LEC 20

Question 1

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

Answer 1

What they eat and what eats them

Question 2

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

Answer 2

Autotrophs

Question 3

The first (basal) trophic level consists of _____________

Answer 3

Autotrophs (primary producers)

Question 4

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

Answer 4

Chemical energy (NPP)

Question 5

All other trophic levels consists of

Answer 5

Heterotrophs (consumers)

Question 6

The second trophic level includes _______ that feed on _______-

Answer 6

Herbivores, autotrophs

Question 7

The third trophic level includes __________ that feed on ___________-

Answer 7

Carnivores, herbivores

Question 8

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

Answer 8

Carnivores, other carnivores

Question 9

There are ______________

Answer 9

Levels within levels

Question 10

Some organisms do not fit conveniently into trophic levels

Answer 10

Omnivores feed at multiple levels:

Coyotes are examples of omnivores, consuming:

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

Question 11

All organisms in an ecosystem are either __________________ or ________________________

Answer 11

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

Question 12

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

Answer 12

Consumed, detritus

Question 13

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

Answer 13

Decomposers (detritivores), decomposition

Question 14

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

Answer 14

First, detritivores, second

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

Question 15

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

Answer 15

Trophic pyramids, energy or biomass

Question 16

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

Answer 16

Lost, energy pyramids, inverted

Question 17

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

Answer 17

Biomass pyramids, inverted

Question 18

Examples are usually ______________

Answer 18

Aquatic (marine, specifically)

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

Question 19

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

Answer 19

~10%

Question 20

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:

Answer 20

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

Question 21

Consumption efficiency

Answer 21

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)

Question 22

Assimilation efficiency

Answer 22

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)

Question 23

Assimilation efficiency is __________ in carnivores than herbivores because:

Answer 23

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

Question 24

Production efficiency

Answer 24

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

Question 25

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

Answer 25

GREATER; produce much more heat

Ectotherms gain heat from surroundings, not food

Question 26

Trophic efficiency =

Answer 26

Consumption efficiency x assimilation efficiency x production efficiency

Question 27

Trophic efficiency ranges from ~1% to ~20%

Answer 27

Average trophic efficiency is 10%

Question 28

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

Answer 28

four or five

Question 29

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

Answer 29

90%

Question 30

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

Answer 30

direct interaction

Question 31

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

Answer 31

Third (or more)

Question 32

Trophic cascades are _________ involving multiple predator and prey species

Answer 32

Indirect interactions

Question 33

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)

Answer 33

third, decreases, second, increases, first

Question 34

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

Answer 34

trophic interactions

Question 35

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

Answer 35

Qualitatively

Question 36

As _____ increases in food web diagrams, so does ___________

Answer 36

Realism, complexity

Question 37

Considering ________________ together reveals keystone species and dominant species

Answer 37

Trophic pyramids, indirect effects, and food webs

Question 38

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

Answer 38

their abundance or biomass might suggest

Tend to be HIGHER trophic level

Question 39

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

Answer 39

Robert Paine’s

Question 40

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

Answer 40

Top carnivores; keystone predator

Question 41

__________ were determined to be keystone species in the intertidal

Answer 41

Sea stars

Question 42

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

Answer 42

High abundance or biomass

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