Ecological Principles
ENVL 2200
Spring 2012
NAME__________________________________
Exam 2
ANSWER ONLY IN THE SPACE PROVIDED, NOT ON THE BACK
1. (5) Define, with examples, population, population density, ecological population density, dispersal and
dispersion.
Population
Population density
Ecological population density
Dispersal
Dispersion
2. (4) What factors are likely to limit northern elephant seal population growth? Describe the role of
dispersal in its life cycle and population dynamics. OR What are sources and sinks for populations? Why is
it not necessarily a good idea to save the largest population (in area or numbers) if you can’t save all
populations of a species?
3. (3) Define carrying capacity. What is the name of one model of population growth that includes
carrying capacity? What assumptions does this model make about the population?
4. (6) List three factors that help prevent predators from wiping out their prey populations in nature.
BONUS (1) how does lack of these help explain why Gause’s Paramecium were wiped out by Didinium?
1.
2.
3.
ANSWER ONLY IN THE SPACE PROVIDED!
Ecological Principles
ENVL 2200
Spring 2012
NAME__________________________________
Exam 2
5. (4) Define and give examples of density-dependent and density-independent factors
OR
density-legislative and density-governing factors
6. (3) Comparing the rate of increase of insects like lice and rice weevils, which contributes more to a high
value of r, high net replacement (R0) or short generation time (T)? Why are insect rates of increase affected
by temperature changes?
Higher r (circle one):
high R0
short T
Effect of temperature change explanation:
7. (6) Define census and give examples of absolute and relative methods of sampling populations
Census definition:
Absolute method example:
Relative method example:
8. (4) If you were to make a graph of a predator’s numerical response to a particular prey species, what
would the label on the y-axis be? What about the x-axis?
9. (4) Define and give an example of an endemic species and a disjunct distribution
OR
Sketch the age structure for a fast growing population of rabbits
10. Circle the correct answer (3) If the population density of the prey in this graph is at point “A” which
way will it move, left or right?
LEFT
RIGHT
(3) If the population density of the prey in this graph is at point “B” which way will it move, left or right?
LEFT
RIGHT
ANSWER ONLY IN THE SPACE PROVIDED!
Ecological Principles
ENVL 2200
Spring 2012
NAME__________________________________
Exam 2
11. (4) How do populations grow in an unlimited environment? Give an example of an actual population
other than humans that has shown this kind of growth for over 10 years.
They grow_____________________
Example______________________________________
12.(6) Answer one (1): What genus of trees dominates early in old field succession in the Pine Barrens?
What genus dominates later, if fires don’t intervene? Why? OR Why are “large tree form” oaks missing
from areas of the Pine Barrens that experience killing fires more often than about once per 20 years?
13. (5) How did introduction of snowshoe hares and extinction of timber wolves affect the balance among
predators and prey on Newfoundland? Which populations were cycling when Bergerud published his
study? What seemed to cause the populations to cycle?
14. (5+5) Ask and answer (in this space) a good, challenging discussion question on material covered
AFTER the first exam, and which is not already on this exam, including the bonus questions!
ANSWER ONLY IN THE SPACE PROVIDED!
Ecological Principles
ENVL 2200
Spring 2012
NAME__________________________________
Exam 2
LIFE TABLE
Complete the life table for the following population
age (x)
0
1
2
3
4
5
# found dead
120
50
20
110
200
0
500
# alive
500
380
330
310
200
0
lx (1)
1.00
0.76
0.66
0.62
0.40
0.00
mx
0
0
1
3
0.1
0
R0=
T=
r~
lxmx
0.00
0.00
0.66
1.86
0.04
0.00
2.56
2.76
0.34
lxmxx
0
0
1.32
5.58
0.16
0
7.06
(5) What is l0 for this population?
(10) Compute and fill in the values of l x for the data given above.
(10) Calculate R0 from the data. CIRCLE the status of this population
STABLE
INCREASING
DECLINING
4. (5) How large will the population be after four generations, if it starts with 100 individuals?
BONUS
(3) Compute T for the population above.
(2) Compute an approximate value of r for this population.
(4) Define and give examples of
contest competition
territory
mutualism
K-selected species
ANSWER ONLY IN THE SPACE PROVIDED!