I' What is Ecology

1
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

2
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

- the nature of the interaction Lots of
species can tolerate the same abiotic conditions.
If they "do well" under these conditions, they
will convert resources to offspring
efficiently... and their populations will
increase. At some point, as the individuals
continue to reproduce, they will compete with
themselves (intraspecific competition) and with
other populations (interspecific competition).
3
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

- the nature of the interaction Lots of
species can tolerate the same abiotic conditions.
If they "do well" under these conditions, they
will convert resources to offspring
efficiently... and their populations will
increase. At some point, as the individuals
continue to reproduce, they will compete with
themselves (intraspecific competition) and with
other populations (interspecific competition). -
each organism will get less of the resource, or
they will have to invest MORE energy in getting
the same amount of resource. In either case, all
competing organisms have a LOWER ENERGY PROFIT in
the presence of competitors... competition
affects BOTH organisms/species negatively.
4
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

- the nature of the interaction - the
selective pressures Selection will favor
organisms that REDUCE the frequency and intensity
of the competitive interaction. They can do this
"resource partitioning"
5
Selection will favor organisms that REDUCE the
frequency and intensity of the competitive
interaction. They can do this "resource
partitioning"

resource axis
6
Selection will favor organisms that REDUCE the
frequency and intensity of the competitive
interaction. They can do this "resource
partitioning"

resource axis
remember, selection is differential reproductive
success among individuals within a population.
So, consider the "red" population.
7
Selection will favor organisms that REDUCE the
frequency and intensity of the competitive
interaction. They can do this "resource
partitioning"

resource axis
remember, selection is differential reproductive
success among individuals within a population.
So, consider the "red" population. Some
organisms are only competing with other "red"
organisms...
8
Selection will favor organisms that REDUCE the
frequency and intensity of the competitive
interaction. They can do this "resource
partitioning"

resource axis
remember, selection is differential reproductive
success among individuals within a population.
So, consider the "red" population. Some
organisms are only competing with other "red"
organisms...while other "red" organisms are
competing with other "red" organisms AND with
"black" organisms...
9
Selection will favor organisms that REDUCE the
frequency and intensity of the competitive
interaction. They can do this "resource
partitioning"

resource axis
remember, selection is differential reproductive
success among individuals within a population.
So, consider the "red" population. Some
organisms are only competing with other "red"
organisms...while other "red" organisms are
competing with other "red" organisms AND with
"black" organisms. So, within the red population,
those in the blue box have less competitive
stress and they can reproduce more than those in
the green box.
10
Selection will favor organisms that REDUCE the
frequency and intensity of the competitive
interaction. They can do this "resource
partitioning"

resource axis
remember, selection is differential reproductive
success among individuals within a population.
So, consider the "red" population. Some
organisms are only competing with other "red"
organisms...while other "red" organisms are
competing with other "red" organisms AND with
"black" organisms. So, within the red population,
those in the blue box have less competitive
stress and they can reproduce more than those in
the green box. They will increase in frequency
and those in the green box will decrease in
frequency...
11
Selection will favor organisms that REDUCE the
frequency and intensity of the competitive
interaction. They can do this "resource
partitioning"

resource axis
remember, selection is differential reproductive
success among individuals within a population.
So, consider the "red" population. Some
organisms are only competing with other "red"
organisms...while other "red" organisms are
competing with other "red" organisms AND with
"black" organisms. So, within the red population,
those in the blue box have less competitive
stress and they can reproduce more than those in
the green box. They will increase in frequency
and those in the green box will decrease in
frequency...and the distribution will shift.
12
Since this is true for BOTH species, both species
may shift away from one another thus reducing
overlap in resource use. This is RESOURCE
PARTITIONING.

resource axis
resource axis
13
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

- the nature of the interaction - the
selective pressures Selection will favor
organisms that REDUCE the frequency and intensity
of the competitive interaction. They can do this
"resource partitioning" - use a different
resource - use the resource at a different time
("temporal partitioning") - use the resource in
a different place ("territoriality")
14
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

- the nature of the interaction - the
selective pressures Selection will favor
organisms that REDUCE the frequency and intensity
of the competitive interaction. They can do this
"resource partitioning". Often, when organism or
species shift to another resource, selection
favors changes in morphology that increase the
efficiency of using this new resource. THIS IS
CALLED CHARACTER DISPLACEMENT.
15
CHARACTER DISPLACEMENT.

each species has rather similar, medium bills
when they are on different islands.

16
CHARACTER DISPLACEMENT.

each species has rather similar, medium bills
when they are on different islands. But when they
are in the presence of a competitor (each other),
each species shifts in bill size AWAY FROM the
size of the competitor,

17
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

- the nature of the interaction - the
selective pressures - outcomes - reduction
in body size or population size of inferior
competitor. - competitive exclusion of the
inferior competitor - resource partitioning
18
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

- the nature of the interaction - the
selective pressures - outcomes -
competition in a variable environment
19
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

- the nature of the interaction - the
selective pressures - outcomes -
competition in a variable environment Because
tolerance ranges of species vary, and because
environments vary, competitive outcomes can vary.
Species 1 might "win" in one environment, but
species 2 might "win" in another environment.
20
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

- the nature of the interaction - the
selective pressures - outcomes -
competition in a variable environment Because
tolerance ranges of species vary, and because
environments vary, competitive outcomes can vary.
Species 1 might "win" in one environment, but
species 2 might "win" in another environment.
- examples of competition
21
Empirical Tests of Competition 1. Gauss P.
aurelia vs. P. caudatum
P. aurelia outcompetes P. caudatum.
22
Empirical Tests of Competition 1. Gauss P.
aurelia vs. P. bursaria
 
 
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P. aurelia vs. P. bursaria coexistence
)  
 
24
Empirical Tests of Competition 1. Gauss Why do
the outcomes differ? - P. aurelia and P.
caudatum feed on suspended bacteria - they feed
in the same microhabitat on the same things. P.
bursaria feeds on bacteria adhering to the glass
of the culture flasks.
)  
 
25
Empirical Tests of Competition 1. Gauss Why do
the outcomes differ? - P. aurelia and P.
caudatum feed on suspended bacteria - they feed
in the same microhabitat on the same things. P.
bursaria feeds on bacteria adhering to the glass
of the culture flasks. - Gauss concluded that
two species using the environment in the same way
(same niche) could not coexist. This is the
competitive exclusion principle.
)  
 
26

• Competition between two species of flour beetle
  Tribolium castaneum and T. confusum.

Empirical Tests of Competition 1. Gauss 2.
Park
 
Competitive outcomes are dependent on complex
environmental conditions
 
Tribolium castaneum
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Empirical Tests of Competition 1. Gauss 2.
Park 3. Connell
)  
   
 
28
3. Connell - reciprocal transplant experiments
Fundamental Niches defined by physiological
tolerances
)  
 
progressively more stressful exposed longer
29
3. Connell - reciprocal transplant experiments
Realized Niches defined by competition
)  
 
Balanus excludes Chthamalus and limits it to more
stressful habitat
30
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

2. Predation (including herbivory and
parasitism)
- the nature of the interaction In these
interactions, one organism BENEFITS (gets a meal)
and the other organism is negatively effected
(loses tissue or it's life).
31
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

2. Predation (including herbivory and
parasitism)
- the nature of the interaction In these
interactions, one organism BENEFITS (gets a meal)
and the other organism is negatively effected
(loses tissue or it's life).
32
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

2. Predation (including herbivory and
parasitism)
- the nature of the interaction - the
selective pressures So, the predator is selected
to increase the frequency of the interaction,
while the prey is selected to decrease the
frequency of the interaction.
33
Selection will favor prey that REDUCE the
frequency and intensity of predation.

interaction axis
resource axis
34
Selection will favor prey that REDUCE the
frequency and intensity of predation. But this
puts a selective pressure on the predators those
that still interact with the prey have an
advantage, and THEIR population shifts...

interaction axis
resource axis
35
and the cycle continues if the variation
exists... this is called an "ARMS RACE" or
positive feedback loop. It differs from
competition.

interaction axis
resource axis
36
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

2. Predation (including herbivory and
parasitism)
- the nature of the interaction - the
selective pressures - outcomes - prey
has reduced size/reproduction - prey goes
extinct - equilibrium (often fluctuating over
time) - prey escapes interaction
37
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

2. Predation (including herbivory and
parasitism)
- the nature of the interaction - the
selective pressures - outcomes -
examples
38
Laboratory Experiments 1. Gauss P. caudatum
(prey) and Didinium nasutum (predator)

   
 
39
Laboratory Experiments 1. Gauss P. caudatum
(prey) and Didinium nasutum (predator) In
initial experiments, Paramecium populations would
increase, followed by a pulse of Didinium, and
then they would crash.
   
 
40
Laboratory Experiments 1. Gauss P. caudatum
(prey) and Didinium nasutum (predator) In
initial experiments, Paramecium populations would
increase, followed by a pulse of Didinium, and
then they would crash. He added oats to the
bottom, creating a REFUGE that the predator did
not enter.
   
 
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Laboratory Experiments 1. Gauss He induced
oscillations by adding Paramecium as 'immigrants'

   
 
42
E. Laboratory Experiments 1. Gauss 2. Holyoak
and Lawler-1996 Used a bacteriovore ciliate,
Colpidium striatum as the prey and our old friend
Didinium nasutum as the predator.
   
 
43
E. Laboratory Experiments 1. Gauss 2. Holyoak
and Lawler-1996 Used a bacteriovore ciliate,
Colpidium striatum as the prey and our old friend
Didinium nasutum as the predator. Set up
replicate 30mL bottles, linked together by tubes,
and single flask systems.
   
 
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Found that Subdivided systems persisted 2X as
long as single systems.
   
 
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Found that Subdivided systems persisted 2X as
long as single systems. Indeed, dispersal was
more rapid from sites containing predators than
from sites without. A key difference is that
there is no permanent refuge the prey just stays
ahead by recolonizing at a faster rate. Preds
don't disperse if prey are present.
   
 
46
Natural Experiments 1. Kelp and Urchins In
1940's
   
 
47
Natural Experiments 1. Kelp and Urchins In
1940's
LA and SD kelp beds began to decline. It was
attributed to the effects of sewage outflow. It
turned out that it WAS the effluent, but only
indirectly.
   
 
48
Natural Experiments 1. Kelp and Urchins In
1940's
LA and SD kelp beds began to decline. It was
attributed to the effects of sewage outflow. It
turned out that it WAS the effluent, but only
indirectly. It turns out that urchins, which are
the major predators of kelp, can also feed on
suspended particulates (sewage). So, the sewage
provided an alternative food resource, raising
the K for the urchins, whcih them exerted a
greater predation pressure on kelp.
   
 
49
Natural Experiments 1. Kelp and Urchins In
1940's
LA and SD kelp beds began to decline. It was
attributed to the effects of sewage outflow. It
turned out that it WAS the effluent, but only
indirectly. It turns out that urchins, which are
the major predators of kelp, can also feed on
suspended particulates (sewage). So, the sewage
provided an alternative food resource, raising
the K for the urchins, whcih them exerted a
greater predation pressure on kelp. Urchins could
stay abundant even while kelp continued to
decline.
   
 
50
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

2. Predation (including herbivory and
parasitism)
3. Mutualism - nature of the
interaction Both organisms/species benefit from
the interaction
51
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

2. Predation (including herbivory and
parasitism)
3. Mutualism - nature of the
interaction - Selective pressures So, both
organisms or species are selected to maximize the
interaction... those that work together do better
than those who work alone.
52

interaction axis
interaction axis
53
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms 1. Competition

2. Predation (including herbivory and
parasitism)
3. Mutualism - nature of the
interaction - Selective pressures -
Outcomes Altruism and helping behavior are
adaptive among relatives or reciprocating
organisms. Species adapting to others can evolve
dependencies in which they ultimate NEED one
another.
54
Corals and zooxanthellae
Aphid farming by ants
Frugivory
Gleaners
Pollination
Protozoans in Termites
55
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms C. Complex Interactions 1.
Non-additive Competition

56
Worthen and Moore (1991)
Indirect, non-additive competitive effects. D.
falleni and D. tripunctata each exert negative
competitive effects on D. putrida in pairwise
contests, but D. putrida does better with BOTH
competitors present than with D. tripunctata
alone
 
   
focus just on "number", the open column (not
hatched)
 
NON-ADDITIVE
ADDITIVE
57
Worthen and Moore (1991)
Indirect, non-additive competitive effects. D.
falleni and D. tripunctata each exert negative
competitive effects on D. putrida in pairwise
contests, but D. putrida does better with BOTH
competitors present than with either alone
 
D. putrida
D. tripunctata
   
 
Because D. falleni exerts a negative influence on
D. tripuncata, it weakens the effect that D.
tripunctata can have on D. putrida. Thus, the
presence of D.falleni has an indirect positive
effect on D. putrida that outweighs its direct
negative effect.
D. falleni
58
I. What is Ecology? II. Ecological Interactions
A. With the Abiotic Environment B. With
Other Organisms C. Complex Interactions 1.
Non-additive Competition 2. "Keystone" Predation

59
2. Keystone Predators Paine (1966) - the rocky
intertidal
60
Paine (1966) - the rocky intertidal - Pisaster
prefers mussels
61
B. Keystone Predators Paine (1966) - the rocky
intertidal - Pisaster prefers mussels - When
predators are excluded, mussels outcompete other
species and the diversity of the system crashes
to a single species - a mussel bed
62
B. Keystone Predators Paine (1966) - the rocky
intertidal - Pisaster prefers mussels - When
predators are excluded, mussels outcompete other
species and the diversity of the system crashed
to a single species - a mussel bed - When
predators are present, the abundance of mussels
is reduced, space is opened up, and other
species can colonize and persist.
63
B. Keystone Predators Paine (1966) - the rocky
intertidal - Pisaster prefers mussels - When
predators are excluded, mussels outcompete other
species and the diversity of the system crashed
to a single species - a mussel bed - When
predator is present, the abundance of mussels is
reduced, space is opened up, and other species
can colonize and persist. So, although Pisaster
does eat the other species (negative effect) it
exerts a bigger indirect positive effect by
removing the dominant competitor
64
So, although Pisaster does eat the other
species (negative effect) it exerts a bigger
indirect positive effect by removing the dominant
competitor
Predator
Predation
Predation
( - )
( - )
( )
( - )
Dominant Prey
Subordinant Prey
competition
65
I. Climate II. Biomes III. Productivity,
Diversity, and Stability
66
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity
67
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 1.
Gross Primary Productivity Total photosynthetic
productivity CO2 H20 -----gt Glucose O2
68
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 2.
Net Primary Productivity NPP GPP -
respiration (Plants use some of the energy they
absorb it is not stored as biomass. NPP is only
the amount stored as new biomass.
69
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity -
remember Energy Budgets??
Metabolism
Growth
Reproduction
70
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity -
remember Energy Budgets??
Metabolism
Growth
GPP
Reproduction
71
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity -
remember Energy Budgets??
RESPIRATION ------
Metabolism
Growth
GPP
NPP
Reproduction
72
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 3.
Net Secondary Productivity NSP Amt. of
energy animals STORE
73
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 3.
Net Secondary Productivity NSP Amt. of
energy animals STORE What would this depend
on....???????
74

ANY DIFFERENCES, ENERGETICALLY???
75
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 3.
Net Secondary Productivity NSP Amt. of
energy animals STORE What would this depend
on....??????? ("warm-blooded" animals waste more
energy as heat, and store less as biomass....)
76
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 4.
Why does this matter??????????
77
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 4.
Why does this matter?????????? a. NPP is the
energy available to higher trophic levels.
(Can't eat "heat")
78
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 4.
Why does this matter?????????? a. NPP is the
energy available to higher trophic levels.
(Can't eat "heat") b. NPP is the energy
available to human civilizations.... as food,
timber, etc....
79
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 5.
Consequences a. trophic "pyramids"
80
a. trophic "pyramids"
NPP of Producers (PLANTS)
81
a. trophic "pyramids"
Loss due to 2nd Law
NSP of HERBIVORES
NPP of Producers (PLANTS)
82
a. trophic "pyramids"
NSP of Primary Carnivores
Loss due to 2nd Law
NSP of HERBIVORES
NPP of Producers (PLANTS)
83
a. trophic "pyramids"
NSP of Secondary Carnivores
Loss due to 2nd Law
NSP of Primary Carnivores
NSP of HERBIVORES
NPP of Producers (PLANTS)
84
a. trophic "pyramids"
This is why large carnivores are RARE, and why
they have large RANGES
NPP of Secondary Carnivores
Loss due to 2nd Law
NPP of Primary Carnivores
NPP of HERBIVORES
NPP of Producers (PLANTS)
85
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 5.
Consequences b. food webs
86
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 5.
Consequences b. food webs - more energy
available lower
87
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity 5.
Consequences b. food webs - mammal food
chains are short - fish, insect chains are
longer (less energy is lost as heat more is
available to higher levels, can support more
levels....)
88
5. Consequences b. food webs - mammal
food chains are short - fish, insect chains
are longer (less energy is lost as heat more is
available to higher levels, can support more
levels....) - it's not this clean... there are
omnivores, detritivores, scavengers, etc.
89
5. Consequences b. food webs - mammal
food chains are short - fish, insect chains
are longer (less energy is lost as heat more is
available to higher levels, can support more
levels....) - it's not this clean... there are
omnivores, detritivores, scavengers, etc. -
bigger base, more levels....
90
5. Consequences b. food webs - So, where
should food webs be longer, the tropics or
poles?
91
5. Consequences b. food webs - So, where
should food webs be longer, the tropics or poles?
(Tropics - more energy at base, web dominated by
reptiles and insects, rather than mammals as in
the temperate zone and poles.)
92
5. Consequences a. trophic "pyramids" b. Food
Webs 6. Human Concerns
93
5. Consequences a. trophic "pyramids" b. Food
Webs 6. Human Concerns a. Food is NPP or NSP.
94
5. Consequences a. trophic "pyramids" b. Food
Webs 6. Human Concerns a. Food is NPP or
NSP. b. More efficient to eat lower on the food
chain, but modernization correlates with
increased meat in diet. (Meat production is
increasing FASTER THAN population growth... and
grazing lands increasing...)
95
I. Climate II. Biomes III. Productivity,
Diversity, and Stability A. Productivity B.
Diversity
96
B. Diversity 1. Measurements
97
B. Diversity 1. Measurements a. Species
Richness ( of species)
98
B. Diversity 1. Measurements a. Species
Richness ( of species) b. Relative
Abundance is important
99
B. Diversity 1. Measurements a. Species
Richness ( of species) b. Relative
Abundance is important
Habitat 1
Habitat 2
Simpson's Diversity D 1/S(p2)
50
99
species A
1
species B
50
Richness
2
2
Simp. Div.
2
1.02
100
B. Diversity 1. Measurements a. Species
Richness ( of species) b. Relative
Abundance is important
c. Genetic diversity within species
Habitat 1
Habitat 2
50
99
species A
1
species B
50
Richness
2
2
Simp. Div.
2
1.02
101
B. Diversity 3. Relationships with Productivity
102
B. Diversity 3. Relationships with
Productivity a. Productivity increases
diversity
(this is right... I don't know why I had a brain
spaz in class... I was seeing a "with diversity"
that just .. well... isn't there....)
103
B. Diversity 3. Relationships with
Productivity a. Productivity increases
diversity - QUANTITATIVE EFFECT If you have
more productivity at the base of a food web, then
you can build a longer food chain (adding
additional levels AND species).
104
B. Diversity 3. Relationships with
Productivity a. Productivity increases
diversity - QUALITATIVE EFFECT An increase in
productivity may also occur because more types of
food have been added. This may allow for more
specialization at the next trophic level - and
the coexistence of more species.
105
B. Diversity 3. Relationships with
Productivity a. Productivity increases
diversity b. Diversity increases productivity
106
B. Diversity 3. Relationships with
Productivity a. Productivity increases
diversity b. Diversity increases
productivity - Sampling Effects More diverse
communities are more likely to contain the most
productive species, and thus raise the total
productivity.
107
B. Diversity 3. Relationships with
Productivity a. Productivity increases
diversity b. Diversity increases
productivity - Niche Complementarity More
diverse communities are more likely to contain
different types of species that use different
types of energy... thus more efficiently
harvesting the available energy
108
Monoculture
Polyculture
They all need the same things at the same
concentrations have to place them far apart to
reduce competition.
Combinations of different plants can be planted
at higher density, and they use different
"niches" and coexist. Even if abundance of "most
productive" species, drops, this loss can be
offset.
109
B. Diversity 3. Relationships with
Productivity a. Productivity increases
diversity b. Diversity increases
productivity - Positive Interactions More
diverse communities may contain species that
benefit other species, and thus increase the
productivity of the whole community
110
Monoculture
Polyculture
without beans
with beans
They all need the same things at the same
concentrations have to place them far apart to
reduce competition.
Nitrogen fixing legumes (beans) nutrify the soil,
increasing the growth of other plants
111
Study Questions 1) How can competition act as a
selective force and cause a species to change
over time? 2) Why are competitive outcomes
determined by the environmental conditions? 3)
Describe how the presence of a predator can cause
species diversity to increase. 4) How can the
addition of a superior competitor increase the
success of an inferior competitor? 5) How does a
"keystone species" increase diversity in a
system? 6) How do qualitative and qualitative
increases in productivity increase diversity. 7)
How do the selective pressures in a predator prey
relationship differ from the pressures in a
mutualism? 8) How can a more diverse community be
more productive that a monoculture of your most
productive plant, and why.