Chat with us, powered by LiveChat Population Ecology Activity Worksheet Assignment | Abc Paper
+1(978)310-4246 credencewriters@gmail.com
Select Page

1. Discussion question:Globally, the human population is increasing exponentially. What are some of the reasons for this population explosion? Is it something that should be controlled? And if so, how might reproduction be curbed? 250 words2. Homework worksheet Assignment Instruction:In this unit, you learned that the characteristics of a population at a given time can be represented graphically using birth and death rate data, among many other parameters. In Part I of this activity, you will work with a simple data set to create a human survivorship curve and answer questions about the results and the data itself. In Part II, you will work with interactive age structure diagrams in an online simulator to analyze population growth trends for both China and the United States. For an example of an age structure diagram, see the presentations for the Unit II Lesson. Work Sheet is attached
unit_ii_assignment_student__1___1_.docx

unitii_lessonpresentation_part2__1_.pdf

unitii_lessonpresentation_part1__2_.pdf

Unformatted Attachment Preview

Name:
Population Ecology Activity
Introduction
In Unit II, you learned that the characteristics of a population at a given time can be represented graphically using birth and death rate data, among many other parameters. In Part I of this activity, you will
work with a simple data set to create a human survivorship curve and answer questions about the results
and the data itself. In Part II, you will work with interactive age structure diagrams (see unit lesson part II,
Slide 21, Figure 3 for an example) in an online simulator to analyze population growth trends for both
China and the United States.
Part I: Constructing a Survivorship Curve
Survivorship curves are created by estimating the age of an organism at the time of its death and the
number of deaths within each age bracket inside of a given population of organisms. Once constructed,
survivorship curves create a general picture of the life history of that organism. The two biggest influences
on the shape of a survivorship curve are predation and disease. There are three general survivorship
curve types:
Type III: Indicates a high mortality rate of the young.
Type II: Indicates a constant mortality rate throughout the life span of the organism.
Type I: Reflects a low mortality rate among the young with individuals dying at the end of their life span.
Activity
In the United States, the current average life span of a human female is about 83 years of age, and the
average life span of a human male is about 77 years. For this activity, we will assume that the average
life span is 80 years of age. For Table 2a below, age brackets in five-year increments were created. Age
data was collected randomly from 100 newspaper obituaries from around the United States and entered
into the age bracket Table 2a. Using this data, you will complete the survivorship information in Table 2b
and construct a survivorship curve using an Excel spreadsheet table. You will create a graph from the
data and import it later in this assignment.
Completing the Survivorship Data Table Procedure (Table 2b) (10 points)
1. Enter the data from “Number of Deaths” column for each age bracket in Table 2a into the “Number of
Deaths” column in Table 2b.
2. To calculate the data for the “Number of Survivors” column in Table 2b, start by subtracting the number
of deaths in age bracket 1-5 from the number of survivors in age bracket 0. This number will be 100, of
course. Continue subtracting the number of deaths in each age bracket from the number of survivors in
the preceding age bracket. (Hint: The number of survivors will be 100 until you get to age bracket 21-25,
where you will subtract 2, making the number for that bracket 98. Continue the process through the last
age bracket. The number of survivors in age bracket 91-100 should be 0).
3. Create a line graph using Microsoft Excel and the data from Table 2b. The X-axis should reflect the
Percent Life Span (%) and the Y-axis data should reflect the number of survivors data that you calculated.
Table 2a
Age Bracket
Number of Deaths
0
0
1-5
0
6-10
0
11-15
0
16-20
0
21-25
2
26-30
0
31-35
6
36-40
4
41-45
0
46-50
2
51-55
2
56-60
8
61-65
2
66-70
8
71-75
10
76-80
16
81-85
8
86-90
22
91-100
10
Total
100
Table 2b
Age Bracket (Age
of Death)
0
Percent of Life
Span (%)
Number of Deaths
(from Table 2a)
0
0
1-5
3.1
0
6-10
9.4
0
11-15
16
0
16-20
22
0
21-25
28
2
26-30
34
31-35
41
36-40
47
41-45
53
46-50
59
51-55
66
56-60
72
61-65
78
66-70
84
71-75
91
76-80
97
81-85
100
86-90
100
91-100
100
Number of Survivors
100
Complete The Graph (12 points)
Right click on the graph below, choose either edit data or edit data→edit data in Excel, and complete using the Number of Survivors data from table 2b. The graph will update automatically as data is entered.
Simply close the data entry window once complete.
Number of Survivors
1.2
Number of Survivors
1
0.8
0.6
0.4
0.2
0
0
3.1 9.4 16 22 28 34 41 47 53 59 66 72 78 84 91 97 100 100 100
% of Life Span
(Questions: 6pts each)
1. What type of survivorship curve do modern humans possess?
Resize as needed.
2. Would you expect that there is a difference in the survivorship of men and women? Explain why, or
why not?
Resize as needed.
3. Why do humans exhibit this type of survivorship curve? What factors are involved?
Resize as needed.
4. Why might obituaries be a poor source of data for determining a human survivorship curve?
Resize as needed.
5. The data for this exercise was collected from the United States. Would you expect to see the same
curve from data collected in a developing (i.e., under-developed) country? What might the differences be,
if any?
Resize as needed.
Part II:
Where To Go: Go to the Demographics Lab at Annenberg Learner: https://www.learner.org/courses/envsci/interactives/demographics/
Instructions
Review the section on Age Structure, Population Growth, and Economic Development in the reading for
Unit II. Familiarize yourself with the age structure diagrams and know what the general shapes represent
(rapid growth, slow growth, stabilized growth, and negative growth)
Open the Annenberg Demographics Lab page (click the OPEN SIMULATOR link).
On the Annenberg Demographics Lab page, you will see a pyramid-shaped age structure diagram in the
middle of your screen and a population curve to the left of your screen. At the top of the page, the “Lesson” may need to be changed to “Population Momentum” and the default “Country” should be “Nigeria:
182 M.”
The population curve to the left is constructed with population (in millions) on the Y-axis and year on the
X-axis. The black diamond denotes where the population is as of 2015. The age structure diagram in center screen is constructed with population (in millions) along the X-axis and age brackets along the Y-axis.
The red bars to the right represent female individuals and blue bars represent males. Familiarize yourself
with both the graph and the chart before you continue.
Answer each questions in complete sentences in as much detail as possible.
Activity and Questions
China
Instruction: Go to “Country,” and select “China: 1.36 B.” The gray “Vital Rates” box will show the birth
rate (1.52 per woman) and death rate (1.05% per year) for the year 2015.
(Questions: 6pts each)
6. Based on what you know about the different shapes of the age structure diagrams, what kind of growth
is China’s population is experiencing?
Resize as needed.
7. In 2015, which two age brackets have the highest number of individuals?
Resize as needed.
Instruction: Now click the green “Run” button, and watch the changes that happen through the year
2050 (the simulator will stop at 2050 automatically).
8. In 1979, China implemented the well-known One Child Policy in an effort to slow an exploding population. Looking at the population curve and the changes in the age structure diagram through 2050, what
were the results of the policy? Did it work? How do you know?
Resize as needed.
Instruction: Click the green “Run” button again, and watch the changes that happen through the year
2100 (the simulator will stop at 2100 automatically).
9. If the One Child Policy is kept in place through 2100 and birth and death rates stay the same, how
does the age structure of the population change? Why might this become a problem in an industrialized
society?
Resize as needed.
Instruction: Click ”Reset” and then click the “Birth” tab, and click the “up 5%” button seven times to
where the birth rate is about 2.12-2.15 per woman. Click apply, and run the simulator through the year
2200.
10. All other parameters being consistent what does the age structure diagram’s pattern tell us about
China’s population if birth rates are raised to 2.15 per woman through the year 2200?
Resize as needed.
USA
Instruction: Let’s change countries now. Go to “Country” at the top of the page, and click “USA: 321 M.”
Click “Run” twice to cycle forward to the year 2100.
11. Given the current birth rate of 1.98 per woman in the U.S. and a 1.36% per year death rate, what kind
of pattern do we see in the age structure diagram through the year 2100? Is our population declining or
increasing? Is it generally stable?
Resize as needed.
Instruction: Click “Reset” and increase the birth rate by 5% to 2.08 per woman (Do not forget to click
“Apply”). Run the simulator through 2100.
12. What does this slight change do to the U.S. population? Is it generally stable or unstable by 2100?
Resize as needed.
Instruction: Lastly, click on each country in the drop-down menu at the top of the page, and look at the
2015 default age structure diagram for each.
13. Which two countries’ default diagrams for 2015 best represent rapid population growth?
Resize as needed.
For Your Own Enrichment: Feel free to play with the simulator after you have finished this assignment.
There are other parameters that can be adjusted to cause changes in the population age structure diagrams. The data that drives the simulator is mostly accurate, and it is fun to make adjustments and view
the outcomes over time.
UnitII_LessonPresentation_Part2
8/3/2018
Slide 1
Unit II: Population Ecology: Population Growth and Regulation
Unit Learning Outcomes
2.1 Examine the concept of population demography and the methods by which population
demographics are researched and described.
2.2 Compare reproductive strategies and population growth models.
2.3 Identify and describe factors that limit population growth.
Course Learning Outcome
2. Describe the various factors that affect population growth regulation.
Slide 2
Single Versus Multiple Reproductive Events
Some life history traits, such as fecundity, timing of reproduction, and parental care, can be
grouped together into general strategies that are used by multiple species. Semelparity occurs
when a species reproduces only once during its lifetime and then dies. Such species use most of
their resource budget during a single reproductive event, sacrificing their health to the point that
they do not survive. Examples of semelparity are bamboo, which flowers once and then dies, and
the Chinook salmon (Figure a), which uses most of its energy reserves to migrate from the ocean
to its freshwater nesting area, where it reproduces and then dies. Scientists have posited
alternate explanations for the evolutionary advantage of the Chinook’s post-reproduction death: a
programmed suicide caused by a massive release of corticosteroid hormones, presumably so the
parents can become food for the offspring, or simple exhaustion caused by the energy demands
of reproduction; these are still being debated (OpenStax, 2017).
Iteroparity describes species that reproduce repeatedly during their lives. Some animals are able
to mate only once per year, but survive multiple mating seasons. The pronghorn antelope is an
example of an animal that goes into a seasonal estrus cycle (“heat”): a hormonally induced
physiological condition preparing the body for successful mating (Figure b). Females of these
species mate only during the estrus phase of the cycle. A different pattern is observed in
primates, including humans and chimpanzees, which may attempt reproduction at any time
during their reproductive years, even though their menstrual cycles make pregnancy likely only a
few days per month during ovulation (Figure c) (OpenStax, 2017).
The (a) Chinook salmon mates once and dies. The (b) pronghorn antelope mates during specific
times of the year during its reproductive life. Primates, such as humans and (c) chimpanzees,
may mate on any day, independent of ovulation. (credit a: modification of work by Roger Tabor,
USFWS; credit b: modification of work by Mark Gocke, USDA; credit c: modification of work by
“Shiny Things”/Flick (OpenStax, 2017).
Slide 3
Check for Learning
,
1 of 12
UnitII_LessonPresentation_Part2
8/3/2018
Which of the following is associated with multiple reproductive episodes during a species’
Fill in the circle of the correct answer:
 A) Semiparity
 B) Iteroparity
 C) Semelparity
 D) Fecundity
Knowledge Check
Slide 4
Environmental Limits to Population Growth
Although life histories describe the way many characteristics of a population (such as their age
structure) change over time in a general way, population ecologists make use of a variety of
methods to model population dynamics mathematically. These more precise models can then be
used to accurately describe changes occurring in a population and better predict future changes.
Certain models that have been accepted for decades are now being modified or even abandoned
due to their lack of predictive ability, and scholars strive to create effective new models
(OpenStax, 2017).
Exponential Growth
Charles Darwin, in his theory of natural selection, was greatly influenced by the English
clergyman Thomas Malthus. Malthus published a book in 1798 stating that populations with
unlimited natural resources grow very rapidly, and then population growth decreases as
resources become depleted. This accelerating pattern of increasing population size is called
exponential growth.
The best example of exponential growth is seen in bacteria. Bacteria are prokaryotes that
reproduce by prokaryotic fission. This division takes about an hour for many bacterial species. If
1000 bacteria are placed in a large flask with an unlimited supply of nutrients (so the nutrients will
not become depleted), after an hour, there is one round of division and each organism divides,
resulting in 2000 organisms—an increase of 1000. In another hour, each of the 2000 organisms
will double, producing 4000, an increase of 2000 organisms. After the third hour, there should be
8000 bacteria in the flask, an increase of 4000 organisms. The important concept of exponential
growth is that the population growth rate—the number of organisms added in each reproductive
generation—is accelerating; that is, it is increasing at a greater and greater rate. After 1 day and
24 of these cycles, the population would have increased from 1000 to more than 16 billion. When
the population size, N, is plotted over time, a J-shaped growth curve is produced (Figure)
(OpenStax, 2017).
The bacteria example is not representative of the real world where resources are limited.
Furthermore, some bacteria will die during the experiment and thus not reproduce, lowering the
growth rate. Therefore, when calculating the growth rate of a population, the death rate (D)
(number organisms that die during a particular time interval) is subtracted from the birth rate (B)
(number organisms that are born during that interval). This is shown in the following formula:
Slide 5
,
2 of 12
UnitII_LessonPresentation_Part2
8/3/2018
The birth rate is usually expressed on a per capita (for each individual) basis. Thus, B (birth rate)
= bN (the per capita birth rate “b” multiplied by the number of individuals “N”) and D (death rate)
=dN (the per capita death rate “d” multiplied by the number of individuals “N”). Additionally,
ecologists are interested in the population at a particular point in time, an infinitely small time
interval. For this reason, the terminology of differential calculus is used to obtain the
“instantaneous” growth rate, replacing the change in number and time with an instant-specific
measurement of number and time (OpenStax, 2017).
Notice that the “d” associated with the first term refers to the derivative (as the term is used in
calculus) and is different from the death rate, also called “d.” The difference between birth and
death rates is further simplified by substituting the term “r” (intrinsic rate of increase) for the
relationship between birth and death rates
The value “r” can be positive, meaning the population is increasing in size; or negative, meaning
the population is decreasing in size; or zero, where the population’s size is unchanging, a
condition known as zero population growth. A further refinement of the formula recognizes that
different species have inherent differences in their intrinsic rate of increase (often thought of as
the potential for reproduction), even under ideal conditions. Obviously, a bacterium can reproduce
more rapidly and have a higher intrinsic rate of growth than a human. The maximal growth rate
for a species is its biotic potential, or rmax, thus changing the equation to as shown below:
Slide 6
Check for Learning
The maximal growth rate for a species is called its __________.
Fill in the circle of the correct answer:
 A) limit
 B) carrying capacity
 C) biotic potential
 D) exponential growth pattern
Knowledge Check
Slide 7
Logistic Growth
Exponential growth is possible only when infinite natural resources are available; this is not the
case in the real world. Charles Darwin recognized this fact in his description of the “struggle for
existence,” which states that individuals will compete (with members of their own or other
species) for limited resources. The successful ones will survive to pass on their own
characteristics and traits (which we know now are transferred by genes) to the next generation at
a greater rate (natural selection). To model the reality of limited resources, population ecologists
developed the logistic growth model (OpenStax, 2017).
,
3 of 12
UnitII_LessonPresentation_Part2
8/3/2018
Slide 8
Carrying Capacity and the Logistic Model
In the real world, with its limited resources, exponential growth cannot continue indefinitely.
Exponential growth may occur in environments where there are few individuals and plentiful
resources, but when the number of individuals gets large enough, resources will be depleted,
slowing the growth rate. Eventually, the growth rate will plateau or level off (Figure). This
population size, which represents the maximum population size that a particular environment can
support, is called the carrying capacity, or K (OpenStax, 2017).
The formula we use to calculate logistic growth adds the carrying capacity as a moderating force
in the growth rate. The expression “K – N” is indicative of how many individuals may be added to
a population at a given stage, and “K – N” divided by “K” is the fraction of the carrying capacity
available for further growth. Thus, the exponential growth model is restricted by this factor to
generate the logistic growth equation:
Notice that when N is very small, (K-N)/K becomes close to K/K or 1, and the right side of the
equation reduces to rmaxN, which means the population is growing exponentially and is not
influenced by carrying capacity. On the other hand, when N is large, (K-N)/K come close to zero,
which means that population growth will be slowed greatly or even stopped. Thus, population
growth is greatly slowed in large populations by the carrying capacity K. This model also allows
for the population of a negative population growth, or a population decline. This occurs when the
number of individuals in the population exceeds the carrying capacity (because the value of (KN)/K is negative).
A graph of this equation yields an S-shaped curve (Figure), and it is a more realistic model of
population growth than exponential growth. There are three different sections to an S-shaped
curve. Initially, growth is exponential because there are few individuals and ample resources
available. Then, as resources begin to become limited, the growth rate decreases. Finally, growth
levels off at the carrying capacity of the environment, with little change in population size over
time.
Slide 9
Check for Learning
The population size of a species capable of being supported by the environment is called its
__________.
Fill in the circle of the correct answer:
 A) limit
 B) carrying capacity
 C) biotic …