Chapter 10. Chapter 10: Evolution and Extinction

Guinea pigs aren't pigs and aren't from Guinea; they're rodents from the Andes (Peru, Bolivia, Equador). About 7000 years ago, wild Guinea pigs were caught and bred by people, mostly as food. Guinea pigs became part of the social fabric of the native peoples of the Andes, and several different varieties arose, largely based on their size and how much meat they produced. Europeans brought Guinea pigs back to Europe, where they became valued more as pets than as food, and many "fancy" varieties with different lengths of hair, different color patterns, and so on, were bred. Recently, agricultural researchers in Peru have been breeding the largest Guinea pigs out of every litter, hoping to create a jumbo-sized Guinea pig that could provide meat using far fewer resources than traditional livestock.

The story of the Guinea pig is an example of:

Thought Question: How is artificial selection different from natural selection?

Although there may be nothing as American as apple pie, apples themselves are far from American. Apples are in fact from central Asia, roughly present-day Kazakhstan. In that region, there are ancient mountain forests where perhaps 7 out of every 10 trees is an apple. Although there are relatively few varieties of apples grown around the world for their fruit, each wild apple is different from its neighbors in terms of fruit size, shape, color, and flavor, though they are all the same species.

This suggests that these apple populations probably have:

The apples you find in the market are actually clones. When an apple is found that has desirable traits, such as sweet flesh or an attractive color, growers can remove a branch from that tree and graft (essentially fuse or splice) it onto another, making a new tree genetically identical to the first. This way, growers never have to worry about the variation caused by sexual reproduction shuffling up the desirable traits they found in their new tree. The process of cloning apple trees through grafting to perpetuate their desirable traits is an example of:

Thought Question: The answer to the previous question is 'none of the above'. Why is cloning apple trees not an example of artificial selection?

Which of the following statements is false?

When evolution is referred to as a "theory," it is implied that:

Which of the following is true about evolution?

Pandas have five forward-pointing toes on each foot; the wrist bones on their fore paws have an outward-pointing structure that helps pandas grip bamboo stalks and strip the leaves from them. Although called the panda’s "thumb," it is not evolutionarily a thumb. This fact illustrates best the fact that:

1) Why doesn’t my pet goldfish grow legs?

2) Why are there still apes if humans evolved from them?

3) Why would evolution still happen? Aren’t humans proof that it’s finished?

4) Our appendix doesn’t do anything. Doesn’t that disprove evolution?

5) How is survival of the fittest different from evolution?

6) Why should we care that species are going extinct?

7) How do you know evolution is right when it’s so slow that you can’t observe it?