Biological Science (6th Edition)

Published by Benjamin Cummings
ISBN 10: 0321976495
ISBN 13: 978-0-32197-649-9

Chapter 1 - Biology and the Tree of Life - Review - Page 14: 4

Answer

Both the food competition hypothesis and the sexual competition hypothesis explain why giraffes have long necks. Both 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. These longer-necked giraffes, then, are more frequently passing on their physical characteristics through reproduction than their shorter-necked counterparts are. This, too, is a case of natural selection.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.