Download Unit 3 Review Answer Key 1. Define the following terms: a

Unit 3 Review
Answer Key
1. Define the following terms:
a. Adaptation is a trait with a current functional role in the life history of an
organism that is maintained and evolved by means of natural selection. An
adaptation refers to both the current state of being adapted to the dynamic
evolutionary process that leads to the adaptation. Adaptations contribute to the
fitness and survival of individuals.
b. Lamarckism is an idea that an organism can pass on characteristics that it
acquired during its lifetime to its offspring (also known as heritability of acquired
characteristics or soft inheritance). It is named after the French biologist JeanBaptiste Lamarck, who incorporated the action of soft inheritance into his
evolutionary theories.
c. Fitness is the ability to both survive and reproduce within the current
environment and can be related to genotype or phenotype.
d. Plastic phenotype (phenotypic plasticity) is the ability of an organism to change
its phenotype in response to changes in the environment.
e. Sexual selection is a special type of natural selection in which the sexes
acquire distinct forms either because the members of one sex choose mates with
particular features or because in the competition for mates among the members
of one sex only those with certain traits succeed. Many animals develop features
whose function is not to help individuals survive, but to help them to maximize
their reproductive success. This can be realized in two different ways: 1) by
making themselves attractive to the opposite sex (intersexual selection between
the sexes); or 2) by intimidating, deterring, or defeating same-sex rivals
(intrasexual selection within a given sex).
f. Direct benefits hypothesis is when one sex chooses individuals of the other sex
that can provide direct benefits to that individual and can affect the choosing sex
directly. For example, by choosing an individual of the other sex that can provide
benefits, one sex increases its own lifetime reproductive output through better
territory for feeding, rearing, and raising young.
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g. Sexy son hypothesis is when females choose males whose genes will produce
male offspring with the best chance of reproductive success. In particular, the
sexy son hypothesis implies that a potential mate's capacity as a caregiver or any
other direct benefits the male can offer the female (e.g. nuptial gifts, good
territory, etc.) are irrelevant to his value as the potential father of the female's
offspring. What matters are her sexy son's future breeding successes (like that
of his promiscuous father) in creating large numbers of offspring that carry copies
of the female's genes.
h. Good genes hypothesis is when one sex chooses individuals of the other sex
for genes that enable it to develop impressive ornaments or fighting ability. For
some examples, the individual may simply show off greater disease resistance,
greater ability to find forage, or a more efficient metabolism, which are features
that also benefit the choosing sex.
i. Ernst Mayr was one of the twentieth century's leading evolutionary biologists.
He was also a renowned taxonomist, tropical explorer, ornithologist, and historian
of science. His work contributed to the conceptual revolution that led to the
modern evolutionary synthesis of Mendelian genetics, systematics, and
Darwinian evolution, and to the development of the biological species concept.
j. Theodosius Dobzhansky was a prominent geneticist and evolutionary biologist
as well as a central figure in the field of evolutionary biology for his work in
shaping the unifying modern evolutionary synthesis.
2. A population of grasshoppers in the Kansas prairie has two color phenotypes: green
and brown. Typically, the prairie receives adequate water to maintain healthy, green
grass. Assume a bird that eats grasshoppers moves into the prairie. How will this affect
natural selection of the grasshoppers?
A. The green phenotype should be more easily seen by the predator and decrease in
frequency.
B. The brown phenotype should be more easily seen by the predator and decrease in
frequency.
C. Both green and brown grasshoppers should be eaten and there relative numbers
should remain constant.
D. Predation will cause the brown grasshoppers to mutate into green grasshoppers.
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3. Using the example above, which type of selection is most likely to occur?
A. Directional
B. Stabilizing
C. Disruptive
D. None of the above
4. Which of the following would you predict would evolve in guppies taken from streams
with predators that key in on prey color and put into streams lacking predators?
A. Guppies would become more colorful.
B. Guppies would become less colorful.
C. Guppies would not change in coloration.
D. Guppies would evolve to have females prefer less colorful males
E. Guppies would evolve to have females prefer even more colorful males.
5. What determines which traits will be passed on to the next generation in the greatest
frequency?
A. Mendelian genetics of the trait
B. Random mutations in the trait
C. The species in which the trait occurs
D. The fit of the trait to the environment
E. Non-random mutations in the trait
6. Natural selection is BEST described as which of the following?
A. Natural selection allows for a generation of new traits that better suit the species.
B. Natural selection increases the perfection of a species.
C. Natural selection works on existing variation of traits to favor those better suited to
the organism's environment.
D. Natural selection causes the death of a significant proportion of the population.
E. Natural selection drives the species toward an eventual endpoint sometime in the
future.
7. If the weather in Richmond, Virginia, changed to very cold (snow on the ground 8
months of each year) over the next few years, what change might occur?
A. The cold weather would cause a mutation in squirrels, which would cause their fur to
be white.
B. If a mutation occurred which caused white fur to develop on squirrels, such white
squirrels would have a better chance to survive and produce more offspring with the
characteristic.
C. Evolution would definitely occur, resulting in white squirrels.
D. Natural selection would cause a new genotype to appear in the population of
squirrels, resulting in squirrels with white fur.
E. Natural selection would not permit such climatic changes.
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8. Which of the following actually evolves?
A. Individuals
B. Populations
C. Communities
D. Mutations
9. In order for speciation to occur, which of the following must be true?
A. There must be a barrier to gene flow between populations
B. A population must be dispersed to an island.
C. The original population must become polyploid.
D. There must be some genetic variability in the population
E. Both A and D
F. Both A and B
10. Fill in the blanks. In Lamarck’s theory of evolution ___________ changed over
_____________, compared to Darwin’s theory of evolution where ________________
changed over __________________.
A. Populations, generations, individuals, lifetime
B. Species, generations, populations, generations
C. Individuals, generations, individuals, lifetime
D. Individuals, lifetime, populations, generations
11. Can an organism’s fitness be directly related to its immediate environment? Why, or
why not? Yes. A fit individual has the ability to both survive and reproduce within the
current environment. This can be related to genotype or phenotype. Therefore, if an
environment changes individuals that were not as fit (or successful in surviving and
reproducing) before, then the individuals may be more fit in the new environment (and
will therefore survive and reproduce in greater numbers). The peppered moth evolution
is an example (http://en.wikipedia.org/wiki/Peppered_moth_evolution).
12. What were the main branches of biology that were drawn together through the
evolutionary synthesis to support evolutionary theory? Genetics, cytology, systematics,
botany, morphology, ecology and paleontology
13. We currently see an irregular, branching, and non-directional pattern in the fossil
record.
Does this support evolutionary theory? Why, or why not? Yes. Evolution is based on
random biotic and abiotic events (such as mutation, environmental changes, and so
forth), affecting the current gene pool. Therefore, organisms are not unchanging endproducts and are not striving to reach an evolutionary “goal” or end point. Species in
the history of evolution are expected to change randomly at differing rates and
persisting at varying lengths.
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14. Draw a graph representing the concepts below.
a. Directional selection
b. Stabilizing selection
c. Disruptive selection
(graph adapted from: http://en.wikipedia.org/wiki/Directional_selection)
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