BIO360 Exam 1 Key
(Questions are identical in Code 16, but in a different order)

Multiple Choice Questions (2 pts each)

1. A cost of sex is:
A. evolutionary cost of meiosis
B. maintenance of gonads
C. the need for mating behaviors
D. All of the above

2. In the same lake, different individuals of the same species of aquatic snail can reproduce sexually or asexually.  A leading explanation for the existence of the two forms is that:
A. Different physical environments in the lake at different depths favor different forms
B. The two forms provide variability to deal with changing physical environments from year to year
C. The sexual form is found where the incidence of disease is high
D. There is progressive evolution to the higher, sexual form

3. In a recent study by an NCSU professor, Dr. Nadia Singh found that sexually-reproducing fruit flies infected by wasps had _______ rates of genetic change through recombination.
A. higher
B. lower
C. about the same
D. None of the above

4. In an experiment with flour beetles, it was found that sexual selection __________ extinction risk.
A. increases
B. decreases
C. does not change
D. has variable effect on

5. Individual monarchs in fall migration from North America to Mexico:
A. have never made that migration before
B. have made the migration once before
C. have made the migration several times before

6. For which of the following organisms does capsaicin, the active ingredient in hot chilies, have NO effect in reducing consumption?
A. Curve-billed Thrasher
B. Packrat
C. Cactus mouse
D. Fusarium, a fungal pathogen

7. In Bolivia, the same species of chili can vary from intensely hot to not hot at all (high to low capsaicin).  The pattern of higher “heat” in chilies was directly related to the abundance of what species?
A. Curve-billed Thrasher
B. Packrat
C. Cactus mouse
D. Acroleucus coxalis, a seed bug

8. Which social interaction benefits the recipient (and not the initiator) of an interaction?
A. Selfishness
B. Altruism
C. Cooperation
D. Spitefulness
E. All of the above

9. In South Pacific reefs, the number of parasites of five fish species living at higher densities in unfished reefs was:
A. lower
B. the same
C. higher
D. None of the Above

10. For social white-fronted bee-eater birds, their probability of helping individuals that are not their own direct offspring at a nest is highest when the coefficient of relationship is:
A. 0
B. 0.1
C. 0.25
D. 0.4
E. 0.5

11. In Eusocial Insects such as bees:
A. adults live separately
B. each generation occurs distinctly, with periods between
C. there is cooperation in nest building and care of eggs and larvae
D. many different queens reproduce simultaneously in the same hive or colony

12. How do Monarch butterflies find their way from Canada to Central Mexico each fall?
A. Time-compensated sun compass
B. Memory, returning to where they were born
C. Magnetic compass orientation
D. All of the above

13. In the absence of natural selection, genetic drift will cause alleles to become fixed most rapidly in the population(s) of which size?
A. 4
B. 40
C. 400
D. 4000
E. All of the above

14. Smaller populations have lower genetic variation because of:
A. demographic bottlenecks
B. lower rates of drift relative to natural selection
C. lower natural selection
D. lower change that close relatives will mate

15. Effective population size (Ne) is almost always lower than actual population size (N) because, for example:
A. sex ratios are equal
B. family sizes vary, with some parents contributing more offspring
C. breeding systems are typically monogamous
D. environmental conditions are constant

16. In population ecology, scientists track the rate of change in populations by measuring additions to the population such as ________ and subtractions from the population such as _____________.
A. immigration, birth
B. emigration, death
C. death, birth
D. immigration, death
E. emigration, immigration

17. In a study of a butterfly, tiger swallowtail, at Umstead Park, every single individual is counted.  This is an example of:
A. density computed as the number per area, then extrapolated to the entire area
B. a census
C. a mark-recapture study
D. none of the above

18. Last summer, Dr. Haddad caught and marked 40 St. Francis’ satyr butterflies.  The next day, he captured 40 more butterflies, of which 20 were marked.  The size of this butterfly population was:
A. 40
B. 60
C. 80
D. 100

19. Which of the following equations is used to project population size through time, under conditions of unlimited, geometric growth?
A.  N(t) = N(0)ert      
B.  N(t) = N(0)t
C.  dN/dt = rN
D.   = er
E.  r = b - d

20. If you measure the size of a chickadee population in three consecutive years, and its population size in year 1 is 1214, in year 2 is 1214, and year 3 is 1214, what is its geometric rate of increase?
A. 0
B. 0.15
C. 1.0
D. 1.50
E. 150

21. In a life table, the first value in the survivorship column (labeled lx) is 1.000 because:
A. All newborn individuals are, by definition, alive at age 0.
B. All individuals are, by definition, alive at age 1.
C. The individuals tracked by a life table are, by definition, immortal.
D. This is the point in the life table where fecundity is greatest.

22. Life tables revealed that conservation was important for which stage of the life history of loggerhead sea turtles?
A. Eggs
B. Hatchlings on their way from nests to the sea
C. Subadults

23. When a population grows according to the density-dependent (logistic) model, what is the value of r when the population is stable?
A.  r = r0
B.  r = 0
C.  r = K
D.  r = N

24. Which of the lines in the graph to the right is characteristic of exponential (that is, density-independent) population growth?
B.  r does not change with respect to population size (size increases or decreases)

25. When a population grows according to a logistic (density-dependent) model, what happens if the population exceeds carrying capacity?
A.  The population resumes exponential growth.
B.  The size of the population remains constant.
C.  The population goes extinct.
D.  The size of the population begins to decline.

26. The fertility rate of sub-Saharan Africa is:
A. 1.0
B. 2.0
C. 2.1
D. 2.51
E. 5.1

27. The human fertility rate is reduced when
A. wealth increases
B. education increases
C. contraceptive use increases
D. rates of disease decrease
E. All of the above

28. Why do lemmings commit mass suicide by jumping into the ocean?
A.  Lemming population densities become too high
B.  It is a response to disease epidemics
C.  This represents a mistaken attempt at dispersal
D.  Lemmings do not do this

29. Which of the following fisheries for whales had collapsed by the time of the 1986 whaling moratorium?
A. Blue whales
B. Fin whales
C. Sperm whales
D. Sei whales
E. All of the above

30. Which concept describes how incentives that favor high resource extraction (fishing harvests) by individuals can lead to a sum total of extraction that is unsustainable?
A. Maximum sustainable yield
B. Carrying capacity
C. Quotas
D. Tragedy of the commons


Short Answer or Short Essay Questions

31a.  (3 pts) What is the difference between a “Founder effect” and a “Population bottleneck”?
A founder effect refers to a small number of individuals that establish a new population with a subset of alleles.  A population bottleneck refers to random loss of alleles that accompanies reduction in population size.

31b.  (3 pts) How can population bottlenecks reduce genetic diversity?
By random processes, some alleles can be lost by chance when population size is reduced dramatically. Note that this is random, not selected.

32. (4 pts) List four causes of extinction.
a.  natural causes
b. habitat loss
c. invasive species
d.  overhunting
- climate change

33a. (4pts) How does a species’ abundance relate to its likelihood of extinction? What is the extinction vortex?
At low abundance, populations are reduced by genetic drift, inbreeding, bottlenecks, and environmental catastrophe. The extinction vortex refers to the negative reinforcement of these factors.

33b. (2 pts) Can super-abundant species go extinct?  Justify your answer with an example.
Yes, super-abundant species can go extinct.  As with the Passenger Pigeon.

34.  (3 pts) What is the difference between the per capita growth rate and the total population growth rate?
The per capita growth rate, r, is the number of offspring produced each year by every individual (on average). The total population growth rate dN/dt is the change in total population size per unit time.

35.  (3 pts) Calculate the per capita growth rate for a butterfly population with these characteristics, and assuming density-independent population growth:
You must show your work for full credit.
Population size (N) = 100
Carrying capacity = 2000
Birth rate = 0.18
Death rate = 0.06

r = b-d = 0.18-0.06 = 0.12

36. You are interested in determining the population growth rate for a population of brook trout that has different ages.  Brook trout live until they are 3 years old and start reproducing when they are 2 years old.  They have 20 offspring when they are 2 years old and 30 offspring when they are 3 years old.
Age    #dying  #surviving     lx    bx      lxbx           xlxbx      
0 years    40        100              1.0    0          0                0
1 years    40        60                 0.6   0           0                0
2 years    10        20                 0.2    20          4                8
3 years    10        10                 0.1    30           3               9

a. (4 pts) Complete the columns for “Number surviving”, lx, and bx.

b. (3 pts) Compute the net reproductive rate, R0.  sum of column lxbx = 7.0

c. (3 pts) Calculate the mean generation time (T).  Leave your answer as a fraction.   T = sum of column xlxbx/R0 = 17/7.0

d. (4 pts) Is this population growing or shrinking?  How do you know?  Growing.  When R0 > 1, each female is more than replacing herself

37. (4 pts) Draw the birth rate and death rate over time in the demographic transition. Label lines for birth rate and death rate. Label the location of four stages of the transition on your graph.
Stage 1: birth and death rates are nearly equal and high
Stage 2: death rates decline, birth rates stay high
Stage 3: birth rates decline and death rates are low
Stage 4: birth and death rates are nearly equal and low