Download Tree of Life Questions and Answers

Charles Darwin and the Tree of Life
1. In 1831, the Beagle set off on a voyage across the
Atlantic.
2. In 1835, the Beagle landed on the Galapagos Islands.
What did Darwin notice about the tortoises between the
different islands?
Darwin claimed that just by looking at a tortoise, he
could tell what Island it had come from based on its shell.
If the tortoise had come from a watered Island, it had a
rounded shell. If the tortoise had come from a dry Island,
it had a peaked shell so that it could reach higher vegetation.
3. What did Darwin begin to ponder about on his voyage homebound?
Darwin started to wonder if it was possible for species to change slowly over time. This
would imply that maybe species weren’t fixed.
4. Darwin noticed that the majority of animals produce many more young than actually live
to reproduce themselves. Explain the example using the Female Blue Tit Bird.
This female bird lays dozens of eggs each year. However, only two need to survive and
breed themselves in order to maintain the numbers of their population. The two birds that
survive are likely to be the healthiest and best suited to their particular environment, and
thus, would pass on these characteristics to the next generation.
5. “Only the fittest survive” was a key idea of the process of natural selection.
6. Darwin noticed differences between Finches he had brought back from the Galapagos
Islands. What were these differences?
Darwin noticed that all the Finches he had brought back were very similar, except for their
beaks. Some Finches had very thin beaks which it used to catch insects, while other Finches
had very thick and heavy beaks. These latter Finches came from a different environment
that was abundant in nuts, and so the Finches used their thicker beaks to crack open nuts.
7. Over the vastness of time, and particularly if species are invading new envrionments,
small changes could amount to very radical changes.
8. How is the domestication of dogs and nature’s selection similar?
Dogs breeders select for puppies that have the characteristics that they (the breeders)
want. Nature does something to a similar effect, such that over the course of time, young
animals that are best suited for the particular environment will be selected for/survive.
Both processes produce a lot of variation amongst the animals.
9. What is an important criterion for deciding if animals are different species?
An important criterion to consider would be if they can interbreed or not.
10. Nature has been selecting between animals for hundreds of millions of years.
11. What did Darwin receive in 1858?
Darwin received a package from Alfred Wallace. Wallace had sent Darwin an essay that set
out the exact same idea as Darwin (evolution by natural selection).
12. What is the Linnaean Society? What did the Linnaean Society’s reaction to Darwin and
Wallace’s observations?
The Linnaean Society was the place where scientists held meetings to present and discuss
papers about their observations and thoughts. Papers from both Darwin and Wallace were
presented in 1858, however neither paper made much of an impression with the Society.
13. Darwin’s writings were finally published in 1859. The title of his book was The Origin of
Species.
14. What was the public’s reaction to Darwin’s book?
Darwin’s book caused an outrage throughout the world. Some people attacked the book on
the grounds that it contradicted the story of Creation.
15. How can geologists use layered rock/compacted sand to date fossils?
As you descend through layers of rock, you are essentially going back in time. Fossil species
that come from/are found in a particular layer of rock, come from a particular age in time.
If you can recognize time period, then you can piece together the outline of life’s history.
16. Darwin believed that there should be connections not just between similar species but
also between the Great Animal groups. So, there should be intermediate forms between the
Great groups.
17. Two years after the publication of the Origin of the Species, Richard Owen purchased a
fossil. What was so special about this fossil?
This fossil was called Archaeopteryx. This fossil showed feathers on its wings and down its
tail. It had claws on the front of its wings; it did not have a beak, and instead had a jaw with
teeth and a line of bones supporting its tail. This fossil was part-bird and part-reptile; a link
between these two Great groups.
18. What bird alive today illustrates the link between modern birds and reptiles? Why?
The Hoatzin has claws on the front of their wings. There is evidence that their wings are
modfified fore-legs and some had toes with claws on them. These birds use their claws to
hang onto branches when other animals try to shake them from their nests.
19. What features of the Platypus suggest it is an early mammal? What features of the
Platypus suggest is part-reptile?
The Platypus gives us an idea of how the first mammals evolved. They have fur, which is
common to mammals, as well, when it comes time to breed, the Platypus will go into a
burrow to build a nest, and lays eggs (this is reptile-like).
20. Links between the Great animal groups are not missing, but instead exist as fossils and
as living animals.
21. Briefly describe one example of fossils that suggest that life did not begin suddenly with
the complex animals of the Cambrian period.
In 1957, an impression was found of an organism in rocks that were known to be older
than the Cambrian rocks. This organism had a central stem, and branches on either side.
22. Less than fifty years after the publication of the Origin of the Species, a discovery was
made by Marie Curie. What did she discover?
She discovered that some rocks contained an element called uranium; this decays over time
at steady rate through a process called radiation. Today, the method of dating by measuring
changes in radioactivity has become a lot more refined.
23. Ancient rocks have been dated back to 562 million years ago.
24. Another objection to Darwin’s theory soon arose. What was the objection?
If all animals in a group have a common origin, how is it that some animals are distributed
all over the world? Frogs In Europe and Africa are also found in South America on the other
side of the ocean, yet frogs cannot survive/swim in sea water.
25. In 1912, what did geologists suggest? Was this idea ever confirmed?
Geologists suggested that at one time, all the continents of the Earth were grouped together
to form one huge supercontinent and that over time, this broke up and the pieces drifted
apart. This idea was confirmed in the 1960’s. Some animals originally evolved on the
supercontinent and then travelled on various fragments as the continents drifted apart.
26. Darwin believed that the human eye became increasingly complex over a long period of
time. Each stage of development was an improvement on the previous one.
27. Genetically speaking, what else does natural selection require?
Natural selection requires that an animal’s characteristics are inherited from one
generation to the next generation.
28. In 1953, (about 100 years after Mendel’s time), what did Watson and Crick discover?
Watson and Crick discovered the double helix shape of DNA.
29. What three things have since been learned about DNA?
We have learned that a gene can be taken from one animal and function in another (ie.
transferring luminescence from jellyfish into rats), that the genetic code can reveal
relationships (ie. paternity) and can also reveal whether one kind of animal is related to
another (ie . a branch of the elephants and manatees).
30. About 150 years after the Origin of the Species, genetics has confirmed what
fundamental truth?
That all life is related.
31. Please make jot notes about the complex Tree of Life. Include the order of which animal
groups emerged and a few distinguishing features between them.
32. What features suggest that humans share a close relationship with chimpanzees?
We are very similar to chimpanzees and our DNA confirms this. We share the range in our
internal organs, the chemistry of our blood and the way our bodies work.
33. Because we can disentangle the relationship between animals and plants, we can
foresee the consequences when we start to interfere with those communities.