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UNIVERSITY OF EAST ANGLIA
School of Biological Sciences
Main Series UG Examination 2012-2013
COMMUNITY, ECOSYSTEM AND MACRO-ECOLOGY
BIO-2B26
Time allowed: 2 hours
Answer ALL questions in Section A, ALL PARTS of the question in Section B and
ONE question from Section C.
Write answers to EACH SECTION in a SEPARATE booklet.
The maximum number of marks available for your answers in SECTION A is 40 marks
The maximum number of marks available for your answer in SECTION B is 30 marks
The maximum number of marks available for your answer in SECTION C is 30 marks
The TOTAL number of marks available for the paper is 100
Numbers in square brackets [ ] indicate the relevant mark applied to each part of the
question.
Notes are not permitted in this examination.
Do not turn over until you are told to do so by the Invigilator.
BIO-2B26
Copyright of the University of East Anglia
Module Contact: Dr Richard Davies, BIO
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SECTION A: MULTIPLE CHOICE AND SHORT ANSWER QUESTIONS
Answer ALL questions. Unless stated otherwise all multiple choice questions have
ONE answer.
1.
The known ranges of tolerances to two environmental factors of two species
(ABCD and WXYZ, respectively) are presented in the diagram below. In the field,
however, species 1 is found only in the area ABEWFD.
Which of the following statements is true?
[2 marks]
a) The two species have the same fundamental niche
b) There is an interaction between the effects of temperature and
humidity on species 1
c) Species 1 is a weaker competitor than species 2
d) The realized niche of species 2 is WECF
e) Competition between the species is avoided
2.
Many ideas have been proposed to explain the coexistence of multiple
species with the same basic resource requirements. Identify the hypothesis that best
describes our current understanding of co-existence in territorial coral reef fish:
[2 marks]
a)
b)
c)
d)
e)
The regeneration niche hypothesis
The resource ratio hypothesis
The lottery hypothesis
The random walk hypothesis
Character displacement
Section A continues/ . . .
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.../Section A continued
3.
According to Odum’s model of successional development of an ecosystem,
which of the following propositions is true?
[2 marks]
a)
b)
c)
d)
e)
Primary succession gives way to secondary succession
Net primary production is maximal at the climax stage
Community respiration increases with successional stage
Species diversity declines with successional stage
K-selected species give way to r-selected species
4.
In which one of the following habitat types would you expect to find
halophytes growing?
[2 marks]
a)
b)
c)
d)
e)
5.
Biogeochemical cycling in an ecosystem is driven primarily by:
a)
b)
c)
d)
e)
6.
Acid heathland
Salt marsh
Shallow lake
Deciduous woodland
Tropical rain forest
Pollution
Precipitation
Succession
Catchment river flow
Energy flow
The pH of heathland soils is typically:
a)
b)
c)
d)
e)
[2 marks]
[2 marks]
<5
5-6
6-7
7-8
>8
Section A continues/ . . .
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.../Section A continued
7.
In a stream ecosystem, which of the following is not a source of
allochthonous ecosystem productivity?
a)
b)
c)
d)
e)
8.
[2 marks]
Fallen leaves from overhead branches
Organic field run-off
Aquatic plants
Wind-blown dust and soil
A submerged rabbit carcass
Terrestrial as opposed to ocean pelagic communities have:
[2 marks]
a)
b)
c)
d)
e)
A greater ratio of biomass to Net Primary Productivity
A greater ratio of nutrients to biomass
A lower level of size structuring of organisms across trophic levels
Lower rates of biomass turnover
Greater proportions of support tissue among their primary
producers
f) Relatively less energy passing through the herbivore as opposed to
detritivore system
Which one of the above options completes an incorrect statement?
9.
If gross primary productivity = GPP, net primary productivity = NPP, net
eocosystem productivity = NEP, autotrophic respiration = RA, and heterotrophic
respiration = RH, then which of the following is true:
[2 marks]
a)
b)
c)
d)
e)
NPP = GPP + RA
NPP = GPP – RA – RH
NEP = NPP + RA
NEP = GPP – RA – RH
NEP = GPP – NPP
10.
Compared with unsaturated insect communities, saturated insect
communities:
[2 marks]
a) Are likely to show community structure that is less influenced by
competition
b) Are closer to equilibrium
c) Have a greater proportion of empty niches
d) Have species richnesses that are more influenced by the richness
of their regional species pools
e) Are more common
Section A continues/ . . .
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.../Section A continued
11.
Certain regions may be considered “museums” of biological diversity because
they have:
[2 marks]
a)
b)
c)
d)
e)
Low extinction rates
Unstable climate
High rates of DNA evolution
High net primary productivity
Many endemic species
12.
A “collection of species that consume the same class of environmental
resources in similar ways” defines:
[2 marks]
a)
b)
c)
d)
e)
Taxocene
Assemblage
Cohort
Guild
Food web compartment
13.
The combined effects of climate change and habitat loss on biodiversity are
predicted to be synergistic. In this context, does “synergistic” mean:
[2 marks]
a) The effects of climate change and habitat will be additive
b) The effects of climate change and habitat loss will result in
evolutionary changes in species
c) The effects of climate change and habitat loss will result in
disaggregation of species associations
d) The effects of climate change and habitat loss will result in nonrandom extinctions
e) The effects of climate change and habitat loss will be greater than
the sum of their individual effects
14.
Which one of the following species’ traits is not typically associated with
greater extinction risk?
[2 marks]
a)
b)
c)
d)
e)
Large body size
Wide niche breadth
Narrow distributional range
High trophic level
Long generation time
Section A continues/ . . .
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.../Section A continued
15.
Using a full factorial sampling design and assuming a minimum spatially
independent level of replication of five sites sampled per combination of treatments,
how many sites would you have to sample to tease apart the multiple effects of
surface fires (two burn treatments: burnt and unburnt), soil types (two soil types: clay
and sandy), fertilizer input (two treatments: low and high), and season (four seasons:
early-dry, late-dry, early-wet and late-wet seasons) on the plant diversity of a
grassland community?
[2 marks]
a)
b)
c)
d)
e)
16.
20
40
80
160
320
Resource partitioning would be most likely to occur between:
[2 marks]
a) Sympatric populations of a predator and its prey
b) Sympatric populations of species with similar ecological niches
c) Sympatric populations of a flowering plant and its specialized insect
pollinator
d) Allopatric populations of the same animal species
e) Allopatric populations of species with similar ecological niches
17.
Elephants are not the most common species in African grasslands. The
grasslands contain scattered woody plants, but they are kept in check by the
uprooting activities of the elephants. Take away the elephants, and the grasslands
convert to forests or to shrublands. The newly growing forests support fewer species
than the previous grasslands. Elephants can be defined as what type of species in
this grassland community?
[2 marks]
a)
b)
c)
d)
e)
Redundant
Dominant
Keystone
Dominant and keystone
None of the above
Section A continues/ . . .
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.../Section A continued
18.
Two barnacle species, Balanus and Chthamalus , can both survive on the
lower rocks just above the low-tide line on the Scottish coast, but only Balanus
actually does so, with Chthamalus adopting a higher zone. Considering the
fundamental and realized niches of these species, which of the following best
accounts for this habitat separation?
[2 marks]
a)
b)
c)
d)
e)
Competitive exclusion
Predation of Chthamalus by Balanus
Cooperative displacement
Primary succession
Mutualism
19.
Consider the three alternatives 1 to 3 (below) to complete the statement
“Introduced or exotic species…”
[2 marks]
1) Often fail to colonize the new area
2) May become common enough to become pests
3) Can disrupt the balance of the natural species with which they
become associated
Which of the following is true?
a)
b)
c)
d)
e)
Only option 1 completes a correct statement
Only option 2 completes a correct statement
Only option 3 completes a correct statement
Both options 2 and 3 complete correct statements
1, 2 and 3 all complete correct statements
Section A continues/ . . .
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.../Section A continued
20.
On the basis of the figure below, which of the following sentences can be
interpreted as correct for oceanic islands that are isolated from the mainland:
[2 marks]
a) The extinction rate is higher in islands because their island habitats
are smaller than those in the mainland;
b) The extinction rate is lower in the mainland because there are more
species there to begin with;
c) The extinction rate is higher in islands because there is little or no
rescue effect from the mainland;
d) The species richness is higher in the mainland because mainland
species are intrinsically less prone to extinction;
e) The species richness is lower in islands because mainland species
require larger areas.
END OF SECTION A
Section B begins on next page
BIO-2B26
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SECTION B:
Answer ALL PARTS of this question
21.
A macro-ecologist is investigating the environmental determinants of the
distribution of species richness of amphibians across the Oriental region. S/he has
sampled the presence/absence of each species to a 400-km x 400-km equal-area
grid (i.e. where grid cells sample the same amount of area) and calculated species
richness as the sum of all species presences within each grid cell. For each grid cell,
there are data for each of five environmental predictors of interest including: Net
primary productivity (NPP); mean annual temperature; number of habitat types;
elevational range (maximum minus minimum elevation); and annual precipitation.
The ecologist intends to use ordinary least squares (OLS) regression to carry out the
analysis.
(a)
At the sampling resolution of this study (400-km x 400-km), does total
amphibian species richness within a grid cell represent a measure of alpha-, beta- or
gamma-diversity? Explain the reasons behind your answer.
[5 marks]
Figure 1. Histogram of (A) amphibian species richness, and (B) square-roottransformed amphibian species richness. Estimated normal curves are fitted
by PASW (or SPSS). Results of Kolmogorov-Smirnov normality tests are
presented within each histogram.
(b)
The ecologist looked at histograms of the amphibian richness data (A) and
square-root-transformed amphibian richness (B), and performed a normality test of
each (Kolmogorov-Smirnov test) before doing any linear regression analysis. Based
on the results of these tests, explain whether the ecologist should perform the
regression analysis on A (amphibian species richness) or B (square-roottransformed amphibian species richness) and why?
[5 marks]
Section B Q21 continues/ . . .
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.../Section B Q21 continued
(c)
First the ecologist carried out simple linear regressions (single-predictor
models) of each of the candidate predictors on its own (see Table 1A). Based on the
single-predictor models (Table 1A), which is the most important predictor, and which
is the least important, in explaining amphibian species richness, and why? [5 marks]
A
Predictor
Number of habitat types
NPP
Temperature
Elevation range
Precipitation
Single-predictor models
B (slope)
P-value
Adjusted-R2
0.084
0.002
0.164
7.862
<0.0001
0.424
-0.152
0.034
0.123
3.041
<0.0001
0.328
5.223
<0.0001
0.358
B
Predictor
Number of habitat types
NPP
Temperature
Elevation range
Precipitation
Multi-predictor full model
B (slope)
P-value
Overall Adjusted-R2
0.079
0.001
6.111
0.002
0.531
0.075
0.265
1.753
0.105
<0.0001
0.941
C
Multi-predictor MAM model
Predictor
B (slope)
P-value
Overall Adjusted-R2
Number of habitat types
0.065
0.001
NPP
6.331
<0.0001
0.534
Temperature
removed
Elevation range
1.753
<0.0001
Precipitation
removed
Table 1
B (slope) is the regression coefficient for each predictor,
P-value is the significance of that slope, and
Adjusted-R2 is the proportion of total variation explained.
Section B Q21 continues/ . . .
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.../Section B Q21 continued
Next the ecologist wishes to construct a minimum adequate model (MAM), in other
words to determine the minimum set of predictors needed to explain the maximum
variation in amphibian species richness. The first step in achieving this is to carry out
a multiple linear regression using all the candidate predictors together in a ‘full
model’ (see Table 1B).
(d)
Looking at the full model results in Table 1B, you will notice that two of the
predictors have become non-significant, in contrast to their single-predictor models
(Table 1A). Give a statistical explanation for why this might be happening.
Additionally, give a spatial ecological reason?
[5 marks]
In order to find the minimum adequate model (MAM), the ecologist performs a stepdown procedure in which predictors are removed in ascending order of their
importance in the model until only significant predictors remain in the final MAM (see
Table 1C).
(e)
Looking at the results in Table 1C, what is the percentage of variation in
amphibian species richness that is explained by the MAM? Describe the main
ecological relationships (including their directions of slope) explaining amphibian
species richness that are highlighted by the MAM results.
[5 marks]
(f)
Describe one plausible underlying mechanism to explain the influence of each
of (i) NPP, and (ii) Elevation range, on the distribution of amphibian species richness.
[5 marks]
END OF SECTION B
Section C begins on next page
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SECTION C: ESSAY QUESTION
Answer ONE question
[30 marks]
22.
How do biogeochemicals cycle in ecosystems? Using examples, discuss the
significance of such cycles, locally and globally.
23.
In the context of food web ecology, discuss the importance of indirect effects
and their role in structuring ecological communities, giving examples of their
relevance to conservation and natural resource management.
24.
With examples from both terrestrial and marine systems, critically outline Joe
Connell’s (1978) ‘Intermediate Disturbance Hypothesis’ ,including its theoretical
basis, major predictions and assumptions, and how this hypothesis can help us
understand the species diversity of ecological communities under more severe
and/or more frequent natural or anthropogenic disturbance regimes.
END OF PAPER
BIO-2B26
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BIO-2B26 EXAMINATION MARKERS 2012-13
[Do not print this when printing to take to Examinations Office! This is for our
information only.]
Question No.
Section A
Section B Q21
Section C Q22
Section C Q23
Section C Q24
BIO-2B26
1st Marker
Prof T Davy
Dr R Davies
Prof T Davy
Dr R Davies
Prof C Peres
2nd Marker
Dr R Davies
Prof T Davy
Prof C Peres
Prof T Davy
Dr R Davies
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