Name: Date:

Biology 11: Population Ecology

Learning Objectives:

Describe the stages a population goes through as it increases in size, with reference to terms such as

exponential growth, logistic growth, cyclic growth, carrying capacity, steady state.

Describe density-dependent and density-independent factors that limit and control population growth

Collect, display, and interpret data

Describe the process of ecological succession, with reference to terms such as pioneer species and climax

community

Introduction: Read Text Pages 723 and section 36.1 on page 724 and use the information contained to

answer the questions below.

Create a diagram to show the food web that the penguin is involved in. Don’t forget the decomposers.

1. Circle the diagram below illustrating a population. Explain you answer.

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Biology 11: Population Ecology 1

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2. What is Population Ecology?

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3. What do population ecologists study?

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4. Choose one of the applications of population ecology and find one example of how it has been used in

the real world. Example: Identifying and and attempting to save the endangered cichlids in Lake

Victoria.

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Population Size: Influencing Paramaters

-The size of a population continually changes due to various factors that will affect the density of a

population. The numbers in a population will either increase or decrease depending on the following

population parameters.

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1. Use the formula Population Size= (N+I) – (M+E) to create a decreasing population.

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2. Use the formula to create an increasing population.

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-Aside from the above, two other important factors influencing population growth are:

a) The condition of organisms in the population.

b) The condition of the environment.

3. Two important characteristics of populations are the distribution (dispersion) and density of organisms.

(Page 724). The diagram below illustrates both of these concepts, differentiate density and dispersion and

define these two terms.

a) Density _________________________________

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b) Dispersion ______________________________

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Techniques for Estimating Population Density

1. Sample Plot Method counts the number of organisms of the study species in plots of known size. The

data found is then used to estimate the entire population size.

a) With what type of organisms is this method appropriate?

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b) The formula used in the Sample Plot Method is:

Population Density = Number of Individuals in Sample Plots

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Total Area of all Sample Plots

c) Your Sample Plot Analysis (show all your calculations!)

Location: ____________________________________________________________________________

Sample Plot Area: _____________________________________________________________________

Species of Study: _____________________________________________________________________

Individuals Counted: ___________________________________________________________________

Estimated Population Density: ____________________________________________________________

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d) After conducting this study, brainstorm some of the limitations of the Sample Plot Method.

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2. Mark-Recapture Method uses two trapping events to estimate the size of a population. First, the study

area is determined and a trap is set. All animals caught in this trap are marked and released. Later, the

traps are set again and the proportion of marked to unmarked animals captured in the second trapping

provides an estimate of the number of individuals in a population.

a) With what type of organisms is this method appropriate?

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b) The formula used in the Mark-Recapture Method is:

Population Density = M x C

R

M= Total number of animals captured and marked in the first trapping event

C= Total number of animals captured in the second trapping event

R= Number of animals captured in the first trap that were recaptured in the second trapping event

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c) Your Sample Plot Analysis (show all your calculations!)

Location: ____________________________________________________________________________

Sample Plot Area: _____________________________________________________________________

Species of Study: _____________________________________________________________________

Individuals Counted in First Trap: _________________________________________________________

Individuals Counted in Second Trap: _______________________________________________________

Individual Recaptured in the Second Trap: __________________________________________________

Estimated Population Density: ____________________________________________________________

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d) After conducting this study, brainstorm some of the limitations of the Sample Plot Method.

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Techiques for Estimating Population Composition: Life Tables

-A population is made up of individuals who are at different stages in their lifespan. Survivorship Curves

allow population ecologists to estimate how many members of an original study group are still alive at

different time intervals.

1. Complete Activity 36.3: Investigating Survivorship Curves (found on the text website).

2. Afterwards, identify the characteristics of Type I, II and III Surviviorship Curves and provide an

example of an organism demonstrating each life history pattern (these must be different than the

organisms on the graph below).

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a) Type 1 ____________________________________________________________________________

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b) Type II ____________________________________________________________________________

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c) Type III ___________________________________________________________________________

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Patterns of Population Growth

-Populations grow at different rates, depending on the abiotic and biotic factors at work in their

environment. All population vary in size according to a per capita rate of increase.

-The highest possible rate of per capita increase for a population is called the Biotic Potential.

1. Environmental Resistance is the environmental conditions that prevent a population from achieving

its biotic potential. Examples of these limiting factors are:

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2. Limiting factors can be Density Dependent or Density Independent. Differentiate between the two

(Text 36.5).

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3. Because of these limiting factors, the growth of many populations levels off and a Logistic Growth

Pattern develops (as illustrated by the Fur Seal growth curve on text 727).

-Draw a Logistic Growth Curve and label and define Slow Growth, Exponential Growth and Carrying

Capacity (Population Equilibrium). Label the x-axis Number of Individuals, y-axis as Time and be sure

to use a pencil and a ruler.

-Complete the Lesson of the Kaibab activity.

-For information on the current condition of the Kaibab Deer, check out

http://www.youtube.com/watch?v=AiGh6YRRR_s

4. Another method for estimating population growth is the Exponential Growth Model. What is this?

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-Examine the exponential growth of rabbits graph on text 728.

-Draw an Exponential Growth Curve and label the x-axis Population Size, y-axis Time. Explain what the

shape of the curve reveals about this type of growth (text 728). Use a pencil and a ruler.

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Human Population Growth 36.9

-In the following activities you will read about and explore the nature of the human population’s growth.

In doing so, the concepts and terms discussed above will be applied.

1. View the website http://www.ibiblio.org/lunarbin/worldpop and have a look at the human population

when you were born!

2. Complete activity 36.9 Human Population Growth on the text website. While doing so, answer the

questions below.

a) How did improvements in agriculture affect human population growth?

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b) What caused the kink in the curve around 1400 AD?

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c) What do you think led to the greatest increase in human population growth?

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d) What was the factor that encouraged human population growth after it reached 3 billion?

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e) What factors may eventually lead to a decline in human population growth?

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Human Population Impact on the Natural World

1. Human activity affects three levels of biodiversity. Define each term.

a) Genetic Diversity ____________________________________________________________________

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b) Species Diversity ____________________________________________________________________

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c) Ecosystem Diversity

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2. Ecological Footprint is one way to understand resource availability and how they are being used by

human populations. Explain in more detail what an ecological footprint is below using text 734 to 735 as

a reference.

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a) Calculate your own Ecological Footprint at http://www.royalsaskmuseum.ca/exhibits-galleries/life-

sciences-gallery/human-factor

-How do you compare with people:

a) In Canada? _________________________________________

b) The World? ________________________________________

-How many Earths would be required to support the human population if

everyone lived like you? _____

-What can you do to reduce your ecological footprint?

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