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BIO102: Introduction to Evolutionary Biology and Ecology

Unit 7: Population Ecology   We will now learn about ecology, the study of the interactions between organisms and their environments.  Ecology is not the same as environmental studies or environmentalism.  It is instead closely related to the study of evolution and genetics and other biology topics.  As you might imagine, the study of organisms and the environment can be very complicated since we not only have to keep track of all the organisms within an environment, but their changing environments as well.  The concepts of ecology are thus not as explicitly defined as other subjects in biology.  They are generalized explanations of natural phenomenon rather than specific names and functions of molecules or cell structures.  A lot of the principles of ecology involve some algebra since they deal with large numbers and variables.  Be sure to brush up on your math to fully understand this unit!

Unit 7 Time Advisory
This unit should take approximately 6.75 hours to complete.
 
☐    Subunit 7.1: 1.5 hours
 
☐    Subunit 7.2: 1 hour
 
☐    Subunit 7.3: 2.5 hours
 
☐    Subunit 7.4: 1.25 hours

☐    Assessment: 0.5 hours

Unit7 Learning Outcomes
Upon completion of this unit, the student will be able to: - Understand what factors determine populations’ distribution and abundance. - Distinguish between logistic and exponential growth and know when each type of growth is expected to occur. - Identify factors that influence carrying capacity understand how carrying capacity for a single population can change over time depending on the abundance of resources. - Demonstrate an understanding of the effects competition and predation have on populations’ sizes, distribution, and niches. - Distinguish between types of symbiosis (parasitism, commensalism, mutualism) and understand which species derive benefits or disadvantages from each type of interaction. - Identify situations in which succession will and will not occur. - Understand how different types of organisms will be present at different stages of succession.

7.1 Populations: Range, Spacing, Size and Population Change   - Lecture: YouTube: University of California at Berkeley: Mary Power’s “Population Biology” Link: YouTube: University of California at Berkeley: Mary Power’s “Population Biology” (YouTube)

 Instructions: Watch this lecture, starting at the 9-minute mark.
 Please note that although the lecture is labeled “Species
Interactions,” the professor was one day behind in her syllabus, so
the lecture in fact deals with population distributions and size.  

 Watching this lecture and pausing to take notes should take
approximately 1 hour.  

 Terms of Use: This video is licensed under a [Creative Commons
Attribution-NonCommercial-NoDerivativeWorks 3.0
License](http://creativecommons.org/licenses/by-nc-nd/3.0/).  It is
attributed to Mary Powers and the University of California at
Berkeley's [Webcast.Berkeley](http://webcast.berkeley.edu/).
  • Reading: Dr. Michael J. Farabee’s Online Biology Book: Chapter 55: “Population Ecology” Link: Dr. Michael J. Farabee’s Online Biology Book“Chapter 55: Population Ecology” (HTML)

    Instructions: Read from the second section, “Population Growth,” through the end of the page. Population growth is limited or controlled by the carrying capacity (abbreviated as K) of a population.  A population’s carrying capacity is the number of individuals that can be supported by the resources available to that population.  If, for example, there is only so much vegetation in an area for that area’s moose population to eat, then the carrying capacity of moose would be the number of individuals that would have enough vegetation to survive in that area.  Carrying capacities can change depending on the existence and abundance of resources.  Some limiting resources include food, water, appropriate habitat, and appropriate territory sizes.

    Reading this section and taking notes should take approximately 30 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

7.2 Population Change   - Lecture: Yale University: Stephen C. Stearns’ Principles of Evolution, Ecology, and Behavior: “Population Growth: Density Effects” Link: Yale University: Stephen C. Stearns’ Principles of Evolution, Ecology, and Behavior“Population Growth: Density Effects” (YouTube)

 Also available in:  
 [MP4](http://www.archive.org/details/PopulationGrowthDensityEffects)  

[MP3](http://oyc.yale.edu/ecology-and-evolutionary-biology/eeb-122/lecture-26)  
 [iTunes U
Audio](http://deimos3.apple.com/WebObjects/Core.woa/Browse/yale.edu.2413658053.02413658061.2563519540?i=1975714050)  
 [iTunes U
Video](http://deimos3.apple.com/WebObjects/Core.woa/Browse/yale.edu.2413658053.02471197475.2688204969?i=1898632259)  

 Instructions: Please click on the link above and watch the lecture.
 This lecture covers the material in sub-subunits 7.2.1 through
7.2.3.  Please note that populations demonstrating density-dependent
growth and leveling out at carrying capacity (K) are generally
referred to as showing “logistic” growth (on a graph, an S-shaped
curve), whereas populations with density-independent growth  exhibit
“exponential” growth (on a graph, a J-shaped curve).  

 Watching this lecture and pausing to take notes should take
approximately 1 hour.  

 Terms of Use: This resource is licensed under a [Creative Commons
Attribution-NonCommercial-ShareAlike 3.0
License](http://creativecommons.org/licenses/by-nc-sa/3.0/us/).  It
is attributed to Stephen C. Stearns and Yale University's [Open Yale
Courses](http://oyc.yale.edu/).  The original version can be found
[here](http://oyc.yale.edu/ecology-and-evolutionary-biology/eeb-122/lecture-26).

7.2.1 Cost of Reproduction   Note: This sub-subunit is covered by the materials under subunits 7.1 and 7.2.

7.2.2 Exponential Growth Model   Note: This sub-subunit is covered by the materials under subunits 7.1 and 7.2.

7.2.3 Logistic Growth Model   Note: This sub-subunit is covered by the materials under subunits 7.1 and 7.2.  Population growth is limited or controlled by the carrying capacity (abbreviated, K) of a population.  A population’s carrying capacity is the number of individuals that can be supported by the resources available to that population.  If, for example, there is only so much vegetation in an area for that area’s moose population to eat, then the carrying capacity of moose would be the number of individuals that would have enough vegetation to survive in that area.  Carrying capacities can change depending on the existence and abundance of resources.  Some limiting resources include food, water, appropriate habitat, and appropriate territory sizes.

7.3 Communities   7.3.1 Individualistic vs. Holistic Theories   - Lecture: Yale University: Stephen C. Stearns’ Principles of Evolution, Ecology, and Behavior: “Interspecific Competition” Link: Yale University: Stephen C. Stearns’ Principles of Evolution, Ecology, and Behavior“Interspecific Competition” (YouTube)

 Also available in:  
 [MP4](http://www.archive.org/details/InterspecificCompetition)  

[MP3](http://oyc.yale.edu/ecology-and-evolutionary-biology/eeb-122/lecture-27)  
 [iTunes U
Video](http://deimos3.apple.com/WebObjects/Core.woa/Browse/yale.edu.2413658053.02471197475.2681545010?i=1501029150)  
 [iTunes U
Audio](http://deimos3.apple.com/WebObjects/Core.woa/Browse/yale.edu.2413658053.02413658061.2563519552?i=1223494950)  

 Instructions: Please click on the link above and watch the lecture.
 This lecture covers the material in sub-subunits 7.3.2 through
7.3.4.  

 Watching this lecture and pausing to take notes should take
approximately 1 hour.  

 Terms of Use: This resource is licensed under a [Creative Commons
Attribution-NonCommercial-ShareAlike 3.0
License](http://creativecommons.org/licenses/by-nc-sa/3.0/us/).  It
is attributed to Stephen C. Stearns and Yale University's [Open Yale
Courses](http://oyc.yale.edu).  The original version can be found
[here](http://oyc.yale.edu/ecology-and-evolutionary-biology/eeb-122/lecture-27).

7.3.2 Fundamental Niche   Note: This sub-subunit is covered by the material under sub-subunit 7.3.1.

7.3.3 Realized Niche   Note: This sub-subunit is covered by the material under sub-subunit 7.3.1.  It is important to understand that the “fundamental niche” is the niche a population will achieve under ideal circumstances, that is, without competition for resources or predation.  A “realized niche” refers to the actual niche in which a population lives.

7.3.4 Competition   - Web Media: Public Broadcasting System's Evolution Library: “Coral Reef Connections” Link: Public Broadcasting System's Evolution Library: “Coral Reef Connections” (Flash)

 Instructions: Please click on the link above and read the
introductory page of this interactive webpage.  Then click on “Dive
Now” link to enter the virtual reef.  You can “swim” through the
reef by moving your cursor towards the edge of the image.  You can
also change the type of relationship described by checking one of
the three boxes in the lower right-hand corner of the page:
“Predation and Parasitism,” “Competition,” or “Commensalism and
Mutualism.”  Move from one “Reef Zone” to another (“Reef
Front,” “Reef Crest,” “Reef Flat,” and “Reef Cay”) by clicking on
the square above the map image on the right.  This webpage will help
you visualize examples of competition, predation, and symbiosis in
various areas and aspects life in a coral reef.  This resource
covers material in sub-subunits 7.3.5, and 7.4.1.  

 Reading this webpage and completing this activity should take
approximately 30 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

7.3.5 Predation   - Lecture: Yale University: Stephen C. Stearns’ Principles of Evolution, Ecology, and Behavior: “Ecological Communities” Link: Yale University: Stephen C. Stearns’ Principles of Evolution, Ecology, and Behavior“Ecological Communities” (YouTube)

 Also available in:  
 [MP4](http://www.archive.org/details/EcologicalCommunities)  

[MP3](http://oyc.yale.edu/ecology-and-evolutionary-biology/eeb-122/lecture-28)  
 [iTunes U
Audio](http://deimos3.apple.com/WebObjects/Core.woa/Browse/yale.edu.2413658053.02413658061.2558377799?i=1353558914)  
 [iTunes U
Video](http://deimos3.apple.com/WebObjects/Core.woa/Browse/yale.edu.2413658053.02471197475.2681872603?i=1792788082)  

 Instructions: Please click on the link above and watch the lecture.
 Please note that the terms “trophic cascades” and “trophic levels”
refer to food webs and food chains; “trophic” comes from a Greek
word meaning “food.”  

 Watching this lecture and pausing to take notes should take
approximately 1 hour.  

 Terms of Use: This resource is licensed under a [Creative Commons
Attribution-NonCommercial-ShareAlike 3.0
License](http://creativecommons.org/licenses/by-nc-sa/3.0/us/).  It
is attributed to Stephen C. Stearns and Yale University's [Open Yale
Courses](http://oyc.yale.edu).  The original version can be found
[here](http://oyc.yale.edu/ecology-and-evolutionary-biology/eeb-122/lecture-28).

7.4 Community Interactions   7.4.1 Symbiosis: Parasitism, Commensalism, Mutualism   - Reading: The Saylor Foundation’s “Symbiosis”

Link: The Saylor Foundation’s
[“Symbiosis](http://www.saylor.org/site/wp-content/uploads/2012/09/7.4.1-Symbiosis.pdf)[”](http://www.saylor.org/site/wp-content/uploads/2012/09/7.4.1-Symbiosis.pdf) (PDF)  

 Instructions: Please click on the link above and read the entire
article, which discusses symbiosis in a coral reef.  This reading
will give you a good idea of how many different types of
interactions happen within one ecosystem.  

 Reading this article and taking notes should take approximately 15
minutes.

7.4.2 Succession   - Reading: Dr. Michael J. Farabee’s Online Biology Book: “Chapter 56: Community and Ecosystem Dynamics” Link: Dr. Michael J. Farabee’s Online Biology Book“Chapter 56: Community and Ecosystem Dynamics” (HTML)

 Instructions: Please click on the link above and read the sections
titled “Change in Communities over Time” and “Disturbance of a
Community.”  

 Reading these sections and taking notes should take approximately
15 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

7.4.3 Succession Process   - Reading: Offwell Woodland & Wildlife Trust’s “Ecological Succession” Link: Offwell Woodland & Wildlife Trust’s “Ecological Succession” (HTML)

 Instructions: Click on the link above and follow the links to read
the sections titled “Explanation of Succession,” “Primary
Succession,” “Sand Dunes,” and “Secondary Succession.”  Do not
concern yourself with the specific species described and listed in
“Sand Dunes”; just understand that different types of species with
different characteristics are present at different stages of
succession.  

 Reading these sections and taking notes should take approximately
45 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

Unit 7 Review and Assessment   - Assessment: The Saylor Foundation’s “Unit 7 Review” Link: The Saylor Foundation’s “Unit 7 Review” (PDF)

 Instructions: Please click on the link above and work through the
questions. When you are finished, check your work against The Saylor
Foundation’s [“Unit 7 Review Answer
Key”](http://www.saylor.org/site/wp-content/uploads/2012/11/BIO102_Unit_7_Review-ANSWER-KEY-FINAL.pdf)
(PDF).  

 Completing this assessment should take approximately 30 minutes.
  • Assessment: The Saylor Foundation’s “Unit 7 Assessment” Link: The Saylor Foundation’s “Unit 7 Assessment” (HTML)

    Instructions: Please complete the linked assessment.
     
    You must be logged into your Saylor Foundation School account in order to access this quiz.  If you do not yet have an account, you will be able to create one, free of charge, after clicking the link.