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Flashcards in Final Deck (170)
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1
Q

What is nutrition mutualisms?

A

Two species exchange nutrients, or one species is rewarded in some way for improving the nutritional status of another

2
Q

What are some examples of nutrition mutualisms?

A
  • mycorrhizae and N2 fixing bacteria
  • Corals- symbiosis with zooxanthellae
  • deep sea tube worms
3
Q

Mutualism will only arise if

A

pw(sm) + qw(um) > w(nm)

  • w(nm): fitness of individuals in a nonmutualistic population
  • p: proportion of successful mutualists (W(sm))
  • q: proportion of unsuccessful mutualists (w(um))
4
Q

The major exploitative interactions include

A

predation, herbivory, and parasitism

5
Q

Key predator adaptations affect the ___, ___, and ___ of prey.

A

detection, capture, consumption

6
Q

Mutualisms generally evolve to facilitate

A

reproduction, energy/nutrient acquisition, or protection from exploitative interactions

7
Q

Mutualisms can be

A

obligate or facultative; specialized or general

8
Q

What is an ecological community?

A

a group of interacting species that co-occur in a particular place

9
Q

What parameters describe communities?

A
  • composition: what species are present?

- structure: how do those species interact with each other?

10
Q

What is direct filtering determined by?

A

environmental tolerances of the species

11
Q

What is indirect filtering mediated by?

A

interactions with other species that are subject to filtering

12
Q

What do neutral models of community composition assume?

A
  • communities are random combos of species physiologically able to live in the same place
  • two mechanisms determine species membership in communities- dispersal in ecological time and speciation in evolutionary time
  • if communities are altered, they do not necessarily recover the same community structure
13
Q

What do niche-based models of community composition assume?

A
  • biological interactions (ex: competition) shape (and are shaping) the niches of coexisting species and so determine community composition
  • “ghost of competition past” may give the appearance of competition not being important in the current community (i.e. that niches are already well separated or even randomly distributed) via competitive exclusion and character displacement some time in the past
14
Q

Under a neutral model of community structure

A

species associate at random

15
Q

In a neutral model

A

the niches are arranged at random, so that some niches are very similar, and others very different

16
Q

In a niche-based model

A

the niches are over- or hyper-dispersed in niche space

17
Q

Which is more likely: competitive hierarchy or competitive networks?

A

competitive networks

18
Q

Coexistence is possible by ___ the niche

A

subdividing

19
Q

Coexistence is also possible is resources are ___ and OVERALL niche overlap is ___

A

abundant; small

20
Q

What are some ways to pack species into diverse communities?

A
  • increase overlap: possible if resources (k) are large enough and overlap does not exceed some threshold
  • decrease niche breadth: a.k.a. become more specialized
    • can happen via character displacement
  • extend range along resource axis: a.k.a exploiting resources not used by other species
    • can happen via character displacement/directional selection
21
Q

Environmental filtering and competition have ___ effects on community composition

A

opposing

22
Q

If environmental filtering dominates over competition,

A

phylogenetic clustering is more likely

-closely related groups will have similar traits and so pass through environmental filter together

23
Q

If competition dominates over environmental filtering,

A

phylogenetic over- dispersion is more likely

-only phylogenetically and therefore ecologically different species are found within guilds in the community

24
Q

What is community heritability?

A

the proportion of the variation in a characteristic of the community (such as herbivore diversity) that is explained by genetic variation in the population of a particular species (e.g. plants)

25
Q

How does community heritability affect community structure?

A

via “community genetics”

26
Q

What is facilitation?

A

a process in which the presence of one species INCREASES the probability that another occurs in the community, usually by mediating competition

27
Q

How does mutualism operate like facilitation?

A

lessens the effects of competitive interactions

28
Q

What are keystone predators?

A

eat other competitively dominant predators, thus allowing coexistence of a diverse community

29
Q

What is apparent competition?

A

two similar species are negatively impacted by the action of a shared predator or herbivore
-good example of an indirect interaction between two species (one that is mediated via another species)

30
Q

Any process that increases the resource base or decreases the degree to which a resource is limiting will ___ the impact of competition

A

reduce

31
Q

Where is competition most important?

A

at equilibrium

32
Q

Disturbances may affect

A

limiting resources

33
Q

Disturbances can temporarily ___ the resource base

A

increase

34
Q

Disturbance can delay the process of

A

competitive exclusion

35
Q

The first determinant of species presence or absence in a community is

A

whether or not it can survive the physical conditions (environmental filtering)

36
Q

Neutral models of community structure posit that communities are

A

random assemblages of species that can tolerate the abiotic conditions

37
Q

What are key determinants of the community composition in neutral models?

A

dispersal and environmental filtering

38
Q

Communities structured by competition are affected by both

A

competitive exclusion and character displacement

39
Q

Competition in a community leads to

A
  • increased niche overlap
  • decreased niche breadth
  • increase in the range of resources used
40
Q

The effect of competition on community structure can be modified by other interactions, such as

A
  • predation
  • facilitation
  • apparent competition
41
Q

If resources are not limiting, the role of competition in structuring the community is

A

reduced

42
Q

How does disturbance reduce the effect of competition?

A

by increasing the levels of important resources

43
Q

Disturbances initiate changes in community structure via

A

removal of individuals

44
Q

What is succession?

A

the sequence of changes in a community following a disturbance

45
Q

What is a successional stage called?

A

a seral stage

46
Q

What do serial stages form together?

A

sere

47
Q

What axes are disturbances characterized along?

A
  • size
  • intensity
  • frequency
48
Q

Primary succession follows a disturbance that is

A

so severe that the new conditions are nearly abiotic

49
Q

What is an important characteristic of primary succession?

A

soil is lost or destroyed

50
Q

When does secondary succession occur?

A

When the disturbance isn’t as severe as primary succession, such that functional soil (and its seed bank) remains intact)

51
Q

What are some examples of primary succession?

A

glaciers, volcanic eruptions

52
Q

What are some examples of secondary succession?

A

windthrow, fires

53
Q

Effect of crown fire

A
  • Variation in impact: high-intense crown fire to cool ground fire
  • Delayed mortality: no
  • Mode of recovery: dispersal
  • Recovery rate: rapid
  • Plant species dominance: changes in herbaceous species; not trees
  • Regional diversity: increases
  • Local diversity: initially decreases
54
Q

Effect of a hurricane

A
  • Variation in impact: low (within boundaries of storm; higher at distance from eye)
  • Delayed mortality: yes
  • Mode of recovery: resprouting + seeds
  • Recovery rate: very rapid
  • Plant species dominance: shifts due to pulse of early successional species
  • Regional diversity: increases
  • Local diversity: little change
55
Q

Effect of a volcano

A
  • Variation in impact: highly variable as function of distance from blast zone
  • Delayed mortality: no
  • Mode of recovery: dispersal
  • Recovery rate: slow but variable
  • Plant species dominance: shifts with succession
  • Regional diversity: increases
  • Local diversity: initially decreases
56
Q

What is resistance?

A

the degree to which the community withstands disturbance

57
Q

What is resilience?

A

the speed with which a community can recover from disturbance
-depends on nature of disturbance and traits of organisms, which interact over evolutionary time

58
Q

What are two examples of chronosequences?

A

Hawaii and the Lake Michigan dunes

59
Q

What is a climax community?

A
  • the final stage of succession

- the community that replaces itself and that cannot be invaded by other species

60
Q

What does the Clementsian paradigm state?

A

disturbance is infrequent; stability of the climax is the norm

61
Q

T or F? It has been shown that disturbance, rather than stability, is the norm

A

T

62
Q

What is a disclimax?

A

a successional stage that persists due to recurrent disturbance

63
Q

What does a Gleasonian paradigm state?

A
  • instead of a highly regulated, predictable pattern of vegetation, community composition is dependent on chance events
  • the random occurrence of disturbance events
  • the chance events associated with colonization and individual successional sequences
  • communities rarely reach equilibrium
  • Rejection of simple, fixed chronosequences and focus on the spatial rather than temporal dynamics of plant communities
  • Succession is complex, unpredictable, and site specific
64
Q

What does patch dynamics describe?

A

a spatial mosaic of areas at different stages of probabilistic succession

65
Q

What are some environmental effects of disturbance?

A
  • increased light availability
  • loss/gain of nutrients or interruption of nutrient cycles
  • succession itself: the biotic community in flux as succession proceeds
66
Q

When does the facilitation model of succession apply?

A

if the disturbance produces a physical environment in which colonization and survival are especially difficult
-pioneer species facilitate colonization by later successional species

67
Q

The inhibition model is driven by

A

the ability of species to colonize the disturbed site and then resist invasion by other species

68
Q

The tolerance model states that

A

species replacement only occurs when new species are more tolerant of the newly changed conditions and replace earlier species

69
Q

What is an example of the inhibition model?

A

colonization following disturbance of the rocky intertidal zone (in this env, space is the limiting factor)

  • the green alga, Ulva spp., is an early colonist that inhibits invasion by the red algae common later in succession
  • if Ulva is experimentally removed, red algae quickly colonize
70
Q

What’s the difference between primary and secondary succession?

A

primary: occurs following disturbances that revert the ecosystem to abiotic conditions
secondary: follows less severe disturbances

71
Q

Disturbances vary according to

A

intensity, spatial scale, and frequency

72
Q

Although many intense, widespread disturbances are relatively rare, most communities are affected by

A

frequent disturbance of some kind

73
Q

Communities are typically a mosaic of

A

recently disturbed and undisturbed sites

74
Q

___ and ___ characterize community responses

A

resistance; resilience

75
Q

When time since disturbance changes linearly over space,

A

a chronosequence develops

76
Q

What is a chronosequence?

A

a set of communities in different stages of succession as a function of distance from the disturbance

77
Q

In primary succession, pioneer species must be able to

A

tolerate harsh abiotic conditions

78
Q

Why is secondary succession generally more rapid than primary succession?

A

because the soil is relatively intact and the physical conditions are more conducive to plant growth

79
Q

The final, self-perpetuating stage of succession is

A

the climax community

80
Q

The theory of patch dynamics characterizes communities on the basis of

A

size, isolation, and successional status of patches within the habitat

81
Q

Resource conditions change as a result of

A

disturbance

82
Q

Plants that colonize early in succession are adapted to exploit

A

the high-light conditions and thrive in often low-nutrient conditions

83
Q

Plants that occur later in succession are

A

more efficient in their use of light but cannot grow as fast when light is abundant

84
Q

Some early successional species are

A

fugitive species; their habitat disappears as succession proceeds, making population persistence dependent on dispersal to newly disturbed sites

85
Q

Three key mechanisms of successional change are described by

A

the tolerance, facilitation, and inhibition models

86
Q

How do we define species diversity?

A
  • species richness: the number of species

- species evenness: the relative abundance of species

87
Q

What is alpha diversity?

A

the species richness of a single community at one site

88
Q

What is beta diversity?

A

the change in species composition across several adjacent communities

89
Q

What is gamma diversity?

A

the total diversity among a group of different communities on a landscape scale

90
Q

What is community composition?

A

the species that are found in a community (a species list)

91
Q

What is species endemism?

A

the number of species endemic (i.e. unique) to the region

-a result of evolutionary history, including isolation

92
Q

What is biodiversity?

A

the total biological diversity in a community, including species diversity and genetic diversity

93
Q

Why can describing communities be difficult?

A
  • cryptic species
  • complex life cycles
  • poor taxonomic understanding
94
Q

How is species richness typically measured/shown?

A

lognormal species curves: reveal a common pattern in the structure of most communities

  • most species occur at moderate abundance
  • few species are very rare or very common
95
Q

What is the effect of sample size on lognormal species curves?

A

Preston’s “veil line”

96
Q

What is the Shannon-Weaver Index of Species Diversity?

A

H ‘ = −∑^n p(i) ln(pi)
n: number of species in the community
p(i): the frequency of the ith species

97
Q

What is a Rank-Abundance curve?

A

a plot of the log proportional abundance of each species as a function of its ranked abundance (most to least abundant)
-the slope of this curve is a measure of species evenness

98
Q

How are species richness and area related?

A
S = cA^z
S: number of species
A: area
z: slope of the line (usually lies between 0.2 and 0.35)
c: constant
99
Q

Low species richness is an inherent property of

A

islands

100
Q

The number of species on an island is determined by the relationships between

A

the immigration and extinction rates and the relative size of the species pool

101
Q

Small and distant islands have ___ species than large and near islands

A

fewer

102
Q

The farther the island from mainland, the ___ the probability that a dispersing individual will arrive

A

lower

103
Q

Small islands have a ___ extinction rate

A

higher

104
Q

What are the processes controlling species diversity at large scales?

A
  • speciation

- extinction

105
Q

What are the processes controlling species diversity at small scales?

A
  • colonization
  • extirpation (of non-endemic species)
  • speciation (e.g. on islands)
106
Q

What does the allopatric speciation model describe?

A

Situation in which a geographic barrier separates two populations of a species

  • reproductive isolating mechanisms arise
    • post-mating isolating mechanisms
    • pre-matching isolating mechanisms
107
Q

What is WBI?

A

wild bird species index

108
Q

What is WPSI?

A

waterbird population status index

109
Q

What is LPI?

A

a measure of vertebrate diversity

110
Q

What is RLI?

A

red list index, a measure of extinctions

111
Q

What are autotrophs?

A

organisms that obtain energy (and carbon) from inorganic sources, such as by chemo- or photosynthesis

112
Q

What are the ultimate biological source of energy for ecosystems?

A

autotrophs

113
Q

What is primary production?

A

the energy that autotrophs acquire (or carbon-fix) from the inorganic environment

114
Q

What is gross primary production (GPP)?

A

the total rate of carbon fixed by autotrophs

115
Q

What is net primary production (NPP)?

A

the total rate of carbon fixed by autotrophs minus the carbon they respire
(NPP=biomass)

116
Q

What are heterotrophs?

A

organisms that obtain energy (and carbon) from organic compounds, generally from other organisms, living or dead

117
Q

What is secondary production?

A

the production of biomass by heterotrophs

118
Q

Chemoautotrophs derive energy from

A

the oxidation of electron donors in the environment

119
Q

What are example of electron donors?

A

hydrogen (H2), hydrogen sulfide (H2S), methane (CH4)

120
Q

What are examples of electron acceptors?

A

O2, NO3, SO4

121
Q

Photoautotrophs derive energy from

A

sunlight (through photosynthesis)

122
Q

Both chemoautotrophs and photoautotrophs use energy to fix

A

CO2 as a source of carbon

123
Q

What is the energy flow through ecosystems?

A
3rd consumer (4th TL)
            ^
2nd consumer (3rd TL)
            ^
1st consumer (2nd TL)
            ^
1st producer (1st TL)
           ^
Solar energy

*TL: trophic level

124
Q

What is the equation for ingestion efficiency?

A

E(ingested)/E(available)

125
Q

What is the equation for assimilation efficiency?

A

E(assimilated)/E(ingested)

126
Q

What is the equation for production efficiency?

A

E(in new tissue)/E(assimilated)

127
Q

What does a food web do?

A

summarizes the feeding relationships in a community (who eats who)

128
Q

What is one of the most basic and revealing descriptions of community structure?

A

food webs

129
Q

What is omnivory?

A

feeding at more than one trophic level

130
Q

What are stable isotopes?

A

non-radioactive forms of biologically important elements

  • carbon (C12 and C13)
  • nitrogen (N14 and N15)
131
Q

The trophic position of an organism can be quantified on the basis of its ___ ratio

A

N15/N14

  • N14 is lost in urine at a higher rate than N15, making higher trophic levels progressively heavier in N15
  • ratio of N15/N14 increases up the food chain relatively predictably
132
Q

The max efficiency of plant photosynthesis is between

A

4.6 and 6%

133
Q

What are the most important selective forces on plants?

A

the combined effects of low CO2, limited water, and high temperature

134
Q

C4 pathways in plants are favored

A

at low CO2 and high temperature

135
Q

What are ecological factors limiting primary production?

A

-light
-water
-temp
*actual evapotranspiration (AET)- the total amount of water that evaporates and transpires from a region per unit time- correlates with NPP
-nutrients
ALL REPRESENT BOTTOM-UP CONTROL

136
Q

Nutrients, particularly ___, control phytoplankton biomass in lake ecosystems

A

phosphorous

137
Q

The highest rates of NPP are also related to high levels of

A

nutrient availability

138
Q

The highest rates of NPP are concentrated on

A

continental shelves (because of terrestrial run-off) and upwelling zones

139
Q

In open oceans, primary production is limited by

A

very low concentrations of nutrients

140
Q

Vertical mixing (and entrainment of deep nutrient-rich water) is prevented by a permanent ___ in tropical oceans, resulting in the lowest levels of marine primary production

A

thermocline

141
Q

What are the three hypotheses about what determines food chain length?

A

Hypoth 1: ecosystems with higher primary production have longer food chains
-pred 1: food chain length inc with primary prod but not with ecosystem size
Hypoth 2: larger ecosystems have longer food chains
-pred 2: food chain length inc with ecosystem size but not with primary prod
Hypoth 3: production and ecosystem size interact
-pred 3: food chain length inc with both primary prod and ecosystem size

142
Q

What is was determined by data to be the actual determinant of food chain length?

A

ecosystem size

143
Q

What is a food chain?

A

hierarchical pattern in which energy passes from producers to consumers

144
Q

What limits the number of trophic levels along food chains?

A

inevitable energy losses

145
Q

Each transfer of energy among trophic levels results in

A

energy lost to higher trophic levels

146
Q

Ecosystems vary widely in their rate of

A

primary production

147
Q

Any factor that limits photosynthesis or plant growth may limit

A

primary production

148
Q

Plants face strong selection to increase their acquisition of

A

light, water, and nutrients

149
Q

Ecosystems differ in the number of __ __ they contain

A

trophic levels

150
Q

Biogeochemical cycles

A

describe the cyclic movement of nutrients in ecosystems, in which elements and compounds are exchanged among the principal pools (atmosphere, rocks, soil, water, and organisms)

151
Q

What are the principle pools?

A

atmosphere, rocks, soil, water, and organisms

152
Q

Pools are expressed as an

A

amount per unit area

153
Q

Pools are linked by

A

fluxes (rates expressed as amount per unit per unit time)

154
Q

Biogeochemical cycles are ___ at the global scale

A

closed

155
Q

Biogeochemical cycles can operate (and be studied) at any

A

spatial scale

156
Q

Why is carbon important?

A

it’s the primary component of biomolecules that form the basis of life

157
Q

Why is nitrogen important?

A

vital for amino and nucleic acids

158
Q

Why is phosphorous important?

A

essential for phospholipids, ATP, ATP and nucleic acids

159
Q

T or F? Nitrogen and phosphorous are available at unlimited quantities

A

F

160
Q

The global carbon cycle is driven by

A

photosynthesis and respiration

161
Q

Equation for photosynthesis/respiration?

A

—>photosynthesis

6CO2 + 6H2O C6H12O6 + 6O2

162
Q

What is the equation for nitrogen fixation?

A

N2 + 8H+ + 8e- –> 2NH3 + H2

163
Q

Nitrogen fixation is energetically expensive because

A

triple bond between atoms must be broken

164
Q

What are some other pathways in the N cycle?

A
  • microbial and plant uptake
  • decay and ammonification
  • NH3 –> nitrite –> nitrate
  • dentirification
  • nitrate –> nitrite –> NO + N2O –> N2
165
Q

Dentrification

A
  • is anaerobic
  • requires an organic C source
  • is how N2 is returned to the atmosphere
166
Q

Phosphorous is an important component of

A

nucleic acids, cell membranes, and energy conversions

167
Q

Is there a significant atmospheric pool of phosphorous?

A

no

168
Q

Movement of nutrients through ecosystems is

A

cylic

169
Q

Biogeochemical cycles are characterized by

A
  • pools or sinks (components of the ecosystem where the nutrients reside)
  • fluxes (the pathways of transfer among pools)
170
Q

Decomposition releases organic nutrients into

A

the soil or water, where they can be taken up again