Unit: Evolution

4th Six Weeks

Pre-AP Biology

Test and Quiz dates as follows:

Name:_________________________ Pd: _______

Pg. 1

Misconception: “Evolution is a theory about the origin of life”

Evolutionary theory deals mainly with how life changed after its origin. Science

does try to investigate how life started (e.g. whether or not it happened near a

deep sea vent, which organic molecules came first, etc…), but these

considerations are not the central focus of evolutionary theory. Regardless of how

it started, afterwards it branched and diversified, and most studies of evolution

are focused on these processes.

Pg. 2

Name: Date: Period:

“The day the Mesozoic

Died”

1. What interesting characteristic was found in the limestone of Italy?

2. Which scientist from the U.S. examined the dark layer of clay found in the sediment?

3. What was also found in the limestone rocks of Spain?

4. Describe the K.T. boundary. What does the K.T. boundary represent?

5. What caused the high levels of Iridium found in the clay?

6. How did they verify the Iridium levels were not due to a super nova?

7. How big of an asteroid or comet had to hit the earth to prove Alvarez’ theory?

8. Why did paleontologists hesitate to accept Louis Alvarez’ theory of the comet crash?

9. What new clues led scientists to the Brazos River in Texas?

10. What did Hildebrand find in the K.T. boundary which helped support the

theory of the comet crash?

11. After the Brazos River, scientists investigated which peninsula to find

evidence of the crater?

12. What was the name of the crater and how did they verify it was the crater Louis Alvarez had predicted?

13. What did scientists examine to determine the history and evolution of life in South Dakota?

Pg. 3

14. What can you infer about animals found in the same layer of rock? Which species are considered

“younger” in the fossil record; those found above or below the K.T. boundary? Why?

15. Currently, have there been any dinosaur fossils found above the KT Boundary?

16. After the asteroid hit, what factors caused the death of the dinosaurs and the end of the Mesozoic era?

17. Describe what happened to plant life after the asteroid?

18. Which plant species arose soon after the end of the Mesozoic period?

19. Which organisms survived the comet impact?

20. According to theorists, could humans have evolved without the comet crash and the end of the

Mesozoic period?

Pg. 4

How Fossils Are Made The Kinds of Fossils Paleontologists are people who study ancient life. Because they study

life forms that are now extinct, they rely on fossils to learn about life in

the past. Fossils are the remains of living things that have transformed

into stone over millions of years.

Most fossils are found in sedimentary rock. The fossils are made when

living things die and get buried by sediments quickly before the hardest

parts of the animal have a chance to decay. As sediments accumulate,

pressure causes the sediments to harden into rock: Sand sediments

become sandstone, clay sediments become shale, and shell sediments

become limestone.

Groundwater carrying minerals seeps into the sedimentary rock and

helps the fossils form in one of two ways. Sometimes the minerals fill in

all of the empty places of the once living thing and form crystals. These

crystals cause the remains of the living thing to harden along with the

sedimentary rock that it is encased in. Petrified wood is an example of

this process, which is called permineralization.

At other times, the minerals in the groundwater actually replace the

minerals that make up the remains. So over time the hard parts are

completely replaced by other minerals. This process is called

replacement.

Other important fossils are impressions and molds. These are made

when a hard part such as a shell, fills up with sediments that harden,

and then the actual shell dissolves leaving nothing but the sediment

mold. These molds can tell us much about the body structures of

animals and plants.

As well, insects also get trapped in amber, which is fossilized tree sap.

In the movie Jurassic Park, scientists used dinosaur DNA from the

stomachs of mosquitoes trapped in amber to genetically engineer

dinosaurs.

Some animals have even been trapped in ice, too, preserving them

extremely well. Woolly mammoths and mastodons have been found

with hair intact and bones in good condition. Likewise, some animals

and plants have been mummified in hot arid conditions like those

found in deserts.

Finally, paleontologists can learn about ancient life from trace fossils.

Trace fossils are things like footprints or animal droppings, which can

tell us about the animal’s behavior.

Living things (usually aquatic) die and then get

buried quickly under sand, dirt, clay, or ash

sediments. Usually, the soft parts decay, or rot

away, leaving the hard parts behind. These are

ammonites, one of the most common fossils that

are found.

As time goes on more and more sediment accumulates. Pressure, heat, and chemical reaction cause the sediments to harden into rock called sedimentary rock.

Movements in the earth’s crust, pushes the layers

of sedimentary rock back up to higher ground.

Finally, through erosion caused by

weather, wind, and water, the

fossils become exposed at the

surface again.

Layers of rock are referred to as strata. Using the strata

In the rock diagram on the right, predict the:

1. Oldest layer of rock = _____________________

2. Youngest layer of rock = ___________________

The table below is a cross-section of layers of sedimentary rock that were

found to contain fossils of closely related species based upon their

anatomical similarities. Use the table below to answer questions 3 and 4.

3. Which species are of the youngest fossil species found? __________________________________

4. Which species are most closely related to species A? _________________

Use the diagram on the right to answer questions 5-9.

5. Which layers are the same? ____ and ____; ____ and ____

6. Of the rock layers E and F, which is the oldest? ____

7. What is the correct sequence of rock layer from oldest to

youngest? ____, ____, ____, ____, ____, ____

8. An unconformity (buried erosional surface) is represented

by the interface between which two layers? ____ and ____

9. The diagrams below show layers of rock located in two different geographic locations, several miles

apart. Both cliffs are composed of undisturbed layers of sedimentary rock. Which layer would contain

the oldest fossils? ____________

1.

2.

3.

4.

5.

Layer Identification (Top To Bottom)

Fossil Species Found

Top Layer C and D

2nd Layer C only

3rd Layer A, B and C

4th Layer A and B

Bottom Layer A only

Sun

Surface of the Earth

Rock Diagram

A

B

C

D

E

Earth’s Core

F

G

H

I

J

Pg. 6

EVOLUTION NOTES

I. Evolution – accounts for the diversity of life on Earth

Evolution =

process by which modern organisms have descended from ancient organisms

II. Theories of Evolution

A. Scientific theory –

ex:

NOT a guess or hunch

B. Jean-Baptiste Lamarck – theory of evolution – 1809

Lamarck’s theory: by selective use or disuse of organs, organisms acquired or lost traits during their lifetime; these traits could then be passed on to their offspring

ex:

Problem:

C. Charles Darwin – contributed more to our understanding of evolution than anyone

III. Ideas that shaped Darwin’s thought on evolution

A. Made observations, collected evidence –

observed similar species well suited to the environment they inhabited

traits of similar species varied noticeably among different islands of the Galapagos

o ex:

hypothesized that animals adapted to local conditions on islands after their arrival

B. James Hutton and Charles Lyell – studied geology in early 1800’s

C. Thomas Malthus and human population growth – 1798

- if the human population continued to grow unchecked –

D. Farmers and artificial selection

- nature provides the variation –

ex: cows and milk production, hogs and muscle, horses and speed

Pg. 7

IV. Evolution by natural selection proposed by Darwin in On the Origin of Species, 1859

A. – more offspring are produced than can survive; members of each species compete to obtain food, living space, and other necessities of life

B. = Natural Selection a. individuals with an adaptation that makes them more “ fit” for a certain environment will

survive and reproduce at a higher rate b. - inherited characteristic (trait) that increases an organism’s chance of

survival ex:

c. - ability of an individual to survive and reproduce in its specific environment

C. – each living species has descended, with changes, from common ancestor

V. Evidence of evolution

A. – examples of many species that have lived for a time and then became extinct

B. – looking at similar environments on different continents,

animals have similar anatomy and behavior because of adaptation ex: beaver (N. America) and capybara (S. America)

i. muskrat (N. America) and coypu (S. America)

C. (similar or corresponding) body structures – structures that have different mature

forms but develop from the same embryonic tissues; a. strong evidence that

D. – organs so reduced in size that they are just

vestiges (traces) of homologous organs in other species ex:

E. – early stages (embryos) of many vertebrate animals are very similar

F. components of and amino acids sequences show evolutionary relationships.

a. bases ( ) b. Converting to for .

Pg. 8

VI. Evolution of Populations (Chapter 16 – p. 392-410)

A. – a group of individuals of the same species that interbreed

– all the genes of all the members of a particular population (all alleles)

(in genetic terms) - any change in the relative frequency of alleles in a population

B. Sources of genetic variation within a population

1. Mutations – change in the sequence of DNA;

2. – genes combining in new ways during production of gametes and crossing over (meiosis)

3. Gene Flow – transfer of genes between populations ex: VII. Evolution as genetic change

A. Evolution by Natural selection: -acts on

-never acts directly on genes entire organisms survive to reproduce, or die and do not reproduce.

Single-gene and Polygenic Traits

1. : natural selection on single gene traits can lead to changes in allele frequencies and thus to evolution. ex: polydactyl (6 fingers) versus normal digit number (5 fingers)

2. : effects on allele frequencies

much more complex a) – individuals at one end

of curve have higher fitness

ex. anteaters with long tongues better for capturing ants

b) – individuals near center of curve have higher fitness

ex. Human baby weight at birth – too small low survival, but too large difficult birth

c) – upper and lower ends of curve have higher fitness

ex. large and small seeds common – birds beaks are large or small

B. Gradualism and Punctuated Equilibrium 1. : change that occurs in a species at a slow steady pace 2. : rapid sudden change in a species

ex: light brown and black pocket mice after volcanic eruption in New Mexico

Pg. 9

C. Evolution by Genetic Drift –

Certain individuals may leave more descendants than others, and over time this can cause an allele to become common in the population. Caused by chance, not natural selection.

VIII. Speciation–

– group of organisms that breed with each other and and produce fertile offspring in the natural environment

A. How do new species arise? 1. = when members of two populations cannot

interbreed and produce fertile offspring.

2. How does reproductive isolation occur? -behavioral isolation –

ex: Eastern meadow lark will not respond to Western meadowlark mating songs

-geographic isolation – population separated by ex: one population of squirrels divided into 2 or more smaller populations by formation of Grand Canyon

-temporal isolation – populations reproduce at ex: plant species that flower at different times of the year; toad species that live in same area, but one species mates in early summer and other in late summer

3. Darwin’s finches –

- descended from a common ancestor from mainland S. America

- natural selection shaped beaks as they adapted to different foods on different islands B. Divergent Evolution –

ex: red fox and kit fox

--red fox lives in forest where red color blends with trees; kit fox lives in deserts where its light brown color blends in with sandy environment

--similarity in structure indicates a common ancestor, but as they adapted to different environments the appearance of 2 species diverged

C. Convergent Evolution –

ex: cactus growing in American desert resembles cactus which grows in African desert. Both have fleshy stems for storing water and spines to ward off predators.

Pg. 10

EVERYDAY EVOLUTION: Antibiotic Resistant Bacteria

Evolution is a process which requires genetic varieties, large population changes, and long periods of time. Thus, it is very challenging to see evolution occur in one lifetime. Can you think of a modern day example of evolution you’ve encountered? Certain species of bacteria are common examples of potentially life threatening evolution. Recall that bacteria are tiny, unicellular, prokaryotic organisms. Bacterial reproduction occurs through a

quick and simple form of asexual mitosis. This form of reproduction can occur at alarming speeds and has

given bacteria the ability to evolve in short periods of time!

View the diagram below. Harmful (disease causing) bacteria can be treated using antibiotic drugs, which

destroy bacteria if taken correctly. However, some bacteria have resistance to antibiotics due to random

genetic mutations. This small population of bacteria, if left untreated, could reproduce and create a new

antibiotic resistant strain.

Using the above information and previous knowledge, let’s analyze the following questions and scenarios:

1. Are bacteria living or non-living? Do they contain genetic material?

2. What causes new species of bacteria to arise in a population?

3. Doctors inform patients to take all of their antibiotics even if symptoms subside. What are doctors

attempting to reduce or avoid?

4. In recent years, agricultural industries have started injecting their livestock with antibiotics to

increase muscle tissue growth. What concerns could be raised to the agricultural industry about

the overuse of antibiotics?

Pg. 11

Phylogeny

Darwin’s ideas about descent with modification have given rise to the study

of____________, or evolutionary _____________ among organisms.

Understanding a phylogeny is a lot like reading a family tree. The ______ of the tree

represents the _______________, and the tips of the _________ represent the

____________ of that ancestor. As you move from the root to the tips, you are moving

___________________.

When a lineage splits (___________), it is represented as ____________ on a

phylogeny. When a speciation event occurs, a single ancestral lineage gives rise to two or

more daughter lineages.

Speciation—to form a ______________________ from an existing one.

Pg. 12

Misconceptions about Humans:

The phylogeny of living species most closely related to us looks

like this:

It is important to remember that:

Humans ______________ from chimpanzees. Humans and chimpanzees are possibly

evolutionary _________ and might share a recent _______________ that was neither

chimpanzee nor human.

Pg. 13

Vocabulary Etch-a-Sketch:

Natural Selection

Natural selection is also known as survival of the fittest. Any population of organisms

has variation in traits: all humans have some differences; all oak trees have some differences,

as do all alligators, all beetles, and so on. Some organisms will be better suited or a better fit

to their environment and will survive and reproduce more successfully. Let’s consider a

population of beetles:

1) Some are striped and some are a solid brown, so there is variation in the trait of

color.

2) Striped beetles get eaten by birds because they stand out against the tree bark, so

more solid brown beetles survive and reproduce - not everyone gets to

reproduce equally.

3) Solid brown beetle parents have solid brown beetle babies because the trait is

controlled by genes – the trait is hereditary.

The end result: the more advantageous trait, solid brown color, becomes more common in the

beetle population. Their phenotype allows them to be more fit and they pass these genes on

to the next generation. The population evolves by natural selection on the beetle phenotype

of pattern and color.

Adaptations

An organism is more fit to an environment because of its adaptations. An adaptation is

any inherited characteristic or trait that increases the chance of survival. For example, animals

that are white in the Arctic are better adapted to their environment. A white rabbit can hide

better from predators, and a white polar bear can be more successful at hunting seals because

of their coloration. Because of this adaptation, they will survive better and reproduce more,

getting more of their genes into the next generation of Arctic rabbits and polar bears.

Random mutations are the origin of these adaptations.

Pg. 14

Directions: On a separate sheet of paper - sketch and color an example of natural selection.

1. Choose:

a. Organism – plant, animal, insect, etc…

b. 1 Trait/adaptation – two or more variations

Ex: blonde hair, brown hair, red hair

c. Environment or biome – habitat of organism

Ex: arctic tundra, grassland, desert

2. In a short paragraph, describe which trait variation is advantageous for the organism’s

survival and explain how this variation will affect the organism’s population. How will

the species evolve over time?

3. Use the following vocabulary in your description:

a. Trait/adaptation

b. Survive or survival

c. Reproduce or reproduction

d. More fit or well suited

e. Population

f. Evolve or evolution

**PLEASE UNDERLINE OR HIGHLIGHT THE VOCABULARY ABOVE, WRITE DESCRIPTION

ON FRONT SIDE OF DRAWING**

4. Extension questions: Answer the following three questions on the back of your

drawing.

a. Where do different traits (i.e. long neck, short neck, etc…) come from?

b. Is a wide variety of genetic variation in a species an advantage or disadvantage for

an organism? Explain.

c. Are all mutations and traits beneficial? Can you think of a scenario where a trait

previously favored will no longer be beneficial to a species?

Pg. 15

Peppered Moth Investigation

Objectives:

Describe the importance of coloration in avoiding predation.

Relate environmental change to changes in organisms within an ecosystem.

Explain how natural selection causes populations to change.

Materials: sheet of white paper, white paper disks (60), sheet of newspaper, newspaper disks (60), forceps, watch or clock with second hand, pencils with different colors of lead (2)

Purpose: In this lab, you will simulate how successfully predators locate prey in different environments. Then you will analyze actual data and relate changes in a population of peppered moths with two color variations to changes in the environment.

Background:

Natural selection, the reproductive success of organisms best suited to their environment, is a driving force in evolution. Natural selection occurs within groups of individuals of the same species (populations). Genetic variations are the different types of genes for inherited traits, and is one factor in the reproductive success of certain members of a population. The result of natural selection is evolution or the changing of a population so that it is better suited to its environment.

Industrial melanism is the term used to describe the evolution of a population by the darkening of its populations in response to industrial pollution. One example of rapid industrial melanism occurred in populations of peppered moths in the area of Manchester, England from 1845 to 1890. Before the Industrial Revolution, the trunks of trees in the forest around Manchester were light grayish green due to the presence of lichens growing on the trunks. Most of the peppered moths in the area were light-colored with dark spots. As the Industrial Revolution progressed, the tree trunks became covered with soot and turned dark. Over a period of 45 years, a dark variety of the peppered moth became more common around Manchester.

Procedure: 1. Work with a partner and decide which of you will be the “predator” and which will be the timekeeper.

2. Place a sheet of white paper on your lab table. If you are the timekeeper, scatter 30 white paper disks and 30 newspaper disks on the paper while your partner looks away. The disks represent a bird’s prey. If you are the predator, use forceps to pick up as many disks as possible in 15 seconds while your lab partner watches the time. The forceps simulate a bird’s beak.

3. Count the number of each type of disk picked up in 15 seconds. Records these numbers in the data table on your answer sheet.

4. Replace the white paper with a sheet of newspaper. If you are the timekeeper, scatter 30 white paper disks and 30 newspaper disks on the newspaper. If you are the predator, repeat the hunting procedure while your partner watches the time. Again, record the numbers in the data table on your answer sheet.

5. Change roles with your partner and repeat steps 2-4.

Pg. 16

Name ______________________________ Date ___________________ Pd _____

Peppered Moth Investigation

Data Table

Total # of disks

scattered Total # of disks picked up

% of available prey recovered

Trial Background Newspaper White Contrasting Background

Matching Background

Contrasting Background

Matching Background

1 White 30 30

2 Newspaper 30 30

3 White 30 30

4 Newspaper 30 30

Analyzing Predator-Prey Relationships:

Examine the table at right which represents data from a 10-year study of a population of peppered moths. The numbers represent moths captured in traps that were located in the same area each year. 1. Using the grid below and the data table at right, construct

a graph comparing the number of each color of peppered moths captured. Plot the years of the study on the x-axis (horizontal) and the number of moths captured on the y-axis (vertical). Use a different color of pencil or some other means to differentiate the color variations of the moths. Be sure to label each axis and to make a key for the graph.

Year Number of light moths captured

Number of dark moths captured

2 537 112

3 484 198

4 392 210

5 246 281

6 225 357

7 193 412

8 147 503

9 84 594

10 56 638

Pg. 17

2. Using the graph you made in question 1, describe what happened in the population of peppered moths

in the sampled area. ___________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

3. How might the gene for dark coloration in the peppered moth have originated? __________________________

___________________________________________________________________________________________

4. Is coloration an important factor in successful predation? _____ Why? __________________________

____________________________________________________________________________________

____________________________________________________________________________________

5. What is the relationship between the environment and the peppered moths’ chances of survival?

____________________________________________________________________________________

____________________________________________________________________________________

6. Explain why an increase in the number of dark-colored peppered moths occurred during the Industrial

Revolution. __________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

7. What effect do you think using cleaner-burning fuels would have had on the environment and the

peppered moths near Manchester, England? _______________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

8. Summarize how this example of peppered moths in Manchester, England relates to Darwin’s theory of

natural selection. _____________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

____________________________________________________________________________________

Pg. 18

Name: Date: Period:

Making of the Fittest: Natural Selection and Adaptation

1. Describe the valley of fire.

2. What determined the dominant coat color in mice?

3. How did a new coat color arise?

4. What is a mutation?

5. Does evolution occur quickly? How long did it take for the pocket mice population to

evolve?

6. Define natural selection. Is this process random?

7. How did scientists prove natural selection to be a specific change?

8. If a volcanic eruption were to occur again and cover all sandy parts of the valley of fire

how might the pocket mice population change?

Pg. 19

Pg. 20

Name: Date: Pd:

Evolution Station Lab

Station 1: Fossils

1. Do you think the pattern of change shown by the horse teeth supports this hypothesis?

Why or why not?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

2. How would you test this hypothesis?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Station 2: Biogeography

1. Do you think the information given and map data support Allison’s hypothesis? Why or

why not?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

2. How would you test this hypothesis?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Pg. 21

Station 3: Molecular Homologies

1. Which organisms did you choose to analyze?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

2. Based on you analysis, hypothesize which two organisms are more closely related. How

do you know?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

3. How would you further test your hypothesis?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Number of amino acid

differences

Organism A vs. Organism B

Organism A vs. Organism C

Pg. 22

Station 4: Anatomical Homologies

1. Do you think the illustrations support this hypothesis? Why or why not?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

2. How would you test this hypothesis?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Station 5: Developmental Homologies

1. Why do you think that scientists hypothesize that Hox genes are homologous for all

animals?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

2. How would you test this hypothesis?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

Pg. 23

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Pg. 28

Name: Date: Pd:

Amino Acid Sequences & Evolutionary Relationships

Answer Sheet

Follow the procedures listed on the previous page

Part A: Comparing Hemoglobin

Pg. 29

Part B: Comparing Cytochrome C

Graph 1

Graph 2

Pg. 30

Pg. 31

Pg. 32

Chocolate Mimicry Mimicry is the ability to appear to be or to imitate something other than what you really are. The use of

mimicry is prevalent throughout nature and is a prime example of evolution by natural selection. Butterflies use it as a

protection mechanism in their larva stage and in the final adult stage. Either to trick predators into thinking they are an

inedible species or perhaps an entirely different organism all together. Foremost, the intention of mimicry is to draw

attention to yourself. This is usually achieved, but not always, by advertising your presence with bright colors. These

bright colors are probably easier for predators to learn and therefore likely reduces the number of casualties necessary

before the predator learns the pattern to avoid and providing the mimic with protection.

Brightly colored caterpillars and butterflies are essentially warning predators of impending unpalitability or

other physical dangers. This is achieved in several different ways. Some caterpillars and butterflies are poisonous and

others are not? Poisonous caterpillars have ability to ingest the toxins of their host plants as in the classic example of the

Monarch and the cardiac glycosides of the milkweed. These poisons are absorbed and retained during the larval stage

and passed on, through the transitional stage of metamorphosis, to the adult butterfly. Still others are protected by

irritating hairs of caterpillars such as the Mourning Cloak or by the foul odors from caterpillars like the Eastern

Swallowtail.

In the final adult stage we can find mimicry. One of the most striking examples is that of the Viceroy imitating

the Monarch. Since Monarchs are distasteful and will cause vomiting if consumed by a predator the lesson of avoiding

Monarchs is quickly learned. Viceroys finds protection through resemblance. A very important facet to this approach

and the key to its success is that the numbers of the imposters should not be too high in relationship the one being

imitated. The reasoning here is that if the ratio was as high as or approaching say, 50/50, it would be possible for the

predator to eventually learn the deception through trial and error and soon be able to recognize the perpetrator. In

order for this method to be successful the ratio needs to remain low.

Pg. 33

Pg. 34

Name: ______________________________________ Date: ________________________ Pd: ______

Student Exploration: Rabbit Population by Season

explorelearning.com

Vocabulary: carrying capacity, density-dependent limiting factor, density-independent limiting factor, limiting

factor, population, population density

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

1. Suppose you had a pet rabbit. What would the rabbit need to stay alive and healthy? _________________________________________________________________________

_________________________________________________________________________

2. A female rabbit can give birth to over 40 baby rabbits a year. Suppose all of her offspring survived and reproduced, all of their offspring survived and reproduced, and so on. If that happened, in only eight years the mass of rabbits would exceed the mass of Earth! So, why aren’t we overrun with rabbits? What keeps the rabbit population in check?

_________________________________________________________________________

_________________________________________________________________________

_________________________________________________________________________

Gizmo Warm-up

A population is a group of individuals of the same species that live in

the same area. The size of a population is determined by many factors.

In the Rabbit Population by Season Gizmo™, you will see how different

factors influence how a rabbit population grows and changes.

1. Select the BAR CHART tab. What is the approximate size of the

initial rabbit population? ______________

2. Select the TABLE tab. Click Play ( ), and allow the simulation to run for one year.

A. In which season did the rabbit population increase the most? __________________

B. In which season did the rabbit population increase the least? __________________

Pg. 35

Activity A:

Carrying capacity

Get the Gizmo ready:

Click Reset ( ).

Question: What determines how large a population can grow?

1. Think about it: A limiting factor is any factor that controls the growth of a population. What do you think

are some of the limiting factors for the rabbit population? ____________________________

_________________________________________________________________________

_________________________________________________________________________

2. Run Gizmo: Select the DESCRIPTION tab. Set the Simulation speed to Fast. Select the GRAPH tab. Click Play, and allow the simulation to run for at least 10 years. (Note: You can use the zoom controls on the right to see the whole graph.)

A. Describe how the rabbit population changed over the course of 10 years. ___________________________________________________________________

___________________________________________________________________

B. What pattern did you see repeated every year? _____________________________

___________________________________________________________________

___________________________________________________________________

C. How could you explain this pattern? ______________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

3. Analyze: The carrying capacity is the maximum number of individuals of a particular species that an environment can support. All environments have carrying capacities.

A. What is this environment’s approximate carrying capacity for rabbits? (Note: Average the summer

and winter carrying capacities.) ________________________________

B. When did the rabbit population reach carrying capacity? Explain how you know. ___________________________________________________________________

___________________________________________________________________

Pg. 36

Activity B: Density-dependent

limiting factors

Get the Gizmo ready:

Click Reset.

On the SIMULATION pane, make sure Ample is selected for the amount of LAND available.

Introduction: Population density is the number of individuals in a population per unit of area. Some limiting

factors only affect a population when its density reaches a certain level. These limiting factors are known as

density-dependent limiting factors.

Question: How does a density-dependent limiting factor affect carrying capacity?

1. Think about it: What do you think some density-dependent limiting factors might be?

_________________________________________________________________________

_________________________________________________________________________

2. Predict: Suppose a shopping mall is built near a rabbit warren, leaving less land available for rabbits. How will this affect the environment’s carrying capacity?

_________________________________________________________________________

3. Experiment: Use the Gizmo to find the carrying capacity with Ample, Moderate, and Little land. List the carrying capacities below.

Ample: _________________ Moderate: _________________ Little: _________________

4. Analyze: How did the amount of space available to the rabbits affect how many individuals the environment

could support? ______________________________________________________________

_________________________________________________________________________

5. Infer: Why do you think limiting a population’s space decreases the carrying capacity? _________________________________________________________________________

_________________________________________________________________________

6. Challenge yourself: Other than space, what might be another density-dependent limiting factor? Explain.

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Activity C:

Density-independent

limiting factors

Get the Gizmo ready:

Click Reset.

On the SIMULATION pane, select Ample for the amount of LAND available.

Introduction: Not all limiting factors are related to a population’s density. Density-independent limiting

factors affect a population regardless of its size and density.

Question: How do density-independent limiting factors affect how a population grows?

1. Think about it: What do you think some density-independent limiting factors might be?

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2. Gather data: Click Play. Allow the population to reach carrying capacity. Click Pause ( ). Select the

GRAPH tab and click the camera ( ) to take a snapshot of the graph. Paste the snapshot into a blank document. Label the graph “Normal Weather.”

3. Predict: How do you think a period of harsh winters will affect the rabbit population? _________________________________________________________________________

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4. Investigate: Click Reset. Select Harsh winter from the CONDITIONS listed on the SIMULATION pane. Click Play, and observe the how the population changes over five years. Paste a snapshot of the graph in your document. Label the graph “Harsh Winter.”

A. How does the Harsh Winter graph differ from the Normal Weather graph? ________ ___________________________________________________________________

B. What do you think most likely caused the differences seen in the two graphs? ___________________________________________________________________

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5. Predict: Rabbits reproduce in the spring. How do you think a period of cold springs will affect the rabbit

population? _______________________________________________________________

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(Activity C continued on next page)

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Activity C (continued from previous page)

6. Investigate: Deselect Harsh winter. Select Cold spring. Click Play, and observe the how the population changes over a period of five years. Paste a snapshot of the graph in your document and label the graph “Cold Spring.”

A. How does the Cold Spring graph differ from the Normal Weather graph? _________ ___________________________________________________________________

B. What do you think most likely caused the differences seen in the two graphs? ___________________________________________________________________

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7. Predict: How do you think a period of hot summers will affect the rabbit population? _________________________________________________________________________

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8. Investigate: Deselect Cold spring. Select Hot summer. Click Play, and observe the how the population changes over a period of five years. Paste a snapshot of the graph in your document. Label the graph “Hot Summer.”

A. How does the Hot Summer graph differ from the Normal Weather graph? ________ ___________________________________________________________________

B. What do you think most likely caused the differences seen in the two graphs? ___________________________________________________________________

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9. Think and discuss: Other than unusual weather, what might be another density-independent limiting factor that could affect the rabbit population? If possible, discuss your answer with your classmates and teacher. _________________________________________________________________________

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Practice Mechanisms of Evolution

Name Date Class

Write the term or phrase that best completes each statement. Use these choices:

genetic drift punctuated equilibrium directional selection disruptive selection

adaptation divergent evolution gradualism reproductive isolation

stabilizing selection convergent evolution camouflage

1. two or more related species becoming more and more dissimilar.

2. removes individuals with average trait values, creating two

populations with extreme traits.

3. The most common form of selection, , removes organisms with

extreme expressions of a trait.

4. is evolution by random chance not natural selection.

5. In , unrelated species become more and more similar in appearance as they

adapt to the same kind of environment.

6. will shift populations toward a beneficial but extreme trait value.

7. suggests populations remain genetically stable for long periods of time and

then are interrupted by periods of brief, rapid genetic change.

8. An is a feature that is common in a population because it provides some

improved function. It is well fitted to its function and is produced by natural selection.

9. The idea that evolution occurred in small steps over millions of years in a speciation model is currently

known as .

Refer to the figure. Respond to each statement.

10. Specify which moth is better fit for its environment.

11. State the name of the phenomenon illustrated.

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WORD BANK

A. Behavioral

Isolation

B. Mutation

C. Convergent

Evolution

D. Genetic Drift

E. Divergent

Evolution

F. Directional

Selection

G. Geographical

Isolation

H. Stabilizing

Selection

I. Punctuated

Equilibrium

J. Mimicry

K. Gradualism

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