Answer
Both the food competition and the sexual competition hypothesis explain why giraffes have long necks.Hypotheses are valid examples of how natural selection can influence the physical characteristics of a species.
Work Step by Step
Both the food competition hypothesis and the sexual competition hypothesis explain why giraffes have long necks.
The food competition hypothesis postulates that giraffes with longer necks tend to thrive more by being able to reach higher on trees than those with shorter necks. This leads the longer-necked giraffes to reproduce more often than those with shorter necks. This, then, is a case of natural selection, where more giraffes with longer necks pass off their physical characteristics to their offspring.
The sexual competition hypothesis postulates that giraffes with longer necks demonstrate greater ability to defeat their shorter-necked competitors in sexual competition.
