Download A. Directional Selection

NG Biology Standard 2B
Natural Selection
Scappoose HS
Darlak C-2
Name ______________________
Period: _____
Textbook:
Biology: The Dynamics of Life. 2002.
Chapter 15.1 (pps. 400-404)
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Standard 2B Evolutionary Processes

HS-LS4-2
HS-LS4-3
HS-LS4-4


Construct an explanation based on evidence that the process of evolution primarily results from four factors: (1) the potential for a species to
increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited
resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment.
Apply concepts of statistics and probability to support explanations that organisms with an advantageous heritable trait tend to increase in
proportion to organisms lacking this trait.
Construct an explanation based on evidence for how natural selection leads to adaptation of populations.
Learning Targets
Beginning Proficient-1
I can identify and analyze
the four steps of Natural
Selection.
I cannot consistently
identify the four steps of
Natural Selection in a
ways that demonstrates
my understanding of this
process.
I cannot identify the
three modes of Natural
Selection with any
consistency.
I can identify and analyze
the three modes of
Natural Selection.
I can identify and analyze
how behavioral,
physiological and
structural adaptations
emerge as a result of
Natural Selection.
Essential Questions:
How can Natural Selection lead to so many variations?
How can unrelated organisms look so similar?
How fast can species evolve?
I cannot identify if an
adaptation is structural,
behavioral or
physiological with any
consistency.
Developing Proficient-2
Proficient-3
Highly Proficient-4
I can list and/or identify the four
steps of Natural Selection with
little to no errors.
I can identify the four steps of
Natural Selection in a real life
scenario with little to no errors.
I can create a scenario regarding
natural selection that includes
abiotic or biotic influences and a
specific adaptation that results with
only minor errors.
I can identify the three modes of
Natural Selection with little to no
errors. (Disruptional, Stabilizing,
Directional) with little to no
errors.
I can identify if an adaptation is
structural, behavioral, or
physiological with little to no
error.
In a scenario I can determine the
type of Natural Selection that is
occurring with little to no errors.
In a scenario I can accurately graph
the distribution of the population
before disruption and distribution of
the population after disruption.
I can identify if an adaptation is
physiological, structural or
behavior in a real life scenario
with little to no errors.
I can justify why I believe the
adaptation is classified as
behavioral, structural or
physiological in a real life scenario.
Vocabulary
Adaptation
Evolutionary Fitness
Stabilizing Selection
Artificial Selection
Natural Selection
Behavioral Adaptation
Physiological Adaptation
2
Disruptional Selection
Sexual Selection
Directional Selection
Structural Adaptation
Learning Targets
Standard 2B Evolutionary Processes
I can identify and analyze
the four steps of Natural
Selection.
I can identify and analyze
the three modes of Natural
Selection.


I can explain what happens and give examples of the four steps of natural selection.
I can create a scenario using the four steps of natural selection to show how a population changes over time.




I can identify and analyze
how behavioral,
physiological and structural
adaptations emerge as a
result of Natural Selection.




I can identify directional selection when given a graph or description of how a population has changed.
I can identify disruptional selection when given a graph or description of how a population has changed.
I can identify stabilizing selection when given a graph or description of how a population has changed.
In a scenario, I can accurately graph the distribution of the population before disruption and distribution of the
population after disruption.
I can define and give examples of behavioral adaptations.
I can define and give examples of physiological adaptations.
I can define and give examples of structural adaptations.
If given a scenario, I can identify what type of adaptation is being described.
Natural Selection Standard Outline
I. Postulates of Natural Selection
Darwin’s Observations:
1. Overproduction
2. Variation
Darwin’s Inferences:
3. Selection
4. Adaptations
II. Modes of Selection
A. Directional- selection of one extreme
B. Stabilizing- selection of the mean/average type
C. Disruptive- selection of both extremes
III. Types of Adaptations
1. Structural- anatomical
2. Physiological- metabolic
3. Behavioral- what it does
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Theory of Natural Selection vs Theory of Acquired Characteristics
Who Proposed it?
What is the theory?
Give an example scenario:
Choose one of the following
animals and their trait and
explain how each theory
would explain the
acquisition of that trait in
the population:
 How Eagles got great
eyesight
 How Beavers got sharp
teeth
 How tigers got their
stripes
Theory of Natural Selection
Theory of Acquired Characterisitcs
1.
1.
2.
2.
3.
3.
4.
4.
According to Natural
Selection…
According to Acquired
Characteristics…
Who thought this? Lamarck, Darwin, or both of them?
1. Organisms have changed over time.
2. Organisms changed because they wanted to survive.
3. There was variation in a population.
4. Certain traits helped organisms survive and reproduce better than other
organisms without those traits.
5. Organisms can never become extinct.
6. The environment had something to do with why organisms changed.
7. Parents are able to pass on at least some of their traits to their offspring.
8. Parents are only able to pass on traits that they were born with.
9. Organisms could decide to change something about their body and pass on
that change to their offspring.
10. Organisms are still changing.
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I. Postulates of Natural Selection
Read the following information about the elephant population of Queen Elizabeth
National Park in Uganda, Africa. Then fill in the table on the following page.
Normally, nearly all African elephants, male and female, have tusks.
In 1930, only 1 percent of the elephant population in Queen Elizabeth
National Park was tuskless because of a rare genetic mutation. By
1963, there were 3,500 elephants in the park. In the 1970s, a civil war
began in Uganda. Much of the wildlife was killed for food, and
poachers killed elephants for their ivory tusks. By 1992, the elephant
population had dropped to about 200. But by 1998, the population had
increased to 1,200. A survey in 1998 revealed that as many as 30
percent of the adult elephants did not have tusks. Ugandan wildlife
officials also noted a decline in poaching.
1. ___________________________
- Individuals that are better
able to cope with the
challenges of their environment
tend to leave more offspring
than those less suited.
Example:
2. ___________________________
- All species have genetic
variation.
Example:
3. ___________________________
- Living things face many
challenges in the struggle to
exist. Individuals of species
often compete with one
another to survive.
Example:
4. ___________________________
- The characteristics of the
individuals best suited to a
particular environment tend to
increase in a population over
time.
Example:
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Darwin’s Natural Selection Worksheet
Read the following situations below and identify the 4 points of Darwin’s natural selection.
1)There are 2 types of worms: worms that eat at night (nocturnal) and worms that eat
during the day (diurnal). The birds eat during the day and seem to be eating ONLY the
diurnal worms. The nocturnal worms are in their burrows during this time. Each spring
when the worms reproduce, they have about 500 babies but only 100 of these 500 ever
become old enough to reproduce.
a. What worm has natural selection selected AGAINST? ___________ FOR? _____________
Darwin's 4 points: Identify the 4 points in the scenario above.
A. More offspring are produced than survive._________________________________________
B. Population has variations. _______________________________________________________
C. Those with favorable traits survive.________________________________________________
D. Population is made up of individuals with favorable traits._____________________________
2) There are 3 types of polar bears: ones with thick coats, ones with thin coats and
ones with medium coats. It is fall, soon to be winter. The temperatures are
dropping rapidly and the bears must be kept warm, or they will freeze to death.
Many of the bears have had ~2 cubs each but due to the extreme temperatures,
many mothers only have one cub left.
a. What bear will natural selection select AGAINST? _______________ FOR? _________________
Darwin's 4 points: Identify the 4 points in the scenario above.
A. More offspring are produced than survive._________________________________________
B. Population has variations. _______________________________________________________
C. Those with favorable traits survive.________________________________________________
D. Population is made up of individuals with favorable traits._____________________________
3) In ostriches, there are 2 types: ones that run fast and those that run slowly. The
fast birds can reach up to 40 miles an hour. Jackals love to eat ostrich, and they can
reach speeds of up to 35-40 miles per hour. A flock of ostrich will lay ~ 10 eggs (each mother
only lays 1), but many rodents break into the eggs and eat the fetus before they hatch.
a. What ostrich will natural selection select AGAINST? ________________ FOR? ______________
Darwin's 4 points: Identify the 4 points in the scenario above.
A. More offspring are produced than survive._________________________________________
B. Population has variations. _______________________________________________________
C. Those with favorable traits survive.________________________________________________
D. Population is made up of individuals with favorable traits._____________________________
4) There are two types of rabbits: those that strictly eat grass and those that strictly eat berries and
flowers. A drought occurs one year, and the plants have difficulty producing any extras (flowers,
berries, etc.). They can only try and keep themselves green. The rabbits have had babies all year long
but many are eaten by foxes or hawks. Due to the drought, many have starved to death.
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a. What rabbit will natural selection select AGAINST? ______________ FOR?_________________
Darwin's 4 points: Identify the 4 points in the scenario above.
A. More offspring are produced than survive._________________________________________
B. Population has variations. _______________________________________________________
C. Those with favorable traits survive.________________________________________________
D. Population is made up of individuals with favorable traits._____________________________
5) Bob believes that giraffes have long necks because they have stretched their necks to try
and reach food that is high in trees. Since the parent had stretched its neck, it passed the long
neck on to its offspring. Ryan believes that giraffes have long necks because the ones with long
necks were able to reach the food, and those with short necks could not and died. The long
necked giraffes reproduced, and soon all of the giraffes had long necks.
a. Who thinks like Lamarck? _________________________________________________
b. Who thinks like Darwin? __________________________________________________
II.
Modes of Selection
A. Directional Selection
B. Stabilizing Selection
C. Disruptive Selection
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Types of Natural Selection
1. Stabilizing Selection-- The extremes are selected against.
Example: Too big or too small selected against.
2. Disruptive selection-- The extremes are both selected for.
Example: Very light and very dark are selected for.
3. Directional selection-- One extreme value is selected for.
Example: A longer trunk is more successful.
Read the examples below. Decide which type of selection is
described and create a graph to support your decision.
1. The weight of human babies tends to be between 5 and 9 lbs. Babies smaller than 5 lbs are at risk at
dying from being premature. Babies larger than 9 lbs can cause difficulties for the mother during
childbirth.
2. Onyx, a species of antelope, are very fast runners. The cheetah is their main predator. Slower Onyx
are often the first to get captured while the faster individuals can escape.
3. A species of butterfly called the YingYang is found on the Island of Bermuda. There are two distinct
color patterns of this butterfly, one is very light and the other is very dark. The white butterflies live
in the meadows of Lace bushes which have very light colored leaves and flowers. The dark
butterflies live in the forested areas of the island on the trunks of the Barosa tree. This tree is known
for its very dark bark.
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4. Red-eyed tree frog eggs take around 2-3 weeks to develop. These tree frogs lay their eggs in water
pockets of epiphytes (plants that live on other plants). Over the last 25 years, the average time it
takes for the water pocket puddles to dry up has been decreasing due to an increase in temperature
and a decrease on rainfall.
5. The Redbud flower lives along the roadside; the flower varies greatly in size. They range in flower
size varies from 1 to 6 inches across. Travelers often stop along the road to pick these flowers. They
often choose to pick the flowers around 4 inches across because the large flowers won’t fit in the
car and the small flowers aren’t as pretty.
6. The frilled lizard lives in the desert regions of Western Australia. These regions are very old where
the rocks have been eroding for many years; therefore there are only small rocks in this habitat.
Monitor lizards are predators of the frilled lizard. When the monitor lizard is hunting in an area,
lizards often take cover under rocks to hide from the Monitor lizard. Over time the Frilled lizards
that have survived attack from the monitor lizard are only the smaller Frilled lizards.
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III. Types of Adaptations –
See PowerPoint “NG 3B Adaptation Notes & Assignment” on Class Website
Write a definition for each of the following and give an example.
1. Structural2. Physiological3. Behavioral-
Sort the Adaptations of Birds of New Zealand
Structural
Behavioral
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Physiological
Adaptation Assignment
1. Fill in definitions for the three types of adaptations on p. 7 of your packet.
2. Keep a list of all the different adaptations mentioned in the PowerPoint. Put each adaptation in the
correct column. Make sure to include examples of plant adaptations too.
3. Assignment
o Look at each picture.
o Choose 6 organisms (3 plants, 3 animals)
o Research, list, and explain as many structural, behavioral, or physiological adaptations of the
organism that enhances its survival.
Animal Adaptations
Animal 1
Adaptations (Type and
Description)
How does each adaptation enhance survival?
Animal 2
Adaptations (Type and
Description)
How does each adaptation enhance survival?
Animal 3
Adaptations (Type and
Description)
How does each adaptation enhance survival?
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Plant Adaptations
Plant 1
Adaptations (Type and
Description)
How does each adaptation enhance
survival?
Plant 2
Adaptations (Type and
Description)
How does each adaptation enhance
survival?
Plant 3
Adaptations (Type and
Description)
How does each adaptation enhance
survival?
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Galapagos Natural Selection and Survival
Round 1: Creating the Parent Generation
Phenotypes:
Short-necked: 4
Long-necked: 4
Genotypes:
NN : 4
nn : 4
Allele Frequencies:
N: 8/16 = 0.5
n: 8/16 = 0.5
Creating the Parent Generation
RESULTS: The Parents
Phenotypes:
Short-necked :
Long- necked :
Genotypes:
NN :
Nn :
nn :
Allele Frequencies:
N:
/32 =
n:
/32 =
ROUND 2: Breeding the Parents
Breeding the Parents
RESULTS: The Children
Phenotypes:
Short-necked:
Long- necked :
Genotypes:
NN :
Nn :
nn :
Allele Frequencies:
N:
/32 =
n:
/32 =
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ROUND 3: Breeding the Children
(REMOVE 8 Brown )
Breeding the Children
RESULTS: The Grandchildren
Phenotypes:
Short-necked:
Long- necked :
Genotypes:
NN :
Nn :
nn :
Allele Frequencies:
N:
/32 =
n:
/32 =
ROUND 4: Breeding of the Grandchildren (REMOVE 8 Brown)
Breeding the Grandchildren
RESULTS:
The Great Grand-Children
Phenotypes:
Short-necked:
Long- necked :
Genotypes:
NN :
Nn :
nn :
Allele Frequencies:
N:
/32 =
n:
/32 =
Compare the dominant and recessive allele frequencies of the fourth generation tortoises (the great
grandchildren) with the second generation of tortoises (the children). What has happened to the number of
long-neck tortoises in the area?
What has happened to the number of short neck tortoises in the area? Why?
14
10 Examples of Natural Selection
http://dsc.discovery.com/tv-shows/curiosity/topics/10-examples-natural-selection.htm
Use the website above to explain 10 different examples of natural selection
Example
Summary
How did the population Change?
What type of adaptation(s)?
1. Peppered
Moths
2. Rat Snakes
3. Pesticideresistant
insects
4. Galapagos
Finches
5. Peacocks
6. Warrior Ants
7. Deer Mouse
8. Nylon eating
bacteria
9. Lizards
10. Humans
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NATURUAL SELECTION INTERNET LAB
Natural Selection Review
Go to http://ats.doit.wisc.edu/biology/ev/ns/ns.htm
1. Go to Topic 1: Defining Natural Selection
a. What does Darwin mean by “survival of the fittest”?
i. What type of selection is happening to the salamanders on the Island of Sardinia?
ii. Fill in the blanks:
In this population ___________________ and __________________ tongued salamanders
survived the best.
iii. Which type of salamander produced the most offspring on average?_______________
iv. Most of the salamanders in the next generation would probably have
______________tongues.
v. A fit individual is one that _________________ and ___________________.
b. Natural Selection isn’t random.
i. Namib Desert
Does the phenotype affect the plant’s fitness in this situation? ________________
Which phenotype is more likely to survive and reproduce? ___________________
ii. Wyoming
Does a bison’s phenotype affect its fitness in this situation?___________________
Which phenotype is more likely to survive and reproduce? ___________________
iii. Cambodia
Does this phenotype affect the male damselflies’ fitness in this situation? _______
Which phenotype is more likely to survive and reproduce? ___________________
c. Natural Selection doesn’t create variation.
i. Namib Desert
What was the selective pressure for these salamandars? _______________________
Could any of the salamandars grown a longer tongue to get the flies?_____________
What phenotype varied in this population of salamanders?_____________________
Explain how natural selection works on existing variations_______________________
______________________________________________________________________
d. Defining natural selection
Darwin discovered that populations_________________________ by the mechanism of natural
selection. Natural selection happens because __________________________differ in how well
they ____________________________and ______________________ based on how well
their_____________________ suit them for their _____________________.
2. Go to topic 2: The Genetic Basis of Variation
PLAY SOME FITNESS FEVER!
a. What mode of inheritance is LDH activity in the mummichog? _____________________
b. Which genptype has the highest fitness?___________Lowest?_____________________
c. In bacteria which free fitness card, helps the fitness the most?____________________
d. In ragworts, which free fitness card helps them the most?________________________
16
Natural Selection Lab- PhET Simulation
Pre-Lab Questions
1.
What variables can you influence in this lab?
2. Define what a genetic mutation is. How do genetic mutations happen? How often?
3.
What do the terms fitness and adaptation mean? What is the difference between the two?
4. What selection factors might affect an animal population besides the ones used in this lab?
Designing The Experiment
In this Lab you will be controlling the mutations and environment of a population of rabbits. Your will create four
hypotheses and design an experiment to test each one. Your hypothesis will follow the format where you fill in
the (...) with your own ideas and reasons.
I hypothesize that (select a rabbit phenotype) rabbits will be (more/ less) likely to survive under (type of selective
factor) within the (select type of environment) environment, because..... (explain how their trait will help them
to survive or not)
***You must make at least one hypothesis for each of the three different types of phenotype mutations***
For each experiment you must have a control (no mutation) and fill in the following chart
Experiment
and
Hypothesis
•
•
•
•
Pheno
type
Selective
Factor
CONTROL
Group
Initial Pop at F3
CONTROL
Group
Final
Population
Experiment
Group
Initial Pop at
F3
Experiment
Group
Final
Population
Conclusion/
Observation
For each of the experiments, begin by adding a friend and a mutation. Wait until the F3 generation before
adding the selective factor.
After adding the selective factor let the simulation run for another 3 or 4 generations.
Use the population numbers from the chart to get you numbers for the table, remember you can zoom in
and out on the chart to get more accurate reads.
Repeat for experiments 2, 3 and 4
Post-Lab Questions
1.
Based upon your evidence from the simulation what conclusion are you able to make about each of the
three different types of phenotypes in rabbits?
2. What happens to animals that cannot compete as well with other animals in the wild?
3.
Sometimes animals that are introduced into an area that they never lived in before out-compete and
endanger resident species, why do you think this happens?
4. If only one species is considered the "fittest", why do we still have so many variations among species? Why
do some birds have very long pointy beaks, while other birds have short flat beaks?
5.
How do you think diseases can affect natural selection?
6. How does this simulation mimic natural selection? In what ways does this simulation fail to represent the
process of natural selection?
17
Learning Targets
I can identify and
analyze the four
steps of Natural
Selection
I can identify and
analyze the three
modes of Natural
Selection.
I can identify and
analyze how
behavioral,
physiological and
structural
adaptations emerge
as a result of Natural
Selection.
Standard 2B Natural Selection
Scenario Essay
Score
 I can explain what happens and give examples of the four
steps of natural selection.
 I can create a scenario using the four steps of natural
selection to show how a population changes over time.
 I can describe how a population has changed by
directional, disruptional, or stabilizing selection.
 In a scenario, I can accurately graph the distribution of the
population before disruption and distribution of the
population after disruption.
 I can define and give examples of behavioral adaptations.
 I can define and give examples of physiological
adaptations.
 I can define and give examples of structural adaptations.
 I can create a scenario, describing how a specific type of
adaptation emerges as a result of natural selection.
/25
/25
/25
/5
/5
/85
 Conventions
 Intro and Conclusion
 Total
18
2B Natural Selection Pre-Test
Name:__________________________
Multiple Choice
Identify the choice that best completes the statement or answers the question.
1. Behavioral adaptations are _____________.
a. how an animals acts and behaves in order to stay alive.
b. physical features of an organism. c. the body’s
response to something in the environment .
2. Physiological adaptations are _______________.
a. how an organism acts and behaves in order to stay
alive. b. physical features of an organism that allows it
to survive. c. the body’s response to something in the
environment.
a. Physiological b. Behavioral c. Structural
7. Which step of natural selection is the is the example
illustrating?
3. Which step of natural selection is this example
illustrating?
a. overproduction b. adaptation c. selection
d. variation
a. Overproduction b. Variation c. Selection
d. Adaptation
8. Which step of natural selection is the example
illustrating?
4. Which type of adaptation is a polar bear’s thick layer of
fat? Is the adaptation from a biotic or abiotic selection
factor?
a. overproduction b. variation c. selection
d. adaptation
a. Physiological b. Behavioral c. Structural
5. Which step of natural selection is the below example
illustrating?
9. Which step of natural selection is the photo illustrating?
a. overproduction b. selection c. variation
d. adaptation
a. overproduction b. variation c. selection
d. adaptation
6. Which type of adaptation is a poision dart frog’s
poisonous skin?
19
10. Which type of adaptation is being shown by these snow
monkeys grooming each other?
A.
a. Structural b. Behavioral c. Structural
B.
11. Coconut trees can produce up to 50 cocnuts each season.
Which step of natural selection is the example
illustrating?
C.
14. When checking leg length for a species of lizard found,
scientists discovered a change in the distribution as
shown in graph B above. Based on this information, the
lizard population is undergoing _____.
a. stabilizing selection b. directional selection
c. artificial selection d. disruptive selection
a. overproduction b. variation c. selection
d. adaptation
12. Which type of adaptation is Emperor Penguin’s huddling
together? Is the adaptation from a biotic or an abiotic
selection factor?
15. Which of the graphs above demonstrates directional
selection?
a. A b. B c. C
16. Which of the graphs above demonstrates disruptional
selection?
a. A b. B c. C
17. Which of the graphs above demonstrates stabilizing
selection?
a. A b. B c. C
a. behavioral b. physiological c. structural
13. Which type of adaptation is this pant’s ability to store
water in its stem?
18. Which answer BEST shows an animal's structural
adaptation to the tropical rain forest?
a. baleen in filter feeding whales b. camouflage in a tree
frog c. migration of birds in winter d. the long neck of
a giraffe
19. The average individuals of a population are favored in
_____ selection.
a. stabilizing b. disruptive c. directional d. natural
20. _____ selection favors one extreme form of a trait in a
population.
a. stabilizing b. directional c. disruptive d. natural
a. Structural b. Behavioral c. Physiological
20
Matching
a.
b.
c.
d.
Darwin Statement
Lamarck Statement
Directional Selection
Disruptional Selection
e.
f.
g.
h.
21.
Type of selection where one extreme does not survive and the
other does.
22. Type of selection where the extreme individuals do not
survive.
23. Duck’s stretch the webbing between their toes so help
them swim faster.
Stabilizing Selection
Natural Selection
Sexual Selection
Artificial Selection
26. Type of selection where the average individuals do not
survive.
27. Type of selection that describes how more “fit”
individuals survive and reproduce.
28. Acts on an organism's ability to obtain or successfully
copulate with a mate.
24. Type of selection that chooses a trait chosen by humans.
25. “In the struggle for survival, the fittest win out at the
expense of their rivals because they succeed in adapting
themselves best to their environment."
Identify the four statements of natural selection from the sentences below, place the lettered sentence that provides the best
example for each statement.
a.
A snail like animal called a Limpet lives in tidal pools. Rory, a ten year old, notices that limpets come in
three colors. They are light gray color when found high on the rocks when the tide is out. He found a few
dark gray individuals, but most of the other limpets were a very dark brown. Especially when he looked in
the deeper tide pools with similar colored kelp and seaweed.
b.
Rory was interested in limpets after finding them and found out on Wikipedia that they start out as males and
change to female as they age. When it is time to spawn, males and females release millions of sperm and egg
in the hopes that some will survive.
c.
When Rory was in college studying zoology, he went back the pools and found that the dark gray limpets
had all but disappeared. He hypothesized that the light grey blended in with the dry rock and the dark brown
were hidden in the kelp.
d.
After finishing his doctorate on the limpet, Rory found that his childhood observations were correct. 25
years after his first visit to the tide pools, the dark gray limpet was almost completely missing from the
population of the Northern Oregon coast.
29. In any population, variations exist.
31. Organisms produce more organisms than can survive.
30. Overtime, offspring with “beneficial” variations will
make up most of the population.
32. Individuals with certain “useful” or beneficial variations
survive and pass on their variations to the next
generation.
21