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Flashcards in LEC 20 Deck (42)
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1
Q

Trophic interactions are feeding relationships that link organisms in an ecosystem based on _________________________

A

What they eat and what eats them

2
Q

Each trophic level, or feeding category, is based on the number of steps by which it is separated from the _________ in the ecosystem

A

Autotrophs

3
Q

The first (basal) trophic level consists of _____________

A

Autotrophs (primary producers)

4
Q

The first trophic level generates __________ using sunlight (photosynthesis) or inorganic molecules (chemosynthesis)

A

Chemical energy (NPP)

5
Q

All other trophic levels consists of

A

Heterotrophs (consumers)

6
Q

The second trophic level includes _______ that feed on _______-

A

Herbivores, autotrophs

7
Q

The third trophic level includes __________ that feed on ___________-

A

Carnivores, herbivores

8
Q

The fourth (and higher) trophic levels include _________ that feed on _______________

A

Carnivores, other carnivores

9
Q

There are ______________

A

Levels within levels

10
Q

Some organisms do not fit conveniently into trophic levels

A

Omnivores feed at multiple levels:

Coyotes are examples of omnivores, consuming:

  • Autotrophs (fruits, berries)
  • Herbivores (Grasshoppers)
  • Carnivores
  • Old leather boots
11
Q

All organisms in an ecosystem are either __________________ or ________________________

A

Consumed by other organisms, enter the pool of dead organic matter (detritus)

12
Q

In any ecosystem, only a small portion of NPP is _________, while most ends up as ________-

A

Consumed, detritus

13
Q

Dead plant, animal, and microbial matter (detritus), as well as wastes (feces), are consumed by ___________________ during the process of ____________

A

Decomposers (detritivores), decomposition

14
Q

Detritus is considered part of the _______ trophic level, so ___________ are included with the ______ level

A

First, detritivores, second

Understand that detritus does NOT have any NPP, but still can be considered on the first trophic level

15
Q

A ___________ is a graphical representation of __________________ with respect to trophic relationships

A

Trophic pyramids, energy or biomass

16
Q

Because a proportion of the energy at each trophic level is _____ during transfer to the next trophic level, _____________ may never be ________-

A

Lost, energy pyramids, inverted

17
Q

It is possible for ___________ to be _________ (more biomass at higher trophic levels)

A

Biomass pyramids, inverted

18
Q

Examples are usually ______________

A

Aquatic (marine, specifically)

-Large baleen whales feeding on tiny phyto- or zooplankton with short lifespans and high turnover

19
Q

Only ________ of energy from the first trophic level makes it to the next trophic level

A

~10%

20
Q

Trophic efficiency is a measure of how much energy from one trophic level makes it to the next trophic level. Trophic efficiency consists of three components:

A

1) Consumption efficiency
2) Assimilation efficiency
3) Production efficiency

21
Q

Consumption efficiency

A

Measures how much energy at one trophic level is consumed by the next trophic level

Ranges from ~5% to ~50% in different ecosystems

The rest of the energy is simply not eaten

All autotrophic energy may not be consumed by herbivores due to:

  • The autotrohp’s chemical (screenplay compounds) and physical (spines and thorns) defenses
  • Nutrient-poor components (wood) compared to nutrient-rich components (leaves)
22
Q

Assimilation efficiency

A

Measures how much energy from one trophic level is incorporated into the next trophic level by digestion and used for maintenance and defense

Ranges from ~20% to ~80%

The energy that is not assimilated is lost as wastes (feces)

23
Q

Assimilation efficiency is __________ in carnivores than herbivores because:

A

GREATER;
Plant matter contains much indigestible material, such as cellulose and lignin

Animals have similar carbon to nitrogen ratios as the carnivores consuming them, so they can more easily be assimilated

24
Q

Production efficiency

A

Measures how much energy from one trophic level goes into the production of new biomass for the next trophic level (in the form of growth and reproduction)

Ranges from ~1% to ~50%

The rest of the energy is lost as heat during cellular respiration

25
Q

Production efficiency is ___________ in ectotherms than in endotherms because endotherms ___________________ during metabolism

A

GREATER; produce much more heat

Ectotherms gain heat from surroundings, not food

26
Q

Trophic efficiency =

A

Consumption efficiency x assimilation efficiency x production efficiency

27
Q

Trophic efficiency ranges from ~1% to ~20%

A

Average trophic efficiency is 10%

28
Q

There are usually no more than _______ trophic levels in any ecosystem

A

four or five

29
Q

QWith ________- of the energy lost at each trophic level, there is not enough energy (NPP) remaining to support any additional levels

A

90%

30
Q

Predation (as well as competition, mutualism, etc.) are _____________ between two species

A

direct interaction

31
Q

Indirect interations occur when the relationship between two species is mediated by a ___________ species

A

Third (or more)

32
Q

Trophic cascades are _________ involving multiple predator and prey species

A

Indirect interactions

33
Q

In the simplest type of trophic cascade, predation by a carnivore (_____ trophic level) ______ the number of herbivores (____ trophic level), which in turn _______ the number of autotrophs (____ trophic level)

A

third, decreases, second, increases, first

34
Q

A food web is a conceptual diagram of the ________ among organisms in an ecosystem

A

trophic interactions

35
Q

A food web shows ________ how energy flows from one member of an ecosystem to another

A

Qualitatively

36
Q

As _____ increases in food web diagrams, so does ___________

A

Realism, complexity

37
Q

Considering ________________ together reveals keystone species and dominant species

A

Trophic pyramids, indirect effects, and food webs

38
Q

Keystone species are those species that have a greater influence on energy flow and ecosystem composition than ______________________

A

their abundance or biomass might suggest

Tend to be HIGHER trophic level

39
Q

____________ 1966 intertidal study was the first to introduce the concept of keystone species

A

Robert Paine’s

40
Q

Keystone species tend to be _______________ (leading to the common term ________________)

A

Top carnivores; keystone predator

41
Q

__________ were determined to be keystone species in the intertidal

A

Sea stars

42
Q

Dominant species (AKA foundation species) are those species that have large effects on energy flow and ecosystem composition due to their _____________________

A

High abundance or biomass

Dominant species tend to be autotrophs
-Tend to be first trophic level