Biology 321, Ecology Dr. Chris Paradise, Davidson College

 

BIOL 430 (Ecology course from another college), Exam 2                                                 10/27/99

In each section, use only the space provided.  This exam is worth 125 points, 1/8 of your class grade.  You have 50 minutes.  Allocate your time wisely.

A.            Multiple choice.  Choose by circling the most correct answer for each question, unless otherwise specified.  10 questions, 4 points each = 40 points.

1.      Which of the following best describes the fundamental niche of an organism?

  1. All the biotic factors that determine where a species can live.
  2. It is smaller than the realized niche.
  3. All the abiotic factors that determine where a species can live.
  4. It is determined by transplant experiments.

2.      Stochastic models of population growth

  1. assume a constant environment, just like the exponential growth model.
  2. are based on probabilities and variation in individuals and extrinsic factors.
  3. are much the same in form as age-structured population growth models.
  4. do not take into account the fact that individuals in a population differ.

3.      Which of the following statements best represents the relationship between the HSS hypothesis and competition?

  1. There is no relationship between the two.
  2. Herbivores are food-limited and consequently compete for food.
  3. The prediction that any trophic level is food-limited implies that species within that trophic level compete for food.
  4. Both b and c are equally correct.

4.      Treehole mosquitoes (Aedes triseriatus) may be affected by which of the following factors?

  1. Competition with the rat-tailed maggots.
  2. Presence of leaf-shredding beetle larvae.
  3. Amount of leaf litter present in the habitat.
  4. Amount of water present in the habitat.
  5. All of the above.
  6. b, c, and d only.

5.      Why is salt regulation difficult for marine iguanas and sea snakes?

  1. They have a higher internal concentrations of sodium than sea water, so they tend to lose sodium.
  2. They are constantly taking up excess sodium through their gills.
  3. They drink sea water and eat salty food, and their kidneys cannot produce urine more concentrated in sodium than their internal body sodium concentration.
  4. They drink sea water and eat salty food, and their kidneys produce urine much more concentrated in sodium than their internal body sodium concentration, but at a high energetic cost.

6.      Which of the following biotic interactions could be symbiotic?

  1. Mutualism
  2. Predation
  3. Parasitism
  4. All of the above.

7.      The physiological basis for the evolution of bacteria that inhabit the extreme environments of hot springs may be

  1. the evolution of enzymes that function at all temperatures.
  2. the interaction between temperature and biotic interactions of bacteria with their mutualists.
  3. Bacteria do not live in hot springs; the statement above is flawed.
  4. the evolution of proteins and enzymes that have optimal function at the high temperatures seen in that environment.

8.      The results of replacement series experiments with two species of wild oats performed by Marshall and Jain (1969) reveal that

  1. interspecific competition was not apparent between these two species.
  2. interspecific competition was apparent for each of these two species at every density tested.
  3. intraspecific competition was not demonstrated for either of these two species.
  4. interspecific competition affected both species only at higher densities.

9.      Which of the following are mechanisms of competition (circle all that apply)?

  1. Exploitative
  2. Mullerian mimicry
  3. Facilitation
  4. Overgrowth
  5. Preemptive
  6. Migration

10.  Which of the following is true?

  1. A survivorship curve that shows large mortality occurring in early ages of individuals is indicative of a K-selected population.
  2. Human populations generally exhibit survivorship curves with a linear rate of loss (Type II survivorship).
  3. The carrying capacity in the logistic growth model is assumed to be constant for a particular population in a particular environment.
  4. Size of animals is positively correlated with the instantaneous population growth rate.

B.         Short Answer: Use only the space provided below each question to answer (15 pts each = 45 pts).

1.      Briefly describe a type of mutualistic interaction and either how it may be viewed as reciprocal parasitism or the costs and benefits to each of the participants.

2.      An aquatic ecologist observes that two species of freshwater mussel (cousins of clams) have disjunct distributions and are never found together.  One species, the pink mussel, is only found in large streams, while the blue mussel is found in smaller tributaries of these large streams.  Develop one testable hypothesis to explain this pattern, and design a field experiment to test that hypothesis.

3.      Choose either plants or animals, and discuss in detail how light may be an important factor for the overall ecology of that organism.

C.        Outline of an essay (40 points). Use the space on the back to answer.  Do not write an essay; simply make an outline.  The essay will come later, as your second writing assignment.

Select one of the biotic interactions that we have discussed.  Outline the following four phenomena for that interaction: 1) how this interaction could be a selective agent in the evolution of both of the participants, 2) how an abiotic factor might interact with this interaction, 3) how another biotic interactions could affect the chosen one, and 4) how this interaction could alter the number or types of species in a community.  Be sure to use examples for each of the phenomena (real or hypothetical).

 

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