves from tall trees, giraffes had to stretch their necks. This behavior paved the way for of giraffes with longer necks. A giraffe’s long neck is a adaptation.

Natural selection is the process of differential survival and reproduction of the individuals, which have more favorable phenotypic characteristics than others. Natural selection favors the survival of the organism in adverse environmental conditions. Structural adaptation refers to the changes in the physical features of the organism, in the shape, size, covering of the body and others, which favors the survival in the native environment.

The primitive giraffe species had competition with other grazing animals. The long and massive body required more food. Therefore, giraffe species evolved with increased neck length in order to reach the canopy of long trees, with nourished leaves. The trait of long neck transmitted to subsequent generations. This was an example of structural adaptation with respect to natural selection.