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Ecology - Dynamics > Populations - Food Webs > Flashcards

Populations - Food Webs Flashcards

1
Q

Food Chains

A

Representations of extension of competition beyond own trophic levels.

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2
Q

Carnivore in food webs…

A

Consume herbivores, influence plant communties.

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3
Q

Understand aspects of food webs…

A

Removal of a species; a predator increase of prey

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4
Q

Trophic Cascade

A

A preadtor-prey effect that later abundance biomass or productivity of a population community or trophic level across one or more link in a food web.

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5
Q

Analysing dynamics with trophic cascades….

A

Isolation of a portion of a habitat and removal of one species

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6
Q

Four trophic level systems cascading…

A

Top-predator increase leads to second-level predator decrease then herbivore increase, with plant abundance decreasing.

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7
Q

Mesopredator release

A

A phenomenon where populatiosn of medium-sized predators rapidly increase in ecosystems ater removal of top carnivores.

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8
Q

Example of apex predator removal with mesopredator thriving…

A

Cats and fox are preyed on by dingoes(prey on same animals) so dingoes regulate mesopredators.

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9
Q

Top-down control

A

Predation by higher trophic levels affecting the accumulation of biomass at lower trophic levels.

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10
Q

Bottom-Up Control

A

Domination of the lower trophic levels typically plants or the herbivores.

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11
Q

Distinction between community and species level trophic cascades.

A

Community predators predate herbivores, controlling aabundance, releasing pressure on plants from control
Species increase in predator decreases herbivore increasing plant abundance

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12
Q

Ecosystem Exploitation Hypothesis

A

Says that plant biomass reflects the primary productivity of an ecosystem modified by the regulating effect of herbivory

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13
Q

Describing structure of a community…

A

Interaction strengths, food chain length and number of species.

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14
Q

Ecosystem Stability

A

Measures susceptiblity to disturbance

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15
Q

Different types of disturbances of stability?

A

Pulse Events and Press Events

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16
Q

Pulse Events

A

Abrupt changes in ecological parameters

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17
Q

Press Events

A

Persistent changes determining community state

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18
Q

Ecosystem Resistance

A

The extent of which a community is altered by a disturbance.

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19
Q

Ecosystem Resillience

A

The speed of communities return to the former state after disturbance

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20
Q

Ecosystem Robustness

A

Tendency of communities to suffer secondary/subsequent extinctions following primary extinctions

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21
Q

Keystone Species

A

Species that have a disproportional effect on their ecosystem in regards to their abundance.

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22
Q

Foundation Species

A

Differ in that they are spatially dominant creating physical structures with their own body tissue

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23
Q

Three parameters describing food webs…

A

S - Number of species
C - Connectance of the web
Beta - Average interaction strenght

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24
Q

Relation of instability to connectance and interaction stregnth…

A

The two increase instability as species increase.

25
Q

Portfolio Effect

A

This is where more diversity fares better with changing conditions.

26
Q

What enhances stability?

A

Ecological processes like increase in richness, competitiveness.

27
Q

Complementary Effect

A

This is resource partioning or positive interactiosn leading to increased total resource use

28
Q

What drives the complementary effect?

A

Niche differentaiton.

29
Q

Selection Effect

A

Dominance by species with particular traits affecting ecosystem processes

30
Q

Transgressive overyielding.

A

This occurs when mixture performance exceeds that of the best performing sole crop.

31
Q

Insurance Hypothesis

A

This may be how more diverse plant ecosystems photosynthesise at a greater rate than ecosystems with fewer species present.

32
Q

Basis of insurance hypothesis…

A

Responding differently to external influences based on species richness

33
Q

Compartmentalization of food webs…

A

Into subunits where within interactions are strong, but between interactions are weka.

34
Q

Why does compartmentalization increase stability?

A

More ribustness against removal and knock on effects are more limited against perturbationss

35
Q

Food Chain Length

A

Describes the number of feeding links from a basal species to a top predator.

36
Q

10% Rule

A

This descriebs how only 10 percent of energy stored as biomass in a trophic level is passed from one level to the next

37
Q

Productive Space Hypothesis

A

Predicts food chain length is determined by productivty per unit area multiplied by the space occupied in the ecosystem

38
Q

Larger ecosystems influence on food chain length…

A

Larger niche trophic diversity or reduced disturbance reverberations

39
Q

Evolutionary constraints on predators…

A

Who they can consume by capture, subuding and consumption adaptations, and the hunting of herbivores, with competition arising

40
Q

Parasites effects on food webs

A

Higher diversity and higher complexity

41
Q

Regime Shifts

A

These are large, abrupt, persistent changes in structure/function of complex systems.

42
Q

Regime shifts and small disturbances…

A

Small disturbances can drive dramatic shifts when tipping poitns exist.

43
Q

What is an example of a trophic cascade?

A

Yellowstone wolf extinction in early 1900s

44
Q

What is a real example of Mesopredator release?

A

Serengeti loss of lions and hyenas increased jackal/mongoose abundance leading to less smaller mammals and birds.

45
Q

What is an example of top-down control in ecosystem?

A

Herbivorous zooplankton in lakes controlling algal biomass.

46
Q

Where can bottom-up control be applied?

A

67 forests data determine climate effects like temperature and precipitation, with increasing nutrient cycling with temperature with alterations by precipitation also.

47
Q

Ecosystem Exploitation Hypothesis

A

This describes how more complex ecosystems reocver from exploitation and resists it better than simple ones.

48
Q

What is complexity of an ecosystem given by?

A

Amount of species and number of interactions between them.

49
Q

Why does resilience increase with complexity?

A

Energy/resource pathways more widely avaiable and greater adaptive capacity.

50
Q

Jacobian Matrix

A

This assesses stability of dynamic systems descriing how rates of change of each species abundace are influenced by changes in abundances of all other species in the web.

51
Q

How does jacobian matrix model food webs?

A

Takes partial derivatives of species per capita growth rate with repsect to abundace of every other species in the web.

52
Q

What is food web stability in Jacobian Matrix given by?

A

Eigenvalues

53
Q

Partial Derivatives

A

This is the derivative of a function of several variables with respect to change in just one of its variables.

54
Q

Eigenvalues

A

These are vectors that can only be scaled lengthwise without rotation after applying the matrix transformation.

55
Q

Matrix

A

A rectangular array of numbers/symbols or expressions arranged in rows and columns.

56
Q

What if eigenvalues are negative?

A

System is table and can return to equilibrium when perturbed

57
Q

How can jacobian matrix be used to identify keystone species??

A

Largest magnitude eigenvalues mean they removal have significant impacts.

58
Q

Insurance Hypothesis

A

This proposes that number of speceis in an ecosystem increases, the ecosystem becomes more resistant and resilient.

Ecology - Dynamics (9 decks)

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