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ecology exam 2 and 3 > module 12 > Flashcards

module 12 Flashcards

1
Q 
exploration can affect
competition
consumer-resource(exploitation)
detritivore-detritus
mutualism
A 
a population
(-)(-)
(+)(-)
(+)(0)
(+)(+)
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2
Q 
Exploitation
predators
parasistes
parasitoids
pathogens
A

Interaction between populations
Enhances fitness of one individual while reducing fitness of the exploited individual.
Predators – Kill and consume other organisms.
Parasites – live on host tissue and reduce host fitness
Do not generally kill the host.
Parasitoid – insect larva that consumes the host.
Pathogens induce disease.

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3
Q

3 Feeding Methods of Heterotrophs:

A

Herbivores: Feed on plants.
Carnivores: Feed on animal flesh.
Detritivores: Feed on non-living organic matter.

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4
Q 
Herbivory
grazing
browsing
granivore
frugivory
nectivory
A 
Consumption of plants or plant parts
Grazing – eating grass or forbs
Browsing – Eating leave or young shoots
Granivory – seed predation
Frugivory – consumption of fruiting bodies
Nectivory – consumption of nectar
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5
Q

Substantial nutritional chemistry problems
Plant composition differs from Animal composition
-plants have ____ concentrations
must overcome plant defenses
physical and chemical

A

low nitrogen concentrations

Must overcome plant defenses
Physical
Thorns
Waxes & Resins
Cellulose, lignin, silica

Chemical
Toxins
Digestion Reducing Compounds

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6
Q 
Detritivores
consume food rich in 
often poor in
dead leaves has
fresh detritus may still have
A

Consume food rich in carbon and energy
Often poor in nitrogen
Dead leaves may have half nitrogen content of living leaves.
Fresh detritus may still have considerable chemical defenses present.

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7
Q

Carnivores
consume ______ preg
can’t choose prey at will

A 
Consume nutritionally-rich prey
Cannot choose prey at will
-Availability & Capturability of prey
-Risk involved
-Select whole organisms
Not nutrients

-Most are well balanced nutrtionally
May selectively consume parts

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8
Q

predators and seed predators

A

high probability of death low duration of association

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9
Q

parasitoids

A

high death high association

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10
Q

grazers and browsers

A

low death short duration

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11
Q

parasites and anrthropod herbivores

A

low death high high durations

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12
Q

Parasites That Alter Host Behavior

A

Spring-Headed Worm (Acanthocephalans)

  • Changes behavior of amphipods
  • Make it more likely that infected amphipods will be eaten by a suitable vertebrate host.
  • Infected amphipods
  • Swim toward light
  • Usually indicative of shallow water
  • Closer to predators.

-make it susceptible to predators to continue life cycle and spread

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13
Q

Herbivores Effect on Plants

short term effects

A 
Short Term Effects
-strict negative-decreases when fed on
compensation
Morphological & physiological adjustments counter losses up to a threshold
-compensate for loss
-after a while can't compensate

Overcompensation
increase in performance, growth, or fitness under low to moderate grazing
Long Term Effects?

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14
Q

why does Compensation occur

A

increased Plant Activity
Timing & Intensity
Increased Ecosystem Functioning

-nutrients go back to increase production through feces or death

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15
Q

Elton

and Keith

A

proposed driven by variation in solar radiation.
increase radiation, increase production-population goes up at the same time cycle

Keith-
Suggested overpopulation theories:
Decimation by disease and parasitism.
Physiological stress at high density.
Starvation due to reduced food.
-overpopulation occurs decrease because of stress disease starvation
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16
Q

Snowshoe Hares - Role of Food Supply

A 
In winter browse on buds and stems 
Shrubs and saplings 
such as aspen and spruce
2 Effects
Greatly reduce Food Supply 
Greatly reduce food biomass 
Late November = 530 kg/ha 
Late March = 160 kg/ha
~ 70% reduction in food supply
Alter Food Supply
Shoots produced after heavy browsing 
Increase levels of plant chemical defenses
Reducing usable food supplies

-increase chemical defenses when hares feed heavily, this makes it harder to get nutrients and causes decrease of hares- easy to prey Ono

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17
Q

Snowshoe Hares - Role of Predators

A

Predation
60-98% of mortality during peak densities.-easier prey since they have no more nutrients they ate it all
Lynx
Classic specialist predator
Other Specialist predators have similar responses
Coyotes may also play a large role.

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18
Q

Complementary role of predations & Food:
Hare populations increase
Causes:

A

Food supplies to decrease
Starvation and weight loss
May lead to increased predation
All decrease hare populations

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19
Q

Lotka-Volterra assumes Host population :

limited by

A

Grows exponentially

limited by parasites, pathogens, and predators:

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20
Q

rhNh =

A

Exponential growth by host population.

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21
Q

Opposed by:
p =
Nh =
Np =

A 
p =  rate of parasitism / predation.
Nh = Number of hosts.
Np = Number of parasites / predators.
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22
Q

Lotka Volterra assumes:

Parasite/predator growth rate is determined by:

A
  • Rate of conversion of food into offspring

- Minus mortality rate of parasitoid population:

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23
Q

c p Nh Np

A

Conversion rate of hosts into offspring.

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24
Q

p Nh Np

A

Rate at which exploiters destroy hosts.

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25
c=
Conversion factor | -Rate at which prey biomass transformed into predator offspring
26
Model Behavior Host(prey) population dynamics more predators= larger predator population eventually in turn ______ predator population
Growth -Exponential - Growth opposed by exploitation. - -Host reproduction immediately translated into destruction by predator. - --Increased predation = more predators. - --More predators = higher exploitation rate. - --Larger predator population eventually reduces host population - --In turn reducing predator population.
27
increase in predation=_______ in exploration | decrease prey=_____ predators consumption
increase in exploitation | decrease predators consumption
28
Reciprocal effects produce oscillations in two populations.
Assumptions of Lotka-Volterra Result in: Eternal oscillations Neither host nor exploiter populations are subject to carrying capacities -prey and predator balance each other out
29
Assumptions of Lotka-Volterra | Unrealistic
- Lack of Carrying Capacity - No consideration of Outside Factors -Valuable contributions to the field
30
Animals Respond to Changing Food Densities in one of 2 ways
Functional Response | Numerical Response
31
Numerical Response | as prey pop. increases
A change in the population size of a predator species as a result in the density of its prey -Migration -Population Growth predator pop. increases
32
Functional Response
A change in the rate of exploitation of prey by an individual predator as a result in a change in prey density
33
``` Holling described (3) basic functional responses: Type I. ```
- Feeding rate increases linearly as food density increases - levels off at maximum. - Consumers require little or no search and handling time. - filter feeders whale - constant linear
34
Type II.
Feeding rate rises in proportion to food density | Feeding rate partially limited by search/handling time
35
Type III.
Feeding rate increases most rapidly at intermediate densities (S-shaped).
36
Type II Functional response Trade-offs of Time Constraints Th and TS
``` Handling Time (Th) Search Time (Ts) ```
37
Hollings Disc Equation E H A
E = (aHT) / (1 + aHTh) E – Number of Encounters H – Prey Density a – Searching Efficiency
38
handling time longer = | handling time smaller=
less encounter | more encounter, more prey attack
39
Type III Functional Response | Low prey density
Low prey density -Predators respond slowly Intermediate prey densities -Consumption rate highest Allows Regulation of Prey populations -Pressure Relieved at low Densities
40
Factors for Type III -prey vulnerability search time and motivation search an capture vulnerability
Prey Vulnerability - Heterogeneous Habitat - >Limited Hiding Cover Search Time & Motivation to Hunt prey item -Search Image Search & Capture Vulnerability - Lack of Reinforcement of Search Behavior - Prey Switching
41
Search Images | high densities _____search images
- A behavioral prey selection mechanism - -Enables predators to increase searching efficiency for prey that are abundant and worth capturing - High Densities reinforce Search Images -select prey that are more abundant and worth capturing
42
Prey switching
- Predators often choose most abundant prey in greater proportion than it is found - Energetic Constraints
43
Optimal Foraging Theory
- Predators Choose Food items - Confronted with numerous Choices - -Potential Cost - -Exposure to risks (predation, injury, etc.) - -Energy Expenditure - Potential Benefits - Choice Minimizes Cost relative to Benefits - Predicts that natural selection molds foraging behavior to maximize fitness -maximize fitness by choosing prey that gets more energy in than they put out
44
Optimality Modeling Assumes consumers make choices no necessarily
Assumes consumers make choices Not Necessarily Conscious ``` Based on: Recent Experience Physiological State Ability to capture Proximate Feedbacks Search Image ```
45
Principle of Allocation | organisms must
Assumes if energy supplies are limited, organisms cannot simultaneously maximize all life functions. Organisms Must: -Compromise between competing demands -Reduce Relative Cost for Foraging
46
most beneficial are prey that are
intermediate in size
47
forage on animals that
that have the greatest return
48
Should predator consume prey item? energy intake ______ by diet breadth factors to consider for prey:
-Energy intake optimized by diet breadth --# of different prey items in diet Factors -Prey energy content -Prey Escape ability -Prey abundance
49
search time decreases when
there is more food availability
50
Prey Model only applies to . herbivores rather alter when should a consumer leave a patch
Predators - Herbivores generally do not alter food choice - Rather Alter Forage Patches When should a consumer Leave a Patch? - Most Prey items occur in patches - Predators deplete Prey abundance Patch-use Model -Central-place Foraging Model
51
Consumer should leave patch when
profitability of patch < surrounding area
52
Giving-up time
- Amount of time that a foraging animal stays in a patch before leaving to find another patch - Balances rate of gain in current patch to travel time (cost) to next profitable patch - Assumes Animal knows the profitability of surrounding patches ?????
53
Risk-Sensitive Foraging risk-averse risk-prone
Risk-averse -Individual takes fewer risks but achieves lower net gain Risk-Prone -Individual takes more risks but achieves higher net gain Strategy depends on Needs of Individual -Chooses Strategy that allows best survival
54
Gause | Attempted to produce population cycles with P. caudatum and Didinium nasutum.
``` Gause Attempted to produce population cycles with P. caudatum and Didinium nasutum. Didinium quickly consumed all Paramecium Went extinct -Both populations extinct ```
55
To persist in the face of exploitation: | hosts need
``` Hosts and prey need refuges Gause Added sediment for Paramecium refuge. Didinium went extinct Paramecium thrived initially Eventually went extinct ```
56
Must add | stable cycling requires:
refuges and immigration to maintaining long term
57
what is needed in the system along with immigration and refugee
complexity
58
Predators & Prey Defense based on selective pressures for prey need to be what to survive predators
- Predators usually selection agents for refined prey defense. - -Must catch and subdue prey - -Usually eliminate more conspicuous (less adaptive) members of a population - Selective pressures for - -Size - -Behavior - -Defensive structures -prey need to be fit to survive predators
59
Predator & prey species are engaged in
a co-evolutionary race.
60
Prey Defenses: group defense color defense cryptic colaration aposematic coloration
- Group Defense (Flocking) - -Predator Confusion - -Group Awareness ``` Coloration Cryptic Coloration -Blend into background Aposomatic Coloring -Warning colors ```
61
Mimicry - mullerian - Batesian
-Mullerian mimicry Comimicry among several --species of noxious organisms. -Batesian mimicry --Harmless species mimic noxious species.
62
Protection in Numbers Predator satiation defense -can ____ the ____ of being eaten
- Living in a large group provides a “refuge.” - Predator’s response to increased prey density: - Wide variety of organisms employ predator satiation defense. - Prey can reduce individual probability of being eaten by living in dense populations.
63
Masting Janzen O’Dowd and Gill
Synchronous, widespread seed & fruit production Proposed that seed predation is a major selective force favoring mast crop production. Determined synchronous seed dispersal by Eucalyptus reduces losses of seeds to ants. -drop all at once to make it into the soil
64
cicadas show
predator satiation Emerge as adults every 13-17 years. Densities can approach 4x106 ind / ha. -brias can't evolve to take a strategy emergence too long
65
Size As A Refuge
-If large individuals are ignored by predators -Large size may offer a form of refuge. Peckarsky Observed mayflies (Family Ephenerellidae) make themselves look larger in the face of foraging stoneflies. -In terms of optimal foraging theory, large size equates to lower profitability. increase size lower energy probability

ecology exam 2 and 3 (10 decks)

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