Answer Key to Evolution Study Guide 2015 (separate sheets of paper will be needed)
(exact phrasing does not count, as there are multiple ways to state correct answers)
1. What are the steps of speciation? Separation, adaptation, and division
2. What is evolution? Change in the characteristics of a population over time, where the change is
inherited.
3. What are vestigial structures, give an example, and how do they support evolution? Vestigial
structures are the remains or remnants of once useful structures, but are not useful to the
creature that has them. Examples are the tail bone of the human, and the hind leg bones of
the whale. They let you trace evolution backwards to a prior organism.
2. Provide a real-life example ( to include the name of the organism - , the environmental
pressure, and the successful adaptation) that has occurred in nature for :
Organism name
Environmental pressure
Successful adaptation
Bird
Our prey hides from us
Great eyesight to see them
Dreaded humans keep dosing us
Develop strains that laugh at
(bacteria)
with antibiotics
antibiotics, “back at ya, Human!”
cactus(a plant)
Drought, animals steal our water
Sharp spines
camel(a
Drought in desert
Store water in humps
mammal)
3. List AND describe the steps that occur in natural selection:
Overproduction Species produces more offspring than can survive.
Genetic variation Differences between individuals, all inherited, affect their ability to
survive.
Struggle to survive The fittest survive, the rest die off.
Successful reproduction: The fittest reproduce, the others (having died) don’t.
4. Compare and contrast natural selection with selective breeding: Both involve modifications in
species. For natural selection, it’s Nature letting the fittest survive and the others die off. For
selective breeding, it’s humans who choose what characteristics they want to encourage in a
species.
5. Compare and contrast selective breeding with natural selection. BOTH involve the change of
the characteristics of a population of organisms. For selective breeding, humans try to control
the process. For natural selection, impersonal Nature uses survival of the fittest to weed out
the unfit.
5. List four kinds of evidence in support of evolution, and describe the support:
Kind of evidence
Fossil Record
Description of support
Provides physical evidence of the historical record of the
changes in species and of evolution.
Vestigial structures
Presence of once useful structures that have no current use to
the species demonstrates that they evolved from creatures
that had those structures and they were useful then.
Close similarities among the early embryos are evidence that
Embryonic comparisons
they once shared a common ancestor
DNA comparisons
DNA analysis is strong evidence for the common ancestors of
not only species but all organisms.
6. Describe the principal process by which fossilization occurs: Sediment (mudslide, volcanic ash, etc)
forms at about the same time as an organism dies and is buried in the sediment. Pressure and time
turn the sediment into sedimentary rock, and the fossil is preserved within the rock.
7. Describe the evolution of the whale, to include at least five adaptations and a rough time line.
Condylarth, about 60 MYA (Million Years Ago), a wolf-like mammal, gets hearing adaptation letting
it hear better under water, broader jaw to browse on under-water food items, evolves to Pakecetus,
about 55MYA, legs get shorter, gets webbed feet to evolve to Ambulocetus, about 50MYA, gets
bigger lung capacity massive tail to evolve to Rodhocetus, 46 MYA, legs evolve to flippers, gets even
bigger, spends all time in water, blow hole develops, evolves to Prozeuglodon 40MYA, evolve echolocation organs that let them make clicking sounds and then listen to echoes so as to location prey
better, become Squalodontids 45MYA, and the rest is history.
9. Describe the evolution of the eyeball, to include one adaptation found in the eyeballs of cow
eyeballs not found in humans: Sight began as simple light sensors, evolved to a recessed area for the
light sensors to allow better focusing, evolved to a pin-hole to improve focus, then evolved to a liquid
filled area like an eyeball to allow for consistent focusing, with nerve cells transmitting images to
brain, then evolved to have muscles to shift the focus of the eyeball, then added a lens to improve
sharpness of focus, then evolved to add reflective tapetum to improve night vision – sorry, Humans,
you don’t get those, but cows do.
11. Imagine that you are Charles Darwin, and that fires have destroyed all your reports, your
manuscript for your book, and your records. You have the remainder of the block to write a onepage letter to the world in which you explain who you were, when you lived, what you did (voyage
specifics), what you found, and your theory – to include the specifics of the steps of your theories
and supporting evidence you presented. Be sure to include drawings of some of the adaptations you
investigated. Your letter should be at least one page in length, not including drawings. Use a
separate sheet of lined paper for this portion of the test. 1st person account – here are some facts to
work into your account. Born the same day, and with minutes of, the birth of Abraham Lincoln in
1809.. Had an interest in the natural world as a youngster, but did not focus on studies, and
dropped out of med school without telling his doctor dad, hated to watch the cruel surgery on a
screaming woman. At about the time he was figuring out what to do with his life, an opportunity
to go on the ship HMS Beagle, as a Naturalist, but more to be a traveling companion to the captain
than because the Navy wanted a Naturalist. The Beagle had to chart the coast of South America,
the trip was expected to take two years, took almost 5 years. Visited the Amazon, trekked in
South American by horseback, picked up a sickness there, that would bother him for his whole life,
gastrointestinal difficulties, including passing gas a bit,. Collected lots of specimens, thank you
Dad, for paying to them to be placed in barrels and shipped home. When the ship went to the
Galapagos Islands off the coast of Ecuador, was one of the first two people off the small boat.
Was amazed at how unfrightened the birds and other creatures were, he could catch birds with his
bare hands. Notices how the birds and tortoises were different from one island to the next, but did
not have any “aha!” moment while on the islands for about 5 weeks. Still, collected a fair amount
of specimens, and fortunately, had someone label the islands from which they came. Returned to
England after nearly 5 years, and thanks to the barrels of specimens sent, already had an excellent
reputation as a naturalist. Decided it was time to marry, and married his first cousin, Emma
Wedgewood, whose dad had a small fortune from starting Wedgewood China, so Charles and
Emma had enough money not to have to work or worry about money. Was curious about how
dogs and horses got selectively bred, and also curious about sea shells (barnacles), so studied them
for the next 10 years, while he also slowly arrived at his theory of evolution. Described his theory
in a letter to a buddy, long before he published. Possibly because of his worries about his health
and flatulence, did not attend a ton of meetings, did a lot of his work by correspondence.
Corresponded with another naturalist, Alfred Russell Wallace, who had sent a note to Darwin
providing an explanation for why brightly colored organisms (such as caterpillars) had their bright
colors, in response to an article by Darwin where he wondered about it. Darwin encouraged
Wallace with his explorations. Meanwhile, Darwin worried that his theory about evolution by
natural selection, not by some divine guidance, would bother his very religious wife, and he still
had doubts whether he had collected enough evidence, so he did not publish. Then, out of the
blue, and from Indonesia, Wallace sent Darwin a manuscript asking if Darwin could assist him by
forwarding it to the leading science journal of the day. Darwin was stunned to see that Wallace
was setting forth the same theory of evolution by natural selection that Darwin had, one that he
had written about in 2 private letters to a friend, but had never published, in part because of
concerns it would stress his wife. What to do? Darwin decided that the honorable thing to do was
to forward Wallace’s paper ALONG with one from Darwin saying the same thing, and to work
helter skelter to finish his book, “On the Origin of Species” . Which he did, in 1859 (not long after
the Lincoln/Douglas debates.) Initially, the book was very well accepted, but in time some
religious people took issue with it. The book never addressed the evolution of humans, but many
people assumed that it stated that humans had evolved from apes. Big debate of the day, back
then, still brings forth arguments, but Darwin’s book and theory stands today as a landmark work
of science, with evolution as a leading theory that explains life.
12. What is a species? A group of similar organisms that, when they breed, produce
fertile offspring.
15. The theory of evolution can be explained in part by changes in an organism’s DNA known
as _mutations, when favorable they are called adaptations.
16. An example of separation as a step leading to the evolution of a new species is the
following: a tall mountain range rising up to separate populations of an organism.