Download Reading Guide 06 - Population Ecology

Biology 100 – Winter 2013
Reading Guide 06 – Population Ecology
Reading: Ch 21 in Biology for a Changing World, by Shuster, Vigna, Sinha, and Tontonoz (2012)
Directions: Fill out the reading guide as you read. Again, the reading guide is designed to help you take
notes from your reading. Along the way, I will ask you some Critical Thinking questions that are
designed to help stimulate your thinking as to how the concepts and vocabulary from the class can be
used to help explain our Essential Question.
As you read, keep our Essential Question in mind:
How is this information helping me to explain how an epidemic can get started?
_________________________________________________________________________________________
Think Back: Look back at Reading Guide 02 – Epidemiology question 7. The two main branches that
epidemiology can be considered to be a part of are microbiology and ecology. While we’ll be learning a lot
more about microbes in Unit 02, in this reading guide, we will explore some basic concepts of ecology that will
help us to understand how an epidemic can get started.
So you may have looked at the chapter and said to yourself, “WOLVES and MOOSE?!?! Why am I learning
about wolves and moose when I’m studying infectious disease?” Hopefully, what you’ll find is that by learning
about the POPULATIONS of wolves (predator) and moose (prey) you’ll be able to reapply those biological
concepts to the POPULATIONS of microbes (predator) and humans (prey)….Let’s get started!
1. From pg 414, fill in the following blanks to finish the quote: “Begun in 1958, the Isle Royale
____________ and _____________ study is the longest-running _____________________________
study in the world.”
2. Write down their definition of Ecology:
Critical Thinking 1: The interactions between what two different organisms are we studying as we try to
understand how a pertussis epidemic can get started?
3. “Ecologists study organisms at different levels:” Write down the 4 levels at which ecologists study
organisms and describe them (Infographic 21.1)
1.
2.
3.
4.
Critical Thinking 2: At which levels of ecology do you think we would want to study a disease epidemic
and why?
4. What is their definition of “Distribution Pattern”?
5. What are the three main types of distribution patterns? Draw a box as they do in Infographic 21.3 and,
using dots, draw a representation of each type of pattern.
1.
2.
3.
Critical Thinking 3: Which distribution pattern do you think would spread a communicable disease
throughout a whole population by direct contact transmission the fastest? Why do you think that?
6. What is their definition of “Growth Rate”?
7. Describe the two different types of population growth (these are called growth models):
1.
2.
8. What is “Carrying Capacity”?
9. Redraw Infographic 21.4 here to help you visualize the difference between the two different types of
population growth models.
10. Why does a population’s growth seem to “fluctuate” (go up and down) around the carrying capacity in
the logistic growth pattern in what is called a “boom and bust” cycle (page 420)?
11. Explain why the wolf (predator) and moose (prey) population growth curves go through a “boom and
bust” growth cycle (p 421).
Critical Thinking 4: Many of you noticed that the CDC said, “Pertussis is naturally cyclical in
nature, with peaks in disease every 3-5 years.” (from the “Whooping Cough Outbreak: Top 10
Things You Should Know” at the PBSNewsHour Website
(http://www.pbs.org/newshour/rundown/2012/08/whooping-cough-outbreak-top-10-things-you-shouldknow.html)). WHY does it peak every 3-5 years????
If we think about a disease-causing microbe (a pathogen) as the predator and humans (the reservoir) as
the prey, can you use the wolf-moose “boom and bust” growth cycle as a way to explain it? How?
12. What kinds of clues do these ecological detectives use to follow the population dynamics (changes) of
the health of the moose and wolf populations?
Critical Thinking 5: What kinds of clues do epidemiologists (ecological detectives!) use to follow the
population dynamics (changes) of a disease-causing microbe?
13. What is “population density”?
Critical Thinking 6: Let’s do some math! How would you solve this problem? Please show your work!
 The area of Seattle can be said to be A m2. The population of Seattle at Time = 0 can be said to be N
number of people. Using A and N, what is the population density of Seattle at Time = 0?
 If the population of Seattle grows to be 2N at Time = 1, what is the population density of Seattle at
Time = 1?
 Can you say that the population of Seattle is proportional to the population density of Seattle? Why?
14. What is the definition of a “density-dependent factor”?
15. What is the definition of a “density-independent factor?”
Critical Thinking 7: Look back to Reading Guide 02 and the different ways that diseases can be
transmitted. Focus in on Direct transmission and indirect transmission. Can you make an argument for
whether these modes of transmission are density-dependent or density-independent?
Summary on page 428 is helpful to review Population Ecology concepts.