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NS 1021A: Introduction to Biology: Organisms and the Environment

Summer '08 Syllabus: Day 16
Tuesday, July 22

In-Class:

  • Student Case studies (two more)
  • Lecture/discussion: Population dynamics, communities and competition

Homework:


For Tuesday, July 22
Read ch 2.8-2.10, pages 33 - 38, and ch 32.1-32.6, pages 703 - 713.

Answer the following questions (also available as a Word document in the class shared folder):

  1. What is the difference between population size and population density?
     
  2. Give an example of a population which has a uniform dispersion, and one which has a clumped dispersion.
     
  3. Why don't populations continue with exponential growth indefinitely?
     
  4. Give an example of a density-independent effect and a density-dependent effect.
     
  5. Are humans an r-selected population or a K-selected population?
     
  6. The proportion of older individuals in the United State's population has increased over the past 50 years.  Is this likely to mean an increasing population growth rate, or a decreasing population growth rate?
     
  7. What are the conditions that redwood trees create for other members of the redwood community?
     
  8. What are some conditions characteristic of the deciduous forest community around Landmark College?
     
  9. What is the difference between a habitat and a niche?
     
  10. Why can two organisms not occupy exactly the same niche?
     
  11. Look at the picture on page 713.  Are any of the warblers using their full fundamental niche?

Test 2 question 5 due (see below)

"Mussel Beach" due

For Wednesday, July 23
Read ch 32.7-32.12, pages 714 - 728.

Answer the following questions (also available as a Word document in the class shared folder):

  1. What are the three major different kinds of symbiotic relationships?
     
  2. Look at the predator-prey cycle graph and read the caption below it on page 719.   Does it look like the population of snowshoe hares is the only determining factor for the size of the lynx population?
       
  3. Give an example of a plant chemical defense which keeps humans away.
     
  4. Why is it important for Batesian mimics to be rare relative to the organisms they are mimicking?
     
  5. What is the difference between primary and   secondary succession?
     
  6. Why are tropical rain forests among the most Biodiverse regions on earth?
     
  7. Why are ecosystems with high biodiversity more stable than ecosystems with lower biodiversity?

Test 3 question 1 due (see below)

Human Evolution lab (Skull lab) due

For Thursday, July 24
Read ch 2.6-2.7, pages 31-32 and ch 31.1-31.2, pages 677-682.

Answer the following questions (also available as a Word document in the class shared folder):

  1. List the levels of ecological organization and define each.
     
  2. How, in general terms, does energy flow through ecosystems - that is, what is the ultimate source of energy for life, and what is the path of that energy through living things?
     
  3. What is the difference between a habitat and an ecosystem?
     
  4. Name three producers and three consumers.
     
  5. Name one organism in each of trophic levels 1, 2, and 3.
     
  6. Why does a food chain typically have only three or four steps?

Test 3 question 2 due

Test 2 question 5:

Due Tuesday, July 22
20 points.
  • Imagine and describe an evolutionary scenario.  You may choose the evolution of a real organism, or make one up.  Explain how natural selection worked on your organism to change it over time.  What variations exist in the species?  Describe specific selective pressures, and what phenotypes were affected.  Pressures may be from the physical environment or due to other organisms in the ecosystem, or a combination.  Describe what isolating mechanism or mechanisms and what type of selection led to the evolution of this species.  Minimum of one page, about 300 words, maximum of 3 pages, about 900 words.  Drawings are welcome, but they must be explained.

Test 3 question 1:

Due Wednesday, July 23
8 points.
  • Using the pictures handed out in class for this question, answer the following:
    The drawings show a habitat before and after a new organism moved in.   Using the drawings as an example, explain the concepts of fundamental niche, realized niche, niche overlap, and resource partitioning.

Test 3 question 2:

Due Thursday, July 24
8 points.
  • How does evolution connect to ecology?  Does the environment directly cause changes in an organism over time?  If so, how?  If not, what does cause changes in an organism?  Include in your answer a discussion of both ecological niches and coevolution.  (20 points)
 

Vocabulary:

population
population size
population density
population dispersion
population growth
carrying capacity
exponential growth model
logistic growth model
sigmoid growth curve
density dependent effects
density independent effects
demography 		community
niche
competition
interspecific competition
fundamental niche
realized niche
competitive exclusion
niche overlab
resource partitioning
sympatric species
allopatric species
character displacement  		  

   

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