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Name _______________________ due date __________
CHAPTER 5: THE PROCESS OF EVOLUTION
I. Natural Selection
A. Charles Darwin was the first to compile persuasive evidence supporting evolution
1. __________ is genetic change in a population over time
2. Darwin’s __________ transformed the natural sciences and serves as the basis of all
biological research today
3. Darwin served as a __________ on the British naval ship the H. M. S. Beagle
a. The __________ sailed for five years from England to South America to make naval
maps
b. Darwin observed __________, collected samples of new plants and animals, and wrote
about places and organisms few people had seen
4. Darwin’s most unique findings were the diversity and uniqueness of organisms on the
__________ Islands, 1000 km of the coast of South America.
a. After comparing animals and animal fossils from the different __________, he observed
that they were different from organisms on the __________ mainland
b. Darwin reasoned that some of the species might have originated in South America but
__________ to be different
c. Darwin found enormous __________ on all Galapagos Islands
d. Tortoises had __________-__________ shells and __________necks where they ate
low-growing plants
e. They had __________-__________shells and __________ necks where they ate highgrowing cactus
f. Darwin concluded that the different tortoises descended from a common ancestral in
__________South America, but each evolved to fit its unique environment
g. Darwin observed that finches, on different islands had distinct __________sizes and
shapes
h. He concluded that the __________, like tortoises, had common South American
ancestor, but that they became different to suit the different island habitats
i.
__________ __________occurs when people breed plants and animals, such as
vegetables or cows, to produce desired traits
j.
Selective breeding does not produce new __________; all dogs can still have offspring
with their common ancestor the wolf
B. Darwin’s theory of natural selection states the organisms with traits that allow them to survive in a
particular environments pass on traits that could lead to new species
1. __________ __________is the creation of a diversity of traits through gamete formation
a. A harmful __________ may cause an organism to die; a beneficial trait will be passed on
to the next __________
b. Genetic variation is necessary for __________ by natural selection to occur
2. Animals often produce __________ offspring than available resources can support
a. Thomas Malthus described this “struggle to survive” among the human __________
b. Darwin applied Malthus’ idea to __________ for survival among individuals in a species
c. Organisms best prepared for living in specific habitats will survive and __________, and
their __________ will be best able to survive and reproduce as well
3. New __________can develop if organisms with common ancestors become __________ and
natural selection causes them to differentiate in response to different environments
a. Inherited traits that increase an organism’s chance of surviving and reproducing in a
particular environment are called __________
b. Darwin’s theory of evolution by natural selection includes four steps: __________,
variation/competition, inherited variation, and natural selection
c. Populations evolve as favorable __________ in a particular environments spread through
generations
4. After 20 years, Darwin published The __________ of the Species by Natural Selection.
a. Darwin developed the idea that all organisms have “descended with __________” from
common ancestors
b. Darwin believed that evolution by natural selection explains the __________ of modern
organisms
II. Adaptations and Extinction
A. Organism evolve __________ for specific environments through natural selection
1. Adaptations are the result of a long process by which __________ are passed from one
generation to another
a. people may __________the word adaptation, believing adaptations occur within a
generation and/or are __________ rather that naturally selected
b. Not all inherited traits are adaptations; __________ traits may stay in a population is
they are __________ to beneficial ones
c. Positive traits may help an organism to __________; negative traits may cause it to die
off
B. Two types of adaptations are structural adaptations and behavioral adaptations
1. __________ __________ are aspects of the physical body that help and organism survive
and reproduce
a. __________, or blending in with one’s surroundings, is a type of structural adaptation
b. Lizards change __________ to blend in with their surroundings; __________ animals
sometimes have camouflage coloration when they are more vulnerable to predators
c. __________ is when one species, a species looks or behaves like another
d. Some __________ organisms look like other dangerous or poisonous organisms to
discourage predators
e. In another type of mimicry, a species fools its __________ by looking inviting or familiar
2. __________ __________, also called instincts, depend on the actions of an organism
a. Clapper rails build their__________ so that they will rise and fall with the wetland tides
b. The male satin bower __________ its nest to attract a female mate
C. A species becomes __________ when all of the individuals of that species are wiped out
1. Several major events in __________ of the Earth have lead to extinctions
2. Major __________ of extinction are habitat destruction, loss of genetic diversity, and
introduction of exotic species
a. Habitat for plants and animals __________ as humans develop and occupy more space
b. The fewer the individuals left of a species, the less __________ __________ in the
population
c. A species is __________ if there are so few individuals that lack of genetic diversity
could lead to species extinction
d. The introduction of __________ species has few __________, it can out-compete
native species and push them toward extinction
3. If __________ environmental change occurs when only small population of a species exist,
lack of __________ __________ could lead to extinction relatively quickly.