Fill in the blanks for lecture 4

Question 1

Stressors include what? (4)

Answer 1

Habitat loss, invasive species, climate change, overharvesting

Question 2

Ecosystem functions are what?

Answer 2

Stocks and fluxes of energy and materials (ex: biomass, productivity, nutrient cycling), stability, invasibility

Question 3

Biodiversity ecosystem function hypothesis (BDEF): a reduction in biological diversity (variety of species, genotypes, ect.) will cause a _______ __ ________ _____ _________.

Answer 3

reduction in ecosystem level processes

Question 4

There are 3 classes of BDEF hypotheses:

1) Species are primarily ______
- loss of species is ___________ for by other species; or, the addition of such species adds nothing new

Answer 4

Redundant; compensated

Question 5

Redundant species: a species could be lost “without much effect on the ______ ___ ______ of the whole community.

Answer 5

structure and function

Question 6

3 classes of BDEF hypotheses:

2) Species are primarily ________
- Species contribute to ecosystem functioning in _______ ____, their loss or addition causes detectable changes.

Answer 6

unique ways

Question 7

What are keystone speices?

Answer 7

A species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically.

Question 8

Keystone species are most attributable to which class of BDEF hypothesis?

Answer 8

2) Species are primarily singular

Question 9

3 classes of BDEF hypotheses:

3) Species impacts are context-dependent and therefore ___________.
- The impact of loss or addition of a species depends on ______ _________. (ex: composition)

Answer 9

unpredictable; local conditions

Question 10

Assumptions of BDEF:

1) _______ is changed at a scale relevant to ecosystem functions

Answer 10

diversity

Question 11

Assumptions of BDEF:

2) Reductions in commonly measured ecosystem variables are ___________.

Answer 11

undesirable

Question 12

Ecosystem functioning is divided into 3 classes:

1) Stocks of _______ and ________ (ex: biomass)
2) ______ of energy or material processing (ex: productivity, decomposition, nutrient cycling)
3) ________ of rates or stocks over time (ex: invasion resistance)

Answer 12

1) energy and materials
2) Fluxes
3) Stability

Question 13

What are the different properties of stability?

Answer 13

Resilience, resistance, robustness, persistence.

Question 14

_________ - a measure of the speed at which an ecosystem returns to its original state after a disturbance.

Answer 14

resilience

Question 15

_________ - a measure of the degree of disturbance a system can withstand before switching to another state.

Answer 15

robustness

Question 16

__________ - a measure of the ability of a system to maintain itself through time.

Answer 16

Persistence

Question 17

________ - a measure of the ability of a system to maintain its original state in the face of a disturbance.

Answer 17

resistance

Question 18

Diversity and stability: communities with more species are buffered against:

1) _________
2) ________
3) _________ __________

Answer 18

1) extinctions
2) invasions
3) environmental perturbations

Question 19

__________ effect: explains why more diverse systems are more stable.

Answer 19

portfolio effect

Question 20

The portfolio effect can be described as:
A broadly diverse portfolio _____ less over time (y) than if you invested only 1 or 2 stocks.
As you average more stocks (or more species), they become _____ variable.
Nature, like a stock, has _____ and ____ years.

Answer 20

1) varies
2) less
3) good;bad

Question 21

Ecosystem stability: treatment plots with _____ diversity were 70% more stable in biomass production than __________.

Answer 21

high; monocultures

Question 22

______ ___________: niche differentiation between species or genotypes allows for more efficient exploitation of resources.

Answer 22

niche complementarity

Question 23

Examples of niche complementarity (i.e. lack of niche overlap) are?

Answer 23

Utilization of the same resource differently, foraging in different ways, use different life stages of prey, use different part of the plant (resource).

Question 24

________ ______: species that are redundant in functional roles or capacity respond differently to stressors.

Answer 24

Insurance effects

Question 25

niche complementarity hypothesis: combinations of species that differ in _______ ___ (low niche overlap) have greater impact on ecosystem function.

Answer 25

Resource use

Question 26

When species niche overlap is low, expect ______ differences in ecosystem functioning.

Answer 26

large

Question 27

Evidence for niche complementarity:

1) ______ ________
2) ______ relationship between species richness and ecosystem functioning

Answer 27

1) transgressive overyielding

2) positive

Question 28

_______ _____________ plays a role in the way algal species diversity improves water quality (via nitrate uptake).

Answer 28

niche complementarity

Question 29

Ecosystems with ______ _______ are more efficient at removing nutrients from soil and water than ecosystems with _______ ________.

Answer 29

more species; fewer species

Question 30

_______ habitats: more niche opportunities for species to coexist.

Answer 30

heterogeneous

Question 31

Streams with heterogeneous habitats allow ________ _________ among algal species.

Answer 31

resource partitioning

Question 32

A single species becomes dominant in ___________ habitats.

Answer 32

homogeneous

Question 33

Mechanisms that stabilize ecosystem functions via increased diversity:
_______ _________ can stabilize communities through omnivory or the buffering of strong interactions by weak interactions.
_____ _____ ______ ______ tend to stabilize food webs and characterize more diverse communities.

Answer 33

1) multitrophic interactions

2) low mean interaction strengths

Question 34

Monoculture:
_______ environment for many natural enemies.
Has been suggested that by ________ plant diversity, natural enemy numbers will ________ with a corresponding ________ in herbivore numbers.

Answer 34

1) hostile

2) increasing; increase; decrease

Question 35

What is this bitche’s favourite model organism?

Answer 35

Dicyphus hesperus

Question 36

________ design: species densities are constant across treatments.

Answer 36

substitutive

Question 37

Temporal stability of individual species populations: equation?

Answer 37

S(i) = u(i) (mu)/sigma(i)
mu(i) is the mean abundance of species i
sigma(i) is its temporal standard deviation

Question 38

Individuals species show higher stability in _________ than in ________.

Answer 38

polyculture; monoculture

Question 39

Overall, ________ shows an increase in stability relative to __________.

Answer 39

polyculture; monoculture

Question 40

Conclusions (Brommit et al.)
1) Herbivore population stability ________ with increased diversity
2) Specialist parasitoid population stability ______ with increased diversity
3) omnivore population stability _______ with increased diversity
thus,
4)

Answer 40

increases for the 1-3

4) each trophic level stability increases with plant diversity

Question 41

______ ________ increases withe the number of resident species.

Answer 41

biotic resistance

Question 42

________ resistance increases with species richness.

Answer 42

invasion

Question 43

Mechanism: diversity and invasibility (i.e. decrease in invasion success by exogenous plant species)

1) _______ in root biomass
2) ______ in available nitrate in plots

Answer 43

1) increase

2) decrease