Ecology 203, Exam II, Oct. 22, 1999 Name _______________________ Section I II

Rules: Read carefully, work accurately and efficiently. Note that you don’t have to answer all questions in each section. Good Luck!!! (note: SS = student submission)

Multiple Guess. Complete five. Circle the correct answer. (2 pts each)

  1. The slope of a "Mean Tree Volume vs. Tree Density" graph is usually: [SS]
  1. +1.5
  2. -1.5
  3. 1
  4. 1.6143.....
  5. only a or b
  1. Biological factors that influence an organism's distribution include: [SS]

a) competition

b) predation

c) disease

d) all of the above

e) none of the above

3. What is the most likely explanation for why Thomson’s Gazelles stot? [SS]

a) it is used as an alarm signal

b) it’s a form of social cohesion

c) they are trying to confuse the predator

d) they are trying to appear unprofitable

e) there appears to be no explanation for their behavior.

4. What is the equation for exponential growth rate? [SS]

a) N t+1 = Nt + r Nt (1-Nt/K)

b) Nt = lt No

c) Nt = No ert

d) all of the above are exponential

e) none of the above, they represent geometric growth
  1. The spatial distribution of endangered species in the United States is
    1. different for different types of organisms
    2. similar for different types of organisms
    3. the same as species in Africa
    4. decreasing
    5. all of the above
  2. If a population grows according to the Leslie Matrix approach and the population is decreasing, then the age or size distribution of the population will
    1. be changing with the older age/size distribution increasing in frequency
    2. be changing with the older age/size distribution decreasing in frequency
    3. stable
    4. all of the above are possible
    5. none of the above

Guessing whether statements are true or false. Circle the correct answer (T for true; F for false). Complete five. (2 pts each)

  1. T F The Leslie Matrix is primarily used to test for uneven age distribution. [SS]
  2. T F Biological systems are "linear". [SS]
  3. T F Populations in which generations overlap are best modeled using an exponential (differential) equation.
  4. T F Populations in nature (not necessarily the lab) grow rapidly when small (few individuals) and level off when large.
  5. T F Populations that do not respond to food supplementation are not limited by food.
  6. T F Widespread species extinction over the past 65 million years, driven primarily by humans, has lead to there being far fewer species than before the dinosaurs went extinct.
  7. T F According the Hamilton & May model, if offspring of parents have very little chance of surviving if they disperse then the proportion of offspring dispersing should be low.
  8. T F Cheetahs are less likely to chase stotting Thomson’s gazelles compared to those not stotting and when they do chase stotters they usually fail to catch the gazelles.

Fill in the missing word or phrase. Complete five. (2 pts each)

  1. In Andrewartha and Birch's analysis of the thrips population, they determined that ________________ factors captured the overall pattern of changes in the population. [SS]
  2. Elephants communicate intraspecifically over long distances using ________________________.[SS]
  3. __________ is the study of the change in the number of individuals over time.
  4. The "seven forms of rarity" are based on these three characteristics of species: ________________, ________________, and __________________.
  5. Small populations, like the Florida panther, are likely to go extinct because of _______________ _____________ and social dysfunction, also referred to as ___________________.
  6. Three patterns of species invasions are ________________________________________, ___________________________________, and ________________________________

 

Provide short answers for the following in the space provided. Complete three. (10 pts each)

1. Mark-recapture: You wish to estimate the population of small rodents in the Arboretum. You set out traps and catch 25 and mark them and then release them. You wait a week and set traps again. This time you catch only 20 and 7 are marked. What is your estimate of the small rodent population in this area?

  

2. Given that Nt = Noert and r = 0.1, how long will it take for a population of bunnies to grow from 100 individuals to 200 individuals?

 

 

3. Describe the four easily observed characteristics of natural selection that were first described by Darwin.

 

 

4. Why do modeling in science?

  

Graphing exercises. Label axes. Complete four. (10 pts each)

1. Below, graph the spatial distribution of regularly distributed individuals in a population:

 

2. Below, graph the relationship between population density as a function of body size for animals.

 

3. Below, graph exponential and geometric growth of a population as N vs. time (do this on the same graph).

 

 

4. Analyze the graph below. [SORRY, DIDN'T EXPORT TO EXCEL]

  

5. Based on the graph above, in the space below provide a graph of N versus time. Use the three starting populations given in the above graph (marks on the N axis). Assume those are initial populations (No).

 

 

6. Provide a graph of per capita growth rate (r) as a function of N for populations growing exponentially and logistically. Do this on the same graph.

 

7. Provide a graph of the relationship between territory size and body size. On this one graph provide the relationship for both predators and herbivores.