Some possible questions for the Ecology Final Exam-Fall 2005

1.      When a predator is faced with a variety of choices of prey items, optimal foraging theory predicts which of the following?  (Recall the optimal foraging game.)  The predator should

A.  select the most profitable item, the one that gives the greatest net energy gain.

B.   feed more selectively when profitable food items are abundant.

C.   include less profitable items in the diet when the most profitable items are scarce.

D.  ignore unprofitable food items, however common, when profitable prey are abundant.

E.   do all of the above.

2.      The transfer of heat between two touching solid bodies with different temperatures is

A.  evaporation.

B.   radiation.

C.   conduction.

D.  convection.

E.   insulation.

3.      Which of the following is/are true?

A.  the smallest animals are all poikilothermic

B.   larger poikilotherms are restricted to areas of more stable climates

C.   with rare exceptions, fish and plants are poikilothermic

D.  there are very few endotherms weighing less than 5 g.

E.   all of the above are true

4.      A eutrophic lake

A.  is high in nitrogen and phosphorus.

B.   is low in nutrients.

C.   has no phytoplankton.

D.  has few fish.

E.   all of the above.

5.      An organism with wide tolerances to heat is

A.  eurythermal

B.   stenothermal.

C.   poikilothermic.

D.  homeothermic.

E.   euryhaline.

6.      The biological community that characterizes the tundra

A.  is dominated by large trees.

B.   is dominated by mosses, lichens, and small trees which grow in sheltered areas.

C.   is characterized by a diverse reptile and amphibian fauna.

D.  is characterized by migrating herds of herbivores, small mammals, and predatory birds.

E.   b) and d) only.

7.      A biological community's productivity is a measure of

A.  its number of species.

B.   the number of individuals in the community.

C.   available solar energy that can be converted to biomass.

D.  the amount of biomass produced in the community.

8.      The thermocline is the layer in a lake at which

A.  pollutants are trapped and held.

B.   seasonal lake mixing occurs.

C.   the warm upper zone meets the cold lower zone.

D.  nutrient levels are the lowest.

9.      Some researchers think that large predators often have little effect on the population size of their large prey (e.g. the Dall sheep-wolf system). Small predators are often methodical killers, conquering their prey easily (e.g. ladybugs and aphids).
a. Why do large predators have little effect?
b. Why are small ones more likely to eliminate a prey population?
c. It seems to me that all predators should pick on small or defenseless prey.  But, tigers do indeed sometimes attack healthy, large adult prey items, so taking the risk must be worthwhile at least sometimes.  Why doesn't this big feline act like his nice American pussycat cousins and feed on safe, defenseless mice?

10.     Only two decades ago demographers were predicting that world population would soon reach intolerable levels.  They were looking at graphs like this one:








They wondered where we'd put all the people.  Applying your knowledge of population growth of animals to humans, answer the following:
a. do you see any inadequacies of the arguments of those who say humans will continue to increase exponentially?
b. for prehistoric man, 'K' values were quite low compared to now. How has man increased the 'K'?.  Be sure to tell what 'K' is!
c. does man have any competitors which act as influences to curb his intrinsic rate of increase?
d. what implications are there to humankind if populations did continue to increase exponentially?  If population levels off at the top of a sigmoid curve?

11. Suppose you have photoidentified 30 humpback whales around the island of Oahu in one cruise around the island.  Two weeks later you return to the same area and photograph all the whales you encounter.  On the second trip you photograph a total of 50 whales, of which 10 were photographed previously.  Use the Lincoln-Peterson index to estimate the number of humpback whales around Oahu during your study. (10 pts)

12.     The Hawaiian Islands are an archipelago pretty well isolated from any major land masses.  They have their own well-developed endemic flora and fauna. 
a. Since these islands are volcanic in origin, how and from where might this biota have come to exist here?  (Note:  there is more than one possible answer.  Propose several hypotheses.)
b. Why is there such a high incidence of endemism?
c. Many of these endemics are officially listed as endangered or threatened.  What factor(s) contribute to this problem?
d. What is (are) the source(s) of species that are filling the empty niches left by these disappearing creatures?

13.     Since the opening of the Welland Canal in 1829, all of the species of fish in the Atlantic have presumably had access to the Great Lakes.  However, only a few have established themselves, and only a handful seem to have had a major impact on the ecosystem.  These include the alewife, sea lamprey, white perch and smelt.
a. Why have so few of these Atlantic species taken up residence in the
Great Lakes?
b. Why have even fewer yet had a major impact?
c. What factors are important in determining whether a new species will fit into these systems?

14.     In order to avoid fighting for territories, mates, food, etc., many animals have evolved aggressive but non-physical methods of avoiding conflict. (20 pts)
a. What is the advantage of avoiding all-out battle?
b. Occasional physical contests are sometimes observed, however.  What kind of animals would you expect to find engaged in the conflict?
c. What kinds of tactics do animals use to avoid the battle?  You must describe at least three specific examples and tell how they work.

15.     Species A and Species B are unable to coexist in culture, Species A always winning out.  However, if A and B are put into a new culture with another organism, Species C, all three survive.  A study of the system shows that C preys on both A and B.  How does the addition of another component to this system allow all to coexist?  If you can think of several hypotheses, discuss them all.

16.     Hunting is an emotional issue with ecological implications.  Hunters often use population ecology principles to support their positions.  A typical stand is "Hunting and trapping are valuable to the health of wildlife populations.  If it weren't for hunters, they would overpopulate and many animals would starve."  Using your knowledge of mortality, predation, growth, and interspecific competition, discuss the PRO's and CON's of hunting.  Use only facts--no sentimentality (also known as the Bambi Syndrome) or National Rifle Association propaganda will be allowed!  Conclude with a statement explaining why you, as an ecologist, are either in favor of hunting, opposed to it, or have indifferent or mixed feelings about it. (20)

17.     What grade (0-100%) would you give yourself for participation in the second half of the course?  Justify your answer if you wish.

18.     In some lions, infanticide is occasionally observed.  Why should females allow males to kill their cubs?  Be sure to explain in terms of costs and benefits.

19.     Males and females usually have different priorities and strategies in trying to maximize their fitness.  What is their overall goal?  Why might they try to achieve it in different ways?

20.     Conflict between parent and offspring is natural.  Explain, with examples, why sooner or later it's to everyone's benefit (mom, dad, & kid) that the young ones be forced out of the family.

21.     Some organisms do not play by the "rules" of the system.  Explain when it might be worthwhile for you to be a cheat or a sneak.  When would it NOT be worthwhile? (10)

22.     Under what kinds of conditions would you expect to see the following mating systems develop?
a) monogamy
b) polygyny
c) polyandry
d) leks
e) cooperative breeding
f) hermaphroditism

23.     A biologist once said, "I would give my life for three brothers or nine cousins."  What did he mean?

25.     The entire discussion we have had in this class is based on the concept that EVERY organism's role in life is to successfully raise kids--that is, to optimize its own fitness.  Do you really believe that this truly is the goal of all organisms?  It becomes awkward, difficult, and humbling to figure out how humans fit into this picture.  Do you feel that we play by the same rules as all other creatures?  Be sure to discuss any points which you feel do NOT apply to humans.

26.     We are a sexually obligate species.  Some organisms are able to switch back and forth between sexual and asexual reproduction.  What are the disadvantages and advantages of each?  Why do you suppose that our species must be sexual and doesn't have the ability to be AC/DC? (20)

27.     Which of the following statements is/are true?

A.  Competition occurs when the niches of two coexisting species are similar.

B.   Competition between two species for a resource can result in the exclusion of one of those species.

C.   If niche overlap between two species is reduced, the two species can coexist.

D.  All of the above are true.

E.   None of the above is true.

28.     All of the following are characteristic of the temperate deciduous forest except

A.  precipitation ranges from 75-125 cm (30-50 in) per year.

B.   soils consist of a topsoil rich in organic material and an underlying clay layer.

C.   broad-leafed hardwood trees are rare.

D.  they were among the first biomes to be converted to agricultural use and many remain seriously altered by human activity.

29.     Natural selection gradually makes a species

A.  more intelligent.

B.   physically bigger.

C.   more adapted to its environment.

D.  more aggressive.

30.     Primary production varies worldwide.  Some ecosystems have consistently higher production than others.  Cite one example each of a system with very high and very low productivity.  Discuss reasons for these differences.  Why is this ecosystem so productive?  Where would you expect to find the most productive ecosystem in Pennsylvania?  (Be specific--not necessarily to geographic location, but to TYPE of ecosystem.)  Why is this ecosystem so productive?

31.     The reason that we do not have one "superplant" which has dominated the world and out-competed every other type of plant is that NO plant can be best suited for every climatic situation.  Water loss and photosynthesis are intimately linked.  Describe the three strategies (pathways) of photosynthesis which have evolved and allow plants to thrive in the driest or the wettest areas on earth.  Do aquatic plants have the same problems of photosynthesis and water loss?  How are they modified to be photosynthetically successful in their environment?