Old Exam 2

Short Answer Questions: (5 points each)

 

1. Give a biological example of a species that exhibits logistic population growth.

   

2. True or False? When comparing the exponential and geometric population growth models of population growth, the exponential and geometric rates of population growth are related as follows: ln r = λ.

  

3. Give two pieces of evidence for genome duplication in the Hawaiian Silverswords relative to the North American Tarweeds.

 

4. True or False? Regulatory genes evolved faster in the North American Tarweeds than in the Hawaiian Silverswords.

   

5. In the logistic population growth model, does population density, N, increase, decrease or remain constant, if

N > K?

   

6. In the Werner/Gilliam study with juvenile bluegill sunfish, what affect does increasing bass density have on the body size at which a juvenile bluegill sunfish switches from the near shore to open water habitat?

   

7. In the Werner/Gilliam study with juvenile bluegill sunfish, would you expect juveniles in ponds with low bass density to reach larger, smaller, or roughly the same body size as juveniles in ponds with high bass density? Why?

   

8. Which pair-wise interspecific ecological interactions are associated with the following pairs of signs: (-, -), (+, -), (+, +)?

   

9. What effect does interspecific competition have on each species dN/dt?

   

10. True or False? When two competing species are in stable coexistence, they each achieve lower carrying capacities than they would if each species were alone.

Essay Questions: (25 points each)

 

1. Life History Evolution: (25 pts) Consider the life history model, Rx = mx + sx, x+1 Rx+1.

 

a. (6 pts) Define the terms, x, Rx ,  mx ,  sx, x+1 and Rx+1 in the equation.

 

   

b. (6 pts) Draw a diagram of a life cycle, and place the terms, mx, sx, x+1 and Rx+1 , in the appropriate places on your diagram.

 

   

c. (7 pts) What is Williams' tradeoff in terms of the above model? Where is it represented on your graph? What is a biological example of Williams' tradeoff that we had in class?

 

   

d. (6 pts) What is Lack's tradeoff in terms of the above model? Where is it represented on your graph? What is a biological example of Lack's tradeoff that we had in class?

 

2. Population Biology: (25 pts). Consider density independent and density dependent population growth.

 

a. (8 pts) Describe the differences between density-independent and density-dependent population growth models, using the exponential growth model and the logistic models as your examples. Write out the equations for each model, and define the terms.

 

 b. (9 pts) Draw a graph of exponential population growth where the axes are population density (N) vs. time (t). Include on your graph the cases when population growth is positive, zero, and negative, and label the cases with the appropriate values for r.

    

c. (8 pts) Draw another graph of N vs. t for logistic population growth and include the cases of when N0 < K and N0 > K.