Download Evolution Study Guide 2012

Evolution Study Guide 2012
Although the arm of a human and the flipper of a dolphin serve different functions, there
is great similarity in their structures and developments. This similarity is known as
a. Homology
b. Homologous
c. Homogeneous
d. Homogenesis
e. None of the above.
answer: a. Homology is the structural similarity based on common descent. The flipper of
a dolphin and the arm of a human are similar in their structure, yet dolphins use their
flippers to swim while humans use their arms for various functions.
Free Response
Charles Darwin proposed that evolution by natural selection was the basis for the
differences that he saw in similar organisms as he traveled and collected specimens in
South America and on the Galapagos Islands.
a)Explain the theory of evolution by natural selection as presented by Darwin.
b) Explain how natural selection and the formation of insecticide-resistant insects or
antibiotic resistant bacteria are related.
Answer: a) Natural selection is the tendency of organisms that have favorable
adaptations to their environment to survive and become the parents of the next
generation. Evolution occurs when natural selection results in changes in allele
frequencies in a generation. These species have an extra advantage over species that are
not able to adapt and survive.
b) Insecticides and antibiotic are made to kill one type of bacteria or organism that is
creating a problem. As insecticides are only created for one type of organism, some of the
residue is still alive. This means that some of the remaining living organisms have a
certain advantage, which means that the next generation will be able to stay alive and
carry that favorable adaptation for future generations. This results in the creation of
insecticides or antibodies that are able to affect those organism that were able to stay
alive.
1. The Hardy – Weinberg principle gives one what information?
a) That inheritance is not the sole factor of the lack of evolutionary
change in a large population
1
b) Why dominant alleles are not necessarily more common than
recessive alleles
c) The expectation one can uphold for a sexually reproducing
population
d) All of the above
Answer: D
Q. Explain what is the founder effect and create an exemplary circumstance that depicts
the process and genetic results of this specific form of genetic drift on a species of
migratory birds.
Answer Open Ended:
The founder effect is when a few individuals form a larger population separate
from the rest of the main group of individuals, brining with them only a small fraction of
the genetic variation previously existing in the original population. As a result, the alleles
among the future generations of the separated individuals will be different from the allele
frequencies expressed in the parent population as the alleles expressed are entirely
derived from the original colonizers, or founders.
An example of the founder effect involving migratory birds could be one such as
this:
A flock of Blue Jays was following its migratory path to a location of warmer
climate when, on its way it was confronted by a heavy storm. As a result a small group of
individuals ended up lost and separated from the main flock. In continuing their travels,
the separated individuals settled in a different location than their original destination.
However, the small group of Blue Jays remained in the new location and ensued with
reproduction, eventually perpetuating a new population within several generations. In this
example of genetic drift, the population has experienced the founder effect as the only
alleles of the decedents in the new population are from the founders – the individuals
2
All of the following are part of Darwin’s theory of natural selection EXCEPT
A. Populations tend to overpopulate
B. In any population, there is an unequal ability among individuals to survive and
reproduce
C. Only the best-fit individuals survive and get to pass on their genes
D. Overpopulation leads to a struggle for existence
E. Organisms change in response to a need in the environment
Answer: E- This idea is actually from Lamarck, not Darwin.
Open Ended
What pattern of evolution does this image depict? Describe that pattern, and relate it to
Darwin’s finches.
Answer: This image depicts adaptive radiation. Adaptive radiation is the emergence of
numerous species from a single common ancestor introduced into an environment. These
many related species come from one or a few ancestral species in a relatively short period
of time. Darwin’s finches are the prime example of adaptive radiation. While Darwin
was on the Galapagos Islands, he discovered 14 species of finches that each filled a
different ecological niche. Some lived on the ground, while others were adapted for life
in the trees. Also, their beaks were adapted for different diets, such as seeds, buds, and
insects. All of these finches evolved from a single ancestral species, and radiated to fill
14 different niches, making them a primary example of adaptive radiation.
1. In a population of butterflies, the color brown (B) is dominant over the color
white (b) and, 40% of all butterflies are white. Given this information, calculate
the following:
A) The percentage of butterflies in the population that are heterozygous.
B) The frequency of homozygous dominant individuals.
3
a) Heterozygous: 0.60 Homozygous Dominant: 0.40
b) Heterozygous: 0.40 Homozygous Dominant: 0.60
c) Heterozygous: 0.14 Homozygous Dominant: 0.47
d) Heterozygous: 0.47 Homozygous Dominant:0.14
The Correct answer is D. Using the Hardy Weinberg model, q2 would be 0.4
(40% white). Therefore, q=0.63. Since p+q= 1, then p= 0.37. The percentage of
Heterozygous genes is 2pq, therefore it is 0.47. Finally, the percent of
homozygous dominant genes is p2 so it would be 0.14 (0.37)2 .
2. a) Of the cladograms shown below, which one shows a different evolutionary
history from the others?
b) Using this chart, make a cladogram for the characters.
Derived Characters
segmented jaws hair placenta multicellular limbs
kangaroo
earthworm
amoeba
lizard
cat
sponge
salmon
+
+
+
+
+
+
+
+
+
+
+
-
+
-
+
+
+
+
+
+
+
+
+
-
Answer:
a) The correct answer is Cladogram 3. In Cladograms 1, 2, and 4, C shares the
most recent common ancestor with D, but in Cladogram 3, B and C share the
most recent common ancestor.
4
b)
2)
a) Use these characteristics of students to construct a dichotomous key.
b) Which two students are considered to be most similar? What can be inferred
about their similarities?
c) How do taxonomists use dichotomous keys to further their research in
evolution?
Student
Sex (M/F)
1
2
3
F
M
F
Height
(meters)
1.5
1.7
1.6
Eye Color
Skin color
Brown
Brown
Blue
Brown
Brown
Tan
Answers: 2a.
1a. Male
1
1b. Female
2a. Eye color Brown
2b. Eye color Blue
3a. Height is 1.5 m
3b. Heigh is 1.6 m
4a. Skin color is tan
3
4b. Skin color is brown
Student
2
3
3
4
4
Student
Student 2
B) Students 2 and 3 are most similar which means they have the most similar
gene sequences but are arranged differently.
5
C) Taxonomists can benefit from dichotomous keys by discovering unknown
species within the same species by related characteristics and gradually
narrowing the characteristics down.
Q: In a community, there is a bird that has three different varieties of beaks: small,
medium, and large. In the community, the birds eat tiny seeds, small acorns, and big,
hard walnuts. Birds with small, needlelike beaks eat the seeds, the birds with mediumsized beaks eat small acorns, and birds with large beaks eat the walnuts. Over the course
of 100 years, oak trees started to die off, and all acorns were eventually eaten. The small
and large-beaks birds still kept their diets, but the medium-beaked birds were too big to
eat the seeds and too weak to eat the walnuts. As a result, the birds with medium-sized
beaks eventually decreased in numbers. This is an example of what type of natural
selection:
A: Stabilizing selection
B: Disruptive selection
C: Convergent selection
D: Directional selection
The answer is B because disruptive selection is when species with intermediate features
do not survive in their habitats due to natural selection. This causes two extremes to
peak; in this case, the small-beaked birds and the large-beaked birds.
Open Ended
Q: The aardvark, anteater, and pangolin are similar species that live in Africa, South
America, and Asia, respectively. The similar species have not descended from a common
ancestor. What is this phenomenon and why does it occur?
A: This occurrence among the three species is called convergent evolution. This occurs
when different populations live in areas with similar conditions. In these areas, natural
selection will have similar effects on the species. This is why the species eventually have
similar features.
All the following are true of homologous structures except
A)
B)
C)
D)
E)
They demonstrate common ancestry
An example is the wing of a bat and a person’s arm
An example is the wing of a bat and a wing of a fly
They are not the same thing as analogous structures
An example is a whale’s lateral fin and a person’s arm
Answer: C
Explanation:
6
Although the wing of a bat and a fly’s wing have the same function, they are not alike
structurally. Therefore, they are analogous structures, not homologous. They do not
demonstrate a common ancestry. They are examples of divergent evolution.
Open Ended Question
1.
2.
3.
Identify the type of natural selection illustrated by each graph. Explain each type.
Answer:
1. Stabilizing selection
2. Directional selection
3. Disruptive selection
Stabilizing selection eliminates the number of extremes and favors the more
common intermediate forms. Mutant forms are weeded out this way. Disruptive
selection increases the numbers of extreme types in a population at the expense
of intermediate forms. It results in balanced polymorphism, where two or more
phenotypes coexist in a population. Over great lengths of time, disruptive
selection can result in the formation of an entirely new species. Directional
7
selection develops from changing environmental conditions, where one genotype
replaces another in a gene pool.
Multiple-Choice Question
Which of the following factors mayaffect genetic equilibrium within a population?
A. Initial allele frequencies
B. Presence of natural selection
C. Migration
D. Both B and C
The answer is (D) because both B and Care factors of Hardy-Weinberg
equilibrium.
The five things necessary to have Hardy-Weinbergequilibrium are large
population size, random mating, no natural selection, nomigration, and no net
mutations. (A) isnot an acceptable answer because allele frequencies will not
effect geneticequilibrium if all five Hardy-Weinberg conditions are met.
Open-Ended Question
Explain the difference betweenallopatric speciation and sympatric
speciation. Which one occurs mostly among plants; which one occurs mostly
amonganimals.
Answer: Allopatric speciation occurs when one population becomes
geographically isolatedfrom the rest of the species and evolves on its own. This
is mostly among animals. Sympatric speciation occurs when two populationsof
the same species diverge in the same physical location. This type of speciation
happens mostly amongplants.
1. Two different species of birds had been spotted. Although the two birds are hard to
differentiate, they have different mating songs. When the two birds tried to mate, the
male bird refused because the female bird’s song had a lower pitch. This is an
example of what kind of prezygotic barrier?
A. Temporal Isolation
B. Behavioral Isolation
C. Gametic Isolation
D. Mechanical Isolation
8
The answer is (B) because the example illustrates how the two species of birds can’t mate
because of their distinctive songs before mating, defining behavioral isolation. Their
differences in mating behaviors prevented the two birds from coming together.
1. If a population rapidly decreases in size, genetic drift can occur in the small population
of survivors and many allele frequencies may be different when the population increases
again. A small population of a particular type of bird lives in a forest in New Jersey. Half
of the birds have brown feathers and the other half have blue. Based on the preceding
information which of the choices below is an example of a bottle neck?
A. Deforestation is making it hard for the entire population of birds to stay in the
forest so some of them flee to a new habitat. In the new habitat the next generation
of birds have mostly brown feathers.
B. Deforestation is depleting the food supply in the bird population and most of the
birds die out. The resulting next generation has mostly blue feathers.
C. In the forest the birds live happily with the existence of just one predator. In the
next generation mostly brown birds are seen.
D. The next generation of birds is an even amount of blue feathers and brown
feathers.
Answer: The answer is B. Answer A is an example of the founder effect, while C is
natural selection, and D is an example of a healthy population with no predators.
1. In a population of 3000 birds, 625 of them have a recessive gene that gives them
orange colored beaks.
A. How many birds have the homozygous dominant trait of yellow beaks?
B. How many are heterozygous?
Answers:
A. q^2=625/3000; q^2=0.2083; q=0.4564 1-q=p; p=0.5436;p^2=0.2955;
homozygous dominant=886 birds
B. 2pq=1-p^2-q^2; 2pq=0.4962; heterozygous=1489
9
10