Chapter 11 (Video)

After his journey on the HMS Beagle, Darwin made this now-famous sketch in his notebook. Which ideas does it represent?

All species are linked to one another by common ancestry. All species are connected to one another in a "family tree." Species descend from other species just as naturally as children come from parents.

What did Wallace conclude from observing that the bones in manatee flippers look similar to the bones in a human arm and hand?

Manatees' arm and finger bones are evidence that manatees share a common ancestor with land mammals.

When Charles Darwin set sail on the HMS Beagle, what did he and most of his contemporary scientists think about the origin of species?

Most scientists, including Darwin, thought each species was specially created by God in its present form and did not change over time.

As Wallace traveled the Malay Archipelago, he noticed that western islands had placental mammals, like monkeys. Eastern islands had marsupial mammals, like kangaroos. How did Wallace explain this distribution?

The western islands were once connected to Asia and the eastern islands had been connected to Australia. The islands had never been connected to each other.

Darwin and Wallace made independent observations in different parts of the world. Which statements are true?

Both observed slightly different species on nearby islands and concluded that species could change over time. Both collected huge numbers of specimens and realized that individuals vary within species. Both witnessed nature up close and realized it was a battlefield with massive casualties.

Darwin and Wallace independently arrived at the same conclusion that species change over time. Which observations supported their conclusions?

Bird families clustered geographically: cockatoos in the Malay Archipelago and Australia, macaws and hummingbirds in the Americas.Mockingbirds from different Galapagos islands had subtle, consistent differences. Birdwing butterflies were found throughout the Malay archipelago, but species differed slightly from island to island. The fossilized remains of giant sloths were similar to the smaller, living sloths Darwin encountered. The bony shells of armadillos resembled fossilized shells from the extinct Glyptodon. Tortoises from different Galapagos islands have distinct shells.

Which observations led Darwin to establish a relationship between extinct and living animals?

The fossilized remains of giant sloths were found in places where smaller sloths now live. The bony shells of armadillos resembled the shells of ancient Glyptodon fossils.