Final Exam - Community Ecology - Lecture 14 - Fill in the Blanks Flashcards Preview

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Flashcards in Final Exam - Community Ecology - Lecture 14 - Fill in the Blanks Deck (53):
1

Food chain length depends on the amount of ________ _________ ________ (_).

Potential primary productivity or G

2

What are the names of the four major hypotheses on why food chain lengths differ?

1 - Energy limitation hypothesis
2 - Dynamic stability hypothesis
3 - Ecosystem size hypothesis
4 - Productive space hypothesis

3

_____ _______ hypothesis: longer food chains are less resilient so disturbance frequency/intensity limit food chain length.

Dynamic stability

4

________ ______ hypothesis: large ecosystems support more individuals and more species.

Ecosystem size

5

______ _______ hypothesis: food webs are inefficient; more productive environments support longer food chains.

Energy limitation

6

_______ ______ hypothesis: ecosystem size and productivity act together.

Productive space

7

To determine which factor affected food chain lengths in lakes, researchers performed treatments that included:
1 - ___________ alone
2 - __________ alone
3 - Combination of 1 and 2
(note that the lines may represent more than one word)

1 - Productivity
2 - Ecosystem size

8

Problems in testing food chain lengths hypotheses has been the inability to measure _____ _____ _____ and _________ _____.

Food chain length and ecosystem size

9

Post et al., used ______ _______ techniques to determine food chain length (maximum trophic position)

stable isotope

10

In stable isotope analysis, Carbon changes little through the food web, but is used to determine sources of _______.

energy

11

Productivity for small, medium and large lakes:
Maximum trophic position did ___ __________ with increased productivity

not increase

12

The conclusions of the Post et al (Stable isotope), study was that:
1 - Found ________ _____ was the ONLY factor that determined food chain length
2 - suggests that factors related to food chain length are not resolved
3 - At present, ________ _____ followed by ________ hypothesis are main factors

1 - ecosystem size
3 - Ecosystem size; productivity

13

Charles Elton on Food Chains vs. Food Webs:
- Food chains were "limited to _____ or _____ ______"
- Several food chains occur linked together as a food web
Chains and webs used to illustrate __________ in _________: (such as predator prey, host/parasitoid and mutualistic relationships)

1 - four or five links
2 - interactions in communities

14

Nodes (S) (definition)

the organisms that occur in the food web

15

Links (L): generally given as arrows to show the direction/strength of the _________ or ___________.

Interaction or relationship

16

Linkage density is given by the equation: _/_.

L/S
where,
L is the number of links and S is the number of nodes

17

What is connectance?

Number of observed links in the network.
(given as a proportion of observed links to total possible links)

18

Increased connectance promotes _________ in the food web.

Stability

19

Chain length: the number of _____ ______ in the chain or web.

Trophic levels

20

Source webs: all species in the web arise from the ______ _______ _______.

Same source species

21

Sink webs: where feeding relationships lead to a _____ ____ ________.

Single top predator

22

Community web (definition)

The entire set of feeding relations possible in a community (never fully realized)

23

Connectedness web:
- illustrate _______ ________
- trophic links are given as arrows pointing to the consumer
- No indication of ________ _________

1) Feeding relationships
2) Interaction strengths

24

Green food webs:
- Food webs with ______ _______ at the base
- _____ energy channels

1) Primary producers
2) fast

25

Brown food webs:
- Food webs with ________ at the base
- ____ energy channels

1) Detritus
2) Slow

26

Energy flow webs:
- illustrate the pattern of _____ _____ through the community
- Difficult to build - it is hard to get such difficult information
- _______ ____ is not a good indicator of _________ _______ between species at different trophic levels
- Considers Lotka's _________ concept of the ecosystem and Odum's depiction of the ecosystem as a _____ diagram

1) Energy flow
2) Energy flow; Interaction strength
3) thermodynamics; flow

27

Food webs are ______.
Energy is lost via:
1) ______ energy - used to produce indigestible structures
2) ______ energy - lost as heat
3) _______ energy - nitrogenous wastes

- inefficient
1) Egested
2) Respired
3) Excreted

28

_________ energy = ingested - egested energy

Assimilated

29

_________ = assimilated - respired - excreted energy

Production

30

Energy available at each level of the food web depends on the ___ ________ ________ at the base of the web and _________ ________ between trophic levels

1) Net primary production
2) Transfer efficiency

31

Plants use 15-70% of the energy they absorb for maintenance = maximum 30-85% for assimilation by herbivores
BUT, energy transfer is ______. Only _-__% of energy available at one level is ________ to the next

Energy transfer is inefficient. Only 5-20% of the energy available at one level is assimilated by the next.

32

What is net production efficiency?

The ratio of energy contained in production to total assimilated energy (= production/assimilated energy)

33

Net production efficiency is ____ for active, warm blooded animals and ____ for sedentary, cold-blooded animals.

1) High
2) Low

34

What is the equation for assimilation efficiency?

Assimilation efficiency = assimilation/ingestion

35

According to Raymond Lindemand, assimilation efficiency is the fraction of energy entering one trophic level that is ______ onto the _____ _____ _____.
Transfer is ________. And this is why food chains are _____.

1) passed onto the next higher level.
2) Inefficient
3) Short

36

Functional webs:
1) illustrate the _______ of populations of each species in the web on the ______ ______ in the web
2) Size of the arrow represents the ________ of the __________
3) Communities include _____ and _____, _____ and _______ interactions.
4) Not all interactions are _______ _________

1) impact; other species
2) strength of the interaction
3) weak and strong; direct and indirect
4) equally important

37

How does one determine interaction strength?
- Experimental manipulation:
1) Remove ______ from the _________ and observe what happens to the other _______

1) Species; community; species

38

Indices of interaction strength:
N = ____ [normal condition] (sentence answer)
D = ______ [Deleted predator]
Y = abundance of _______
Py = proportional abundance of the ________
t = time

N = abundances of prey when predators are present
D = number of prey without predators
Y = abundance of predators
Py = proportional abundance of the predator

39

Paine's index = (N-D)/DY
- Quantifies the effect of the ______ or _______ on the ________ _______ in the community
- The dominant resource has the potential to form a _________ in the ________ of the consumer

1) predator or consumer; dominant resource
2) monoculture; absence

40

Community importance = ((N-D)/NPy))
- Quantifies the effect of a ______ relative to its ________
- Distinguishes ________ from dominant species in the community

1) species; abundance
2) Keystone

41

Dynamic index = ln(N-D)/Yt
- Compares the log ratio of _____ abundance when predators are _______ to when predators are ________

1) Prey abundance when predators are present to when predators are absent

42

What about observational data? (Bascompote et al.)
IS = [(Q/B)j x DCij]/Bi
Where,
IS = ________ _______
Bi = _____ of the ______

IS = interaction strength
Bi = biomass of the prey

43

Functional food webs:
- research has show that, for multiple food webs that:
- most food webs contain a ____ ______ and many ______ links

few strong and many weak links

44

Food web stability:
- simple communities were more prone to _______ _______ and fluctuations in ______ ________

Simple communities are more prone to (species invasions) and fluctuations in (species abundance)

45

Simple communities are ________ communities.
Complexity adds ________ to communities.

1) Unstable
2) Stability

46

Robert May:
Modeled ecosystems by randomly assigning interaction strengths and showed that complex communities were _____ ______.

Less stable

47

McCann et al: weak interactions in complex communities dampen population oscillations = _______ _______

increased stability

48

Ricklefs: an omnivore is an organism with a broad diet, including both plant and animal foods; an omnivore feeds from _______ _______ ______.

Multiple trophic levels

49

Based on theoretic models, Pimm and Lawton predicted that it should be _____ __ ____ species that feed simultaneously both high and low in the food web.

Rare to find

50

Because omnivores can alter their diet, their populations tend to be _____ _____ due to the _______ effect.

More stable = refuge effect

51

Singer and Bernays: Due to switching behaviour, omnivores interact _______ with their food sources
- weak interactions --> _____ food webs

1) Weakly
2) Stable

52

Lafferty et al., estimate that 75% of links in food webs involve parasites:
- including parasites _______ food chain _____ and _______

(Increases) food chain (length) and (stability)

53

If parasites stabilize food webs, why are they not included?
1 - Small in size (hard to identify and quantify)
2 - Complex life cycles
3 - May have multiple hosts at different _____ _____
4 - Energy transfer is _____ to measure because _______ do not _____ their hosts
5 - Parasites affect host behaviour, altering ______ ________

3) trophic levels
4) hard; parasites; kill
5) interaction strengths