Principles of Ecology, Guangxi University, College of Forestry
Your name in Chinese
Your name in Pinyin
Score:
1. Intro to Ecology
___________(of 13)
2. Physical Environment
___________(of 13)
3. Temperature, Water and Energy
___________(of 11)
4. Evolution
___________(of 12)
5. Behavior
___________(of 13)
6. Population Growth
___________(of 12)
7. Population Growth and Species Interactions
___________(of 11)
8. Essay on Primary Literature
___________(of 15)
TOTAL
____________ (of 100)
p. 2
Principles of Ecology 2015
Your name in Chinese ________________
Midterm 4/13/15
Your name in Pinyin_____________
(1) An introduction to ecology
I) Write a definition of ecology (one sentence; 5 points).
Ecology is the science investigating the connections (or interactions) between living organisms
and their living (biotic) and non-living (abiotic) environment.
II) What are major qualities of ecology? Write TRUE or FALSE after each sentence (8 points).
A) Ecology covers a wide range of spatial and temporal (related to time) scales. TRUE
B) Ecology covers a wide range of levels of organization, starting from the individual and
going up to the global level. TRUE
C) Ecology is an experimental science in which a hypothesis must be (is required to be)
tested in a controlled experiment. FALSE. Observational studies are also part of ecology.
D) Ecology has many applications to solving environmental problems. TRUE.
(2) The physical environment
I) In areas of the earth far from the equator there are large seasonal changes in climate. What
physical property of the earth explains this? (one to two sentences; 5 points)
The earth’s rotational axis is tilted. This results in half of the year in the northern hemisphere
being closer to the sun than the southern hemisphere, and the opposite pattern in the other
half.
II) Biomes. Name four biomes -- either terrestrial or aquatic -- that are found in China. For
each one give the name of the biome and, if they are terrestrial, where they are found in China
(for example, South, North, East, West, Central; 8 points).
Terrestrial biomes: Tropical rainforest (South), Tropical seasonal forest (South), Temperate
Deciduous forest (Central, East), Temperate Evergreen Forest (North), Boreal Forest (North),
Temperate Grassland (Northwest), Desert (West). Note: China isn’t far enough north to get
tundra. The temperate shrubland/woodland category is a rare biome not found in China (found
in Mediterranean Europe, California, South Africa and Western Australia).
Aquatic biomes include: Rocky tidal shore, sandy shores, mangroves, kelp forests, coral reefs,
open ocean; rivers, lakes, estuaries.
p. 3
Principles of Ecology 2015
Your name in Chinese ________________
Midterm 4/13/15
Your name in Pinyin_____________
3) Temperature, water and energy
I) What is an autotrophic organism? What kinds (categories) of autotrophic organisms are there
and which are most common? (define an autotrophic organism in one sentence, name two
categories, then say which category is most common; 6 points).
An autotrophic organism is able to make sugars (make carbon-carbon bonds, or organic
compunds) itself by capturing energy. If it captures energy from the sun, it’s a photoautotroph,
and if it captures energy from chemical reactions, it’s a chemoautotroph. Photoautotrophs are
more common.
II) Some heterotrophs (like bacteria) stay in the same place and eat any food that comes close
to them. Other heterotrophs (like a lion) spend a lot of energy chasing and capturing their prey.
This is an example of a “trade-off”, a subject we’ve encountered several times in class. Describe
what a “trade-off” is and why this is an example of one (2-3 sentences; 5 points).
A trade-off is the idea that organisms can have different strategies. There is no perfect strategy:
each strategies comes with its positive points and negative points. In this example, an organism
(the bacteria) that stays still doesn’t use a lot of energy. But the food it acquires is of poor
quality. In contrast, the organism that chases the food (the lion) uses a lot of energy in the
chase, but the food it captures is of good quality.
(4) Evolution.
I) Draw a line connecting the appropriate mechanism of evolution and its result (6 points).
Mechanism of evolution
Result of evolution
Natural Selection
------->
Leads to adaptations
Mutation
------->
Creates new genes
Gene Flow
-------->
Makes populations more similar to each other
Genetic drift
-------->
Can lead to loss of genetic variation in small populations.
p. 4
Principles of Ecology 2015
Your name in Chinese ________________
Midterm 4/13/15
Your name in Pinyin_____________
II) Fill in the blank by choosing one of the two choices (6 points):
Species that have a life history strategy of short lifetimes also have __many____ ( many / few)
offspring at a time and _____a little____ ( a lot / a little) investment in those offspring. They
are called __r_ (r / K) species. In contrast, __K___ (r / K) species that have long life times have
___few__ (many / few) offspring at a time, and invest ____a lot____ (a lot / a little) into each
one.
(5) Behavior
I) Make a list of the key steps in natural selection. Then make a list of the key steps in sexual
selection. (List in bullet points “1”, “2”… etc. both process; with natural selection on the left and
sexual selection on the right; 8 points).
Natural selection:
1. Individuals vary in their traits
2. This variation is heritable
3. Some individuals have traits
better fit to the environment
4. These individuals survive and
Reproduce better than others.
5. Their genes spread in the population
Sexual selection:
1. Individuals vary in their traits
2. This variation is heritable
3. Some individuals have traits
that allow them to mate better than others
4. These individuals reproduce better.
5. Their genes spread in the population.
II) Females choose male peacocks with bright tail spots. But male peacocks do not provide any
parental care. What may females obtain by selecting a good-quality male? For full credit, talk
about at least two hypotheses we mentioned in class (5 points).
You could mention three hypotheses:
1) Good genes (or the handicap principle). The well-ornamented male has good genes
which are given to the females’ offspring, both male and female. For example, the genes
might encode for immunity to disease, or ability to run well.
2) Sexy son. The female who choses the well-ornamented male has male offspring that are
themselves attractive to females, and reproduce well.
3) May be the female doesn’t obtain the any benefit, but choses because female
preference evolves jointly with the male ornamentation (“run-away sexual selection”).
(6) Population growth.
The logistic growth equation is given by the formula:
dN/dt (rate of growth) = r (N)(1- (N/K))
I)
If N is greater than K, what happens to the rate of growth (4 points)?
Growth becomes negative and the population decreases.
p. 5
Principles of Ecology 2015
Your name in Chinese ________________
II)
Midterm 4/13/15
Your name in Pinyin_____________
Make a graph of dN/dt. Make sure you label when N = K and when n = K/2 (4 points).
III) Give an example of a density-dependent mechanism that keeps a population near K (4
points). Competition (territoriality), stress, disease, toxic by-products, etc.
(7) End of population growth and start of species interactions
I) Name at least two reasons why small populations are more likely to go extinct (5 points).
Some possible answers:
1) If growth rate fluctuates (population cycles), small populations can go extinct during the
negative growth phase.
2) Small populations have low genetic variability (because of genetic drift, inbreeding).
3) The Allee effect: when population is small, individuals have hard time finding each other
to mate.
II) Competition is a ____________ species interaction (just write in the answer; 3 points)
A) + / +
B) + / C) - / III) True or false?: K species are good competitors (write TRUE or FALSE; 3 points).
True. K species are adapted to living in competitive environments. Their parents invest in them
so they can get a good start and they live long. Think of a tall tree.
p. 6
Principles of Ecology 2015
Your name in Chinese ________________
Midterm 4/13/15
Your name in Pinyin_____________
From the following three essay questions, select one and write one paragraph (~ 4 sentences)
summarizing your argument. Write your answer on page 7.
1) In the article by Kiesecker called “Synergism between trematode infection and pestide
exposure: a link to amphibian limb deformities in nature?”, please explain the major
experiment that the author conducted. What treatments were there and what were the
controls? What were the basic findings from that experiment and what did Kiesecker
conclude?
2) For the article by Gangestad and Thornhill “Menstral cycle variation in women’s
preferences for the scents of symmetrical men”, what was the basic experiment that
these researchers conducted? What was their conclusion? Do you think their conclusion
was justified (backed up by the evidence) or not?
3) For the article by Rutz and colleagues “The ecological significance of tool use in New
Caledonian crows”, look at the following figures:
Figure 1
Figure 2
p. 7
Principles of Ecology 2015
Your name in Chinese ________________
Midterm 4/13/15
Your name in Pinyin_____________
What is the basic message of the first figure? What is the basic message of the second figure? And what
is the conclusion of the article? Remember that crows use tools made out of sticks to get beetle larvae
out of cracks in the trunks of trees.
Write your essay here.
Which question did you select? (1, 2 or 3?): ________________________
Sketches of the three essays:
1) In this experiment, there were two kinds of treatments: pesticide and exposure to the
trematode worm. 6 lakes were chosen, 3 of them with pesticides and 3 without. The 3
without are the control. In all 6 lakes the researcher placed 2 types of cages with frogs.
Some of the cages had small mesh so the worms couldn’t get at them (control). The rest
of the cages had large mesh (worms can enter). The researcher found that for the large
mesh cages, the worms entered and caused frog deformities. This effect was larger in
lakes with pesticides. Therefore, he concluded that (1) trematode worms cause the
deformities, and (2) the pesticides make frogs more vulnerable to the worms, so that
their deformities are higher in the presence of pesticides.
2) In this experiment, men – who varied in their symmetry – were asked to wear T-shirts
for two nights. These T-shirts were then given to women to rate how attractive they
were. The women varied in how fertile they were (how able they were to conceive -what part of their cycle they were in or whether they were taking birth control). The
researchers showed that fertile women preferred the T-shirts of symmetrical men;
women not able to concieve or on birth control did not show such preferences. The
researchers suggest that symmetry is a signal of good genetic quality and that women
who are ready to conceive prefer men of good genetic quality. But in class we talked
about the idea that their data is not very strong (not very large samples, not very
different results).
3) In the first figure, each cross is an individual crow. We can see that most crows are
colored in red, which indicates that they eat beetle larvae. In the second figure, we see
that beetle larvae are very nutritious (include a lot of lipids = fat). So what this means is
that beetle larvae are a very important part of the diet of these crows. Since the crows
can only get the beetle larvae by using tools, the researchers conclude that tool use is
very important for the crows.