This lab will examine the factors that influence population growth. You must complete the Lab 11 datasheet, attached below. Please read the instructions carefully before answering.
LAB
11
Modeling Population Growth
Bio 106 Life Sciences
Brightpoint Community College
OBJECTIVES
After this exercise, you should be able to:
· Distinguish between exponential and logistic growth.
· Identify carrying capacity.
· Distinguish between density-dependent and density-independent limiting factors.
· Apply models to real data sets.
· Make inferences about new data sets, such as human population on Earth.
A major area of ecological research is the study of how population size changes over time. A population is a group of individual organisms of the same species living in a particular area. Populations of all species have the potential to rapidly increase when resources are abundant, decrease when resources are not available, or minimally fluctuate. Mathematical models help scientists explore population dynamics by focusing on the factors that influence the growth or decline of populations. These mathematical models help scientists make better predictions about future changes in population size and growth rate. Predictions about changes in population size are useful for determining the resources needed for biodiversity conservation, predicting human population growth, or understanding impacts on population growth due to climate change or other environmental factors.
In the simplest mathematical model of population growth, exponential growth, as the population increases in size, more individuals reproduce, and the population begins to grow faster and faster. However, while the population size may grow rapidly, the rate of population growth stays the same. A simple example of exponential growth is the numerical growth sequence 2, 4, 8, 16, 32, 64, and so on, which doubles (increases 100%) at each interval. When the increase in quantity over time is plotted, this type of growth yields a curve shaped like the letter ‘J’ (Figure 1A). Populations of all species have the potential to grow exponentially when resources are abundant or when organisms colonize a new habitat.
While exponential growth may continue for a brief time, in nature there is always some factor that limits population growth. Limiting factors are variables that keep a population from reaching its maximum growth rate and may include anything that reduces birth rate or increases the death rate. Density-dependent limiting factors are dependent on the population size. For example, parasites and disease can spread more easily in a dense population. Density-independent factors affect growth rate independent of population density. Density-independent factors include natural disasters, droughts, and forest fires. Limiting factors determine the maximum size of a population or carrying capacity (K). Carrying capacity varies seasonally and over time with the availability of limiting resources.
Logistic growth occurs in the presence of limiting factors. In the logistic growth model, the number of offspring produced by each individual is reduced as the population size increases. The result is new individuals are added to the population most rapidly at an intermediate population size, but as the population nears carrying capacity the growth rate drastically decreases. When the increase in quantity over time is plotted, this type of growth yields a sigmoid or S-shaped curve (Figure 1B).
In this lab, you will learn about the factors that influence population growth. After the activities, you will be able to distinguish between exponential and logistic growth, find carrying capacity, distinguish between density-dependent and density-independent limiting factors, apply the population models to data sets, and figure out carrying capacity from population data. You will also apply your knowledge of population growth to the human population on Earth.
I. African Lions: Modeling Populations Online Activity
Introduction to the fragile population of Ngorongoro Crater Lions
The Ngorongoro Crater has long been considered one of the best places on earth to see lions. Lion numbers here have waxed and waned, from a high of around 125 in 1975, when Ngorongoro had one of the densest populations of lions in Africa, to around 55 in 2014. Four lion prides now rule over this natural amphitheater, feasting on the bounty of Ngorongoro’s self-contained world.
The story of these lions begins in 1962, when rain flooded the crater and surrounding areas. Water streamed down the slopes and the floor was impassable to human traffic for months at a time. The rains brought a plague of biting flies that tormented the lions by sucking their blood and weakening them. Soon the lions began to die off and just nine females and one male remained.
Where this to happen elsewhere, more lions would have come, drawn by the abundant prey and an absence of other lion competitors. But only seven males migrated into the crater over the three years that followed. For three decades from 1965, no other lions descended into the crater, kept at bay by either the steep fortress walls of the crater or by the fiercely territorial habits of the prides that grew from those who had survived the plague of flies.
Although lion numbers grew tenfold in the 10 years to 1975, the damage had already been done: the lions had passed through a genetic bottleneck, one that would haunt Ngorongoro’s inbred lions for generations to come. Genetic variation is an insurance policy against extinction. For species with normal genetic variation, a change in conditions – climate change, the emergence of new viral or bacteriological strains, the clearing of habitat – can be weathered because sufficient individuals should be able to draw on the necessary genetic variation for the species to survive. In the case of the Ngorongoro lions, the theory goes, if a single lion is affected, all Ngorongoro lions should be at risk similarly, because their genes are so similar. The low genetic variability should also give rise to lower fertility and to a high proportion of congenital birth defects.
This interactive simulation uses data from that isolated lion population in Ngorongoro Crater in Tanzania. As you go through the simulation, you will learn how to predict and model population growth.
Materials
· Computer
· Lab Data Sheet
Procedure:
1. Open the simulation, “ African Lions: Modeling Populations .”
2. Use the questions below to record your answers as you complete this assignment. Note: The question prompts correlate with the page numbers on the simulation so you can follow it easily.
3. Split your monitor into two windows. Place the simulation on one side and the lab answer sheet on the other side.
4. You will be required to take screenshots of graphs as prompted on the lab data sheet. If you do not know how, use Google or YouTube to find out how to use your device. Video tutorial of expectations.
5. To advance to the next page on the simulation, look for the “next” button in the lower right corner of the screen. The page numbers are listed in the bottom center of the screen.
6. Warning: This simulation will not allow you to go back to a previous page. If you need to go back, then you must restart the simulation.
To help you remember your answers for the post-lab quiz, use this answer sheet. If you turn it this copy in, you will receive a grade of zero on the file upload question. Use the lab data for the file upload question at the end of the post-lab quiz.
Post Lab 11 Data Sheet. Name: _______________
Answer the following questions as you go through the African Lions Modeling Activity. Note: The question prompts correlate with the page numbers on the simulation so you can follow it easily.
To submit this activity
· All of your answers to the multiple-choice questions should be transferred to the post-lab quiz.
· All of your answers for the Lab Data Questions should be transferred to the Lab Data Sheet. Save the lab data sheet as a PDF and upload to the last question on the post-lab quiz.
1. Page 1: Which of the following is an example of ecology?
b. looking for planets in outer space
c. creating pharmaceutical drugs
d. studying how global warming affects whales.
2. Page 2: Which of the following questions interests you the most? Highlight your answer in yellow.
a. What factors can influence how populations change over time?
b. What is the difference between exponential and logistic growth?
c. How can we apply population models to real-world data?
d. What inferences can we make about human population growth?
3. Page 3: From 1960 to 1963, the population of Lyons in the crater decreased. Which of the following is most likely to have been true from 1960 – 1963?
a. More lions are immigrating than emigrating.
b. More lions died every year than were born.
c. No lions have died.
d. Both a and b
4. Page 4: What would have been true on average from 1952 – 1956?
a. birth rate > death rate
b. death rate > birth rate
Continue to the next page
LAB DATA QUESTION 1.
|
Page 5: Take a screenshot of your graph with your prediction, delete the graph below, then paste your graph. If you are not sure how to do this, watch the tutorial: Video Tutorial. How to draw your prediction on the graph in the simulation: There are directions to the left of the graph about the middle of the text. Read them. I recommend positioning your mouse, click, move slightly, then click mouse again. Repeatedly clicking and moving allows you to properly shape the graph in small steps. What do you predict will happen to the lion population after 1963? Explain. |
LAB DATA QUESTION 2.
|
Page 6: Take a screenshot of your graph with your prediction, delete the graph below, then paste your graph. If you are not sure how to do this, watch the tutorial: Video Tutorial. There is no right or wrong answer for your prediction. |
Question 7. Page 7: What type of growth did the bacterial exhibit?
a. Exponential
b. Logistical
Question 8. Page 8: What hour was bacterial growth the fastest?
a. Hours 8 to 10
b. Hours 10 to 12
c. Hours 13 to 14
Question 9. Page 9: Look at the lion population from 1963 to 1975. Do you think this rate of growth will continue to increase? Go back and reread the introduction to Part I before answering this question.
a. The population will continue to increase because of migration of new lions into the crater.
b. The population will increase for a while then stop increasing because they will run out of food, space, or hit another limiting factor.
c. The population will decrease due to fly bites during the dry seasons.
Question 10. Page 10:
Using the picture in the simulation, brainstorm and choose 3 limiting factors that might affect the population in the crater.
· Space
· Food
· Snowstorms
· Territory
· Predators
Question 11. Page 11: Why does the rate of bacterial growth slow down?
a. The bacteria experience density-dependent limiting factors such as running food in the petri dish.
b. The bacteria experience density-independent limiting factors such as a natural disaster in the petri dish.
c. Neither A nor B. Bacterial populations can continue to grow unchecked in the petri dish.
Continue to the next page
LAB DATA QUESTION 12. Page 12:
|
Take a screenshot of your graph with your prediction, delete the graph below, then paste your graph. How to draw your prediction on the graph in the simulation: Position your mouse, click, move slightly, then click mouse again. Repeatedly clicking and moving allows you to properly shape the graph in small steps. |
LAB DATA QUESTION 13. Page 13
|
Take a screenshot of your graph with line showing the carrying capacity, delete the graph below, then paste your graph. How to Draw Carrying Capacity Line in the Simulation: Click once near the y-axis on the left side of the graph and an orange dot will appear. Click again on the right side of the graph and the line will be drawn. You can then move it up and down if you click on the dots to align it properly. Reference Figure 19.5 in Concepts of Biology Textbook for explanation on how to draw carrying capacity. Based on where you drew your line, what is your estimated carrying capacity? The carrying capacity is where your line intersects the y-axis? |
LAB DATA QUESTION 14. Page 14.
|
Take a screenshot of your graph with line showing the carrying capacity of the hypothesis, delete the graph below, then paste your graph. What was the environment’s carrying capacity before the disease outbreak? (Hint: Where does the line for carrying capacity intersect the y-axis in the middle of the graph) |
Continue to the next page
LAB DATA QUESTION 15. Page 15
|
Take a screenshot of your graph with your prediction, delete the graph below, then paste your graph. If you are not sure how to do this, watch the tutorial: Video Tutorial. Do not repeatedly click to draw your prediction: Position the mouse, click, then hold the button down and draw your prediction. LAB DATA QUESTION 16. Page 16 Compare your prediction to the real data. Is your prediction correct? If there are differences, suggest at least 2 causes. |
Question 17. Page 17: Which of the following in a density- independent limiting factor that could cause fluctuations in the carrying capacity between 1995 and today?
a. There is a drought for 2 years.
b. African wild dogs move into the crater and compete with alliance further wildebeest and zebra prey.
c. A disease wiped out most of the zebras.
d. Half the craters 3200 square miles is fenced off of the development of a game reserve.
Continue to the next page.
LAB DATA QUESTION 18. Page 18.
|
Review the graph on Page 18 and then do some research before answering the questions below. Cite three references or you will be given a zero for plagiarism. a. Given the shape of these graphs, do you think Earth’s population will reach carrying capacity? b. What might be some limiting factors? c. What do you think will happen if we do reach carrying capacity? References: 1. 2. 3. |
LAB DATA QUESTION 19. Page 19. Answer these questions and 1 or 2 sentences using what you have learned in the lab. It’s
a) What factors can influence how populations change over time?
b) What is the difference between exponential logistical growth?
c) How can we apply population models to real-world data?
d) What inferences can we make about the human population?
Continue to the next page
Activity II: Modeling Population Assessment.
Introduction:
When Yellowstone National Park was created in the late 1800s, wolves were on the decline.
· In the 1800s, the wolf population hovered between 100- 160 wolves in the park.
· The last wolves in Yellowstone were killed in 1926.
· In 1995, gray wolves were reintroduced to the park.
LAB DATA QUESTION 20. Using what you learned about population growth in Activity I, predict the growth of the wolves by drawing a growth curve on the graph. Hint: Read the introduction to the activity before you draw the graph.
· You may draw either an exponential or logistical growth curve on the graph.
· If you predict logistical growth, label the carrying capacity. Example of graph with carrying capacity (K) labeled.
|
|
Instructions on How to Draw the Graph
Choose one of the following methods:
· Open on a tablet and use a digital pen, delete the blank graph, and insert completed graph. Initialize and date graph
· Print this page, draw a line by hand, take a picture, delete the blank graph, and insert. Initialize and date graph.
· Copy the graph into a drawing program, draw the line, delete the blank graph, and insert. Initialize and date graph.
Question 21. How would you describe this type of growth?
a. Logistic
b. Exponential
Question 22. Choose the three density-dependent limiting factors that could slow population growth:
· Disease
· Natural Disasters
· Floods
· Competition
· Predation
Question 23. The maximum number of individuals an environment can support is the number at which population’s size stabilizes and levels out. This is called _____?
a. Extinction Value
b. Reintroduction Limit
c. Carrying Capacity
Question 24. In logistic growth, where is competition for resources highest?
a. Competition for resources is highest when the population level is well below carrying capacity.
b. Competition for resources is highest when the population level is at its lowest density level and there are plenty of resources per both. This would occur far away from carrying capacity.
c. Competition for resources is highest in the population level is at its highest density level and there are fewer resources per wolf. This would occur near carrying capacity
Question 25. Are there any wild populations that undergo endless population growth? Why/why not?
a. In nature, some populations can sustain endless population growth because they do not have limiting factors such as food, sunlight, water, or temperature.
b. In nature, all populations cannot sustain endless population growth because of limiting factors such as food, sunlight, water, temperature, or space.
Question 26. Are humans different from other wild populations? How are they different? Choose the 2 correct answers.
· Humans have limitations on population growth but wild animal populations do not.
· Humans cannot manipulate their environment, but wild animal populations can.
· Humans can manipulate their environment in ways that animals cannot.
· Humans do not have the limiting factors right now, but wild animal populations do.
How to Submit:
a. Transfer your answers to the multiple-choice questions to the post lab quiz.
b. Save lab data sheet as a PDF.
c. Upload the lab sheet to the last question with all screenshots. Students may not upload multiple files.
d. Submit the Post-Lab Quiz.
Part 2 is adapted from. https://concord.org/wp-content/uploads/2016/12/projects/smartgraphs/SG-African-Lions-Lesson-Plan.pdf (Accessed on 09/25/2020)
1
2
image1.png
image2.png
image3.png
image4.png
image5.png
image6.png
image7.png
image8.png
,
Post Lab 11 Data Sheet. Name: _______________
Answer the following questions as you go through the African Lions Modeling Activity. Note: The question prompts correlate with the page numbers on the simulation so you can follow it easily.
To submit this activity
· At the end of the lab protocol, there is a list of multiple-choice and lab data questions.
· Transfer the Lab Data questions to this Lab Data Sheet
· Transfer the answers from the multiple-choice/multiple answer questions to the post lab quiz.
· Save as a PDF and upload to the last question on Post-Lab 11 Quiz.
·
LAB DATA QUESTION 1.
|
Page 5: Take a screenshot of your graph with your prediction, delete the graph below, then paste your graph. If you are not sure how to do this, watch the tutorial: Video Tutorial. How to draw your prediction on the graph in the simulation: There are directions to the left of the graph about the middle of the text. Read them. I recommend positioning your mouse, click, move slightly, then click mouse again. Repeatedly clicking and moving allows you to properly shape the graph in small steps. What do you predict will happen to the lion population after 1963? Explain. |
LAB DATA QUESTION 2.
|
Page 6: Take a screenshot of your graph with your prediction, delete the graph below, then paste your graph. If you are not sure how to do this, watch the tutorial: Video Tutorial. There is no right or wrong answer for your prediction. |
LAB DATA QUESTION 12. Page 12:
|
Take a screenshot of your graph with your prediction, delete the graph below, then paste your graph. How to draw your prediction on the graph in the simulation: Position your mouse, click, move slightly, then click mouse again. Repeatedly clicking and moving allows you to properly shape the graph in small steps. |
LAB DATA QUESTION 13. Page 13
|
Take a screenshot of your graph with line showing the carrying capacity, delete the graph below, then paste your graph. How to Draw Carrying Capacity Line in the Simulation: Click once near the y-axis on the left side of the graph and an orange dot will appear. Click again on the right side of the graph and the line will be drawn. You can then move it up and down if you click on the dots to align it properly. Reference Figure 19.5 in Concepts of Biology Textbook for explanation on how to draw carrying capacity. Based on where you drew your line, what is your estimated carrying capacity? The carrying capacity is where your line intersects the y-axis? |
LAB DATA QUESTION 14. Page 14.
|
Take a screenshot of your graph with line showing the carrying capacity of the hypothesis, delete the graph below, then paste your graph. What was the environment’s carrying capacity before the disease outbreak? (Hint: Where does the line for carrying capacity intersect the y-axis in the middle of the graph) |
Continue to the next page
LAB DATA QUESTION 15. Page 15
|
Take a screenshot of your graph with your prediction, delete the graph below, then paste your graph. If you are not sure how to do this, watch the tutorial: Video Tutorial. Do not repeatedly click to draw your prediction: Position the mouse, click, then hold the button down and draw your prediction. LAB DATA QUESTION 16. Page 16 Compare your prediction to the real data. Is your prediction correct? If there are differences, suggest at least 2 causes. |
LAB DATA QUESTION 18. Page 18.
|
Review the graph on Page 18 and then do some research before answering the questions below. Cite three references or you will be given a zero for plagiarism. a. Given the shape of these graphs, do you think Earth’s population will reach carrying capacity? b. What might be some limiting factors? c. What do you think will happen if we do reach carrying capacity? References: 1. 2. 3. |
LAB DATA QUESTION 19. Page 19. Answer these questions and 1 or 2 sentences using what you have learned in the lab. It’s
a) What factors can influence how populations change over time?
b) What is the difference between exponential logistical growth?
c) How can we apply population models to real-world data?
d) What inferences can we make about the human population?
Activity II: Modeling Population Assessment.
Introduction:
When Yellowstone National Park was created in the late 1800s, wolves were on the decline.
· In the 1800s, the wolf population hovered between 100- 160 wolves in the park.
· The last wolves in Yellowstone were killed in 1926.
· In 1995, gray wolves were reintroduced to the park.
LAB DATA QUESTION 20. Using what you learned about population growth in Activity I, predict the growth of the wolves by drawing a growth curve on the graph. Hint: Read the introduction to the activity before you draw the graph.
· You may draw either an exponential or logistical growth curve on the graph.
· If you predict logistical growth, label the carrying capacity. Example of graph with carrying capacity (K) labeled.
|
|
Instructions on How to Draw the Graph
Choose one of the following methods:
· Open on a tablet and use a digital pen, delete the blank graph, and insert completed graph. Initialize and date graph.
· Print this page, draw a line by hand, take a picture, delete the blank graph, and insert. Initialize and date graph.
· Copy the graph into a drawing program, draw the line, delete the blank graph, and insert. Initialize and date graph.
How to Submit:
· Save as a PDF file.
· Upload to the last question on the Post Lab 11 Quiz.
1
2
image1.png
image2.png
image3.png
image4.png
image5.png
image6.png
image7.png
