Final Exam Flashcards
(115 cards)
1
Q
3 typed of efficiency in trophics efficiency
A
- Consumption: proportion of available energy that is consumed
- Assimilation: proportion of ingested food that is assimilated
- Production: proportion of assimilated food that goes into producing biomass
2
Q
Agents of change
A
- act on all communities across all temporal and spatial scales
- can be abiotic (increases in sea level, warmer temp, pollution fires) or biotic (competition, mutualism, predation)
3
Q
Where are all nutrients derived from
A
Abiotic sources: minerals in rocks and gases in atmosphere
4
Q
Allocation of NPP
A
- growth
- storage (starch) provides insurance against loss tissues to herbivores, disturbances and climatic effects
5
Q
Allochthonous input
A
External energy input
-ex. Much of detritus in streams, lakes, rivers is derived from terrestrial organic matter
6
Q
Alternative stable states
A
- different communities follow different successional paths develop in same area under similar similar environmental conditions
- does not change backwards
7
Q
Assimilation efficiencies of herbivores and carnivores
A
- animals have carbon:nutrient ratios similar to the animals they consume
- herbivores and detritivores 20-50% (lower)
- carnivores 80%
8
Q
Assimilation efficiencies of endothermic and ectotherm
A
- endothermic digest goods more completely and have higher assimilation efficiencies
- endotherms also use this to produce heat, more than grow and reproduce
9
Q
Atmospheric deposition includes…
A
Elements in precipitation (wet deposition) or aerosols and fine dust (dry deposition)
10
Q
Atmospheric sources of nutrients
A
- Nitrogen fixation
2. Aerosols/atmospheric decomposition
11
Q
Autochthonous input
A
Energy produced by autotrophs within the system
12
Q
Physiological and biological entities of a community include…
A
Physical: rivers, lakes, deserts, mountains, hot springs
Biological: forests, coral reefs, meadows
13
Q
How to define members of a community
A
Taxonomic affinity: an ecologist may study a butterfly community or bird community
Guild: a group of species that use similar resources (ex. Animals based on diet, plants based on growth forms)
Functional group: their role in community
14
Q
What are food webs
A
Web that incorporates information about relationships among species in terms of energy flow in terms of trophic levels
15
Q
What does the shape of the trophic pyramid represent
A
- relative biomass
16
Q
Interaction web
A
- contain info on energy flow and non trophic interactions
- predation, positive interactions (mutualism and commensalism)
17
Q
How to quantify species diversity
A
Species richness: total number of species
Species evenness: takes into the account the relative abundance of each species in the community
Species diversity: combines the number of species and their relative abundance in the community
18
Q
Species accumulation curve that levels off indicates…
Limitation
A
- The sampling effort has adequately assessed species diversity
- limitation: assumes the sampling methods are consistent through the study
19
Q
Biodiversity
A
- diversity of important biological entities that span from alleles, genes, species and communities
20
Q
Species composition
A
- an element of community structure that describes the identities of organisms within a community
- other elements still contribute to actual species and communities present like species pools, abiotic conditions, nature between species and species already in community
21
Q
Trophic cascade
A
- result of indirect species interaction
- rate of consumption at one trophic level results in change in species abundance at lower trophic level
22
Q
Trophic cascade
A
- result of indirect species interaction
- a consumer is indirectly helped by a positive interaction between its prey and another species
23
Q
Competitive network vs competitive hierarchy
A
Network: no one species dominates, competitive interactions among multiple species in which every species has a negative effect on every other species
Hierarchy: one species always dominates, indirect species interactions buffer strong competition
24
Q
Species interaction strength
A
The effect one species has on the abundance of other species
25
Keystone vs foundation species
Keystone: large effects despite low abundance
Foundation: large effects due to large size or high abundance
26
What are the two categories of abiotic and biotic agents of change
1. Disturbance: event that directly physically injures or kills, creates opportunity for others
2. Stress: factor that reduces the rate of an important physiological process, reducing growth, reproduction or survival
27
What is succession
- process of change in species composition over time as a result of abiotic and biotic agents of change
- unidirectional in communities
28
How does succession interact with agents of change
- agents of change can send an organism back successional stages
- if disturbance of stress is mild the community may not change as a whole and just affect individuals
29
What is primary sucession
- colonization of habitats devoid of life, can be slow because initial conditions are very inhospitable and first colonizers are usually stress tolerant
30
What is secondary succession
Occurs after a moderate disturbance over decades, involves reestablishment of a community in which most has been destroyed, soil must be undisturbed
31
Cowles theory
- space for time substitution, allows ecologist to predict successional patterns
- plants on the end of the shore represented pioneer plants
- further = pioneer then intermediate/climax community
32
Clements theory
- groups of species working together towards deterministic end
- succession is similar to development of an organism
- stable end point of climax community
33
Gleason
- communities are random product of fluctuating environmental conditions acting on individual species
- many different endpoints
- communities are not the predictable and repeatable result of interactions
34
Elton theory
- organisms and the environment interact to determine the direction of succession
- animals can affect the timing and sequence of sucession
35
What are the three models of succession?
Facilitation: early species change condition to make environment more suitable for next successional stages
Tolerance: Early successional species change local conditions, but these changes are neutral
Inhibition: Early successional species create conditions that inhibit species of the next stage, disturbance has to reduce pop of early species to get to next stage
36
What is hysteresis
The inability of a system to shift back to the original community state even after the original conditions have been restored
37
What are the spatial scales of species diversity
Global: latitude, continental drift, evolutionary time scale
Regional: smaller geographical areas, species limited by dispersal, rate of extinction and speciation (also called gamma, all 4 of those communities in chart)
Landscape: physical geography, emigration, immigration (beta diversity: change in species diversity over a landscape and different communities, = gamma/alpha)
Local: physical conditions, species interactions (alpha, richness within a single community in that landscape)
38
Local (alpha) and regional (gamma) processes that determine local species diversity
Slope = 1, all species in the region are also found in local communities
Slope < 1, local species determined by regional species pool, dispersal important
Slope = curve to plateau, local processes (species interactions, physical habitats, limited dispersal) determine local species richness
39
What did Wallace conclude
1. Earth’s landmass can be divided into six biogeographical regions that differ in species diversity and composition
2. There is gradient of species diversity with latitude, with greatest in topics and decreases at poles
- supported evolutionary theory of continental drift
40
Why is there greater species diversity with latitude (tropics)
1. Greater land mass in tropics = more species
2. Warmer and stable temp
3. Cradle and museum (more species evolved and stayed)
4. Trophic have higher NPP, solar energy captured in plant biomass, more trophic levels
41
Species-area relationship
- determine immigration and extinction rates
| - species richness increases with area sampled and decreases with distance
42
What does the curve of a species area curve represent
- plateau: sampling effort of area sampled increases, progressively fewer new species are encountered
- steeper slope: greater difference in richness among areas sampled
43
Regional species pool
- species richness of the entire region, passes through a set of filters to see who can live there
44
What are the filters of regional species pool
1. mobility (abiotic): move more = appear more in regional communities
2. Environmental conditions (abiotic): physical constraints that restrict movement
3. Species interactions (biotic): species that are dependent on other species, do not experience competitive exclusion
45
Biotic resistance
- interactions between native and non-native species that prevent the non-native species from establishing in a community
46
Resource partitioning
- driven by natural selection
| - competing species use limited resources in different ways to coexist
47
Hutchinson’s model for coexistence
```
Tc = time for one species to completely exclude another
Te = time for environmental variation to affect a population
```
48
What does gucci mane smell like
Ass and booty
49
What is the intermediate disturbance hypothesis
- explain how gradients in disturbances affect species diversity in a community
- highest levels of diversity found at intermediate level
- when levels of disturbance, stress or predation are low diversity is reduced by competitive exclusion
- when levels of xyz is high, diversity is reduced by local extinction
50
What is the lottery model
- emphasize the role of chance in maintaining species diversity
- species must have similar interaction strengths and growth rates and be able to respond quickly to disturbances
- ex. Fishy die, next fishy close to coral gets house
51
3 hypotheses that explain community diversity and community function
Complementary: linear, each species added to the community has an equal effect on community function. No overlaps and assumes equal strength and function
Redundancy: Non-linear, graphed as overlapping. Once species richness reaches a threshold, additional species are redundant. Assumes equal strength and function
Idiosyncratic: proposes that ecological functions of some species have stronger effects than others, dominant species have larger effect, keystone or foundational
52
Direct vs Indirect competition
- species compete indirectly by exploitation competition (bass and trout example)
- species compete directly by interference competition where they directly interfere with another animals food source
53
Competitive exclusion vs competitive coexistence
Exclusion: superior species prevents inferior species from accessing essential resources, potentially causing them to go locally extinct
Coexistence: the ability of species to coexist with one another despite sharing limited resources
54
What are two types of facilitation
Mutualism: mutually beneficial interactions between individuals of two species (+/+)
Commensalism: individuals of one species benefit, while the other does not but is not harmed (+/0)
55
What is symbiosis
- two species living in close physical contact
| - mutualism, commensalism, and parasitism
56
What is primary production
Chemical energy derived from the uptake of carbon during chemosynthesis (dark, feeds on chemosynthetic bacteria) and photosynthesis. Both store energy in the form of carbon dioxide bonds
57
What is Gross Primary Production (GPP)
Total amount of carbon taken up by plants or autotrophs in an ecosystem
58
What two factors influence GPP
1. Climate: precipitation and temperature: photosynthesis increases as temp increases but adequate water is necessary so a low GPP can be assumed in desert
2. Leaf area index (LAI): the amount of ground covered by leaves, ignores full leaf overlap. Due to shading the incremental gain in photosynthesis for each affect leaf layer decreases. Eventually, respiratory costs associated with adding lead layers outweigh the photosynthetic benefits.
59
What is Net Primary Production (NPP)
Energy remaining after respiratory losses
NPP = GPP-R
- May be allocated in plants for reproduction, storage, defence, or growth
60
How to estimate NPP in terrestrial ecosystem
| - limitations and solution
- harvest above ground biomass at the end of growing season
Bad:
- labour intensive
- you’d have to account for loss due to herbivory and disease
- only above ground measured, roots not
- destructive to ecosystems
- remote sensing light technique, compares different wavelengths of light (ex. 600-900nm chlorophyll content can be seen)
61
What is Net ecosystem exchange (NEE)
- direct measure of net CO2. The exchange of CO2 between the ecosystem and the atmosphere
NEE = GPP - (AR + HR)
62
How is NEE measured
- eddy covariance towers
| - co2 levels measured by sensors placed at different heights
63
What are the 3 components of NEE
1. The removal of carbon dioxide from atmosphere due to photosynthesis
2. Introduction of carbon dioxide into atmosphere via heterotrophs
3. IC and autotrophic respiration
64
What controls NPP in terrestrial environments
- controlled by climate
- precipitation: at low levels, plant production limited by reduced photosynthesis bc stomata closes to prevent water loss
at high levels of precipitation NPP decreases because more cloud cover reduces sunlight
- temp: NPP increases with temp, at low = reduced enzyme activity inhibits NPP and in dry stomata closes
ecosystem respiration (AR+HR) also varies with temperature
65
Respiration vs temp relationship
- respiration can increase in temp in autotrophs and heterotrophs
- respiration increases in low temp for homeothermic organisms
- high temp = high enzymatic activity
- too high temp = enzymes denature
66
How does nutrients affect NPP
- plants in resource poor conditions = slower intrinsic growth rate
67
What controls NPP in aquatic ecosystems (still water, flowing and ocean)
- nutrient availability
- addition of phosphorus to still water promotes Cyanobacteria to increase = fish die bc bacteria consumed all the oxygen
- that is why we don’t use in shit that will go into waterways
- in flowing water nutrients supplied via distribution of organic matter from dead organisms
- in northern ocean limited by N and in southern limited by Fe
68
What limits NPP in aquatic ecosystems
- nitrogen, phosphorus, and turbidity
- wind and water currents bring sediments into the water column, increasing turbidity (cloudiness), reducing the amount of solar radiation available to phytoplankton
69
Autochthonous
Energy produced by autotrophs within the system
| - often lower quality
70
Trophic efficiency
The amount of energy at one trophic level divided by the amount of energy at the trophic level immediately below
71
Consumption efficiency
The proportion of available biomass ingested, higher for carnivores
72
Assimilation efficiency
Proportion of ingested food that is assimilated, higher for carnivores bc plants have shit like cellulose that cannot be easily digested
73
Bottom up vs Top down control
Bottom up: energy flow through the ecosystem is determined primarily by the supply of resources limiting NPP. Greater availability = increased NPP
Top down: energy flow through an ecosystem is determined primarily by rates of consumption at the highest trophic levels which influence abundance’s and species composition at multiple levels below
74
Trophic cascade
Series of changes in abundance and species composition of non consumptive species interactions
75
What is chemical weathering
Chemical reactions release soluble forms of the mineral elements
76
What is the cation exchange capacity
- the ability of a soil to hold and exchange cations, related to the amount and types of clay particles present
77
What are two atmospheric sources of nutrients
1. Nitrogen fixation
| 2. Aerosols/atmospheric decomposition
78
What is litter and how is it used
- litter is fresh undecomposed organic matter on the soils surface
- animals like earth worms, termites and nematodes consume litter and break it up into progressively finer particles, this facilitates chemical breakdown
79
Mineralization
Chemical conversion of organic matter into inorganic nutrients
80
What is lignin, what does it inhibit
- lignin strengthens plant cell walls and is difficult to decompose
- inhibits decomposition, except in desert bc abiotic photodegradation = higher mass loss bc lignin is vulnerable)
- higher lignin:N ratio = harder to break down
81
Nitrification
NH3 and NH4+ are converted to NO3- by chemoautotrophic bacteria in aerobic conditions
82
Denitrification
Some bacteria use NO3- as an electron acceptor converting into N2 and N2O in anoxic conditions (soil fertility estimated from conc. Of inorganic forms of nitrogen)
83
How to quantify rates of nutrient cycling
Estimate:
Pools- total amount of a nutrient in a component of the ecosystem
Mean residence time- amount of time on average that molecule spends in the pool
= total pool of element/rate of input
84
How to calculate nutrient losses in terrestrial ecosystem
In catchment, quantify by measuring dissolved and particulate matter in stream water
85
How to calculate total amount of element entering the catchment
Conc of element x volume of precipitation received in catchment
86
What limits primary production and community composition in early stages
Nitrogen availability, because there is little organic matter in soil and little nitrogen from decomposition
87
What becomes limiting in later successional stages
- phosphorus, P becomes exhausted over time and decomposition becomes more important
- soluble P may combine with iron, calcium, or aluminium to form insoluble compounds that are unavailable as nutrients (occlusion)
88
What is limiting during intermediate stages
Both N and P
89
What are the primary threats to biodiversity
Habitat loss, invasive species, over exploitation, pollution, disease and climate change
90
Taxonomic homogenization
The spread of non-native and native generalists, coupled with declining abundance and distributions of native specialists
91
Define landscape
An area that is spatially heterogeneous in one or more features of the environment; a landscape typically includes multiple ecosystems
92
Why might some species flourish under habitat fragmentation
- during habitat fragmentation some species go extinct, but others can flourish due to changed condition
- ex. Maybe this lacks top predators
93
Edge effect
Abiotic and biotic changes associated with habitat boundaries. Change in physical environment over a certain distance into the remaining fragment and change biological interactions and ecological processes
94
Best configurations for core natural area
1. Reserve size, bigger is better
2. Number of reserves, one is better than a few small
3. Reserve proximity, several reserves close together are better than several apart
4. Reserve connectivity, habitat corridor: narrow patches that connect blocks of habitat
5. Reserve shape, minimizes edge effects compound shapes are best
6. Buffer areas, buffer zone: large areas with less stringent controls on land use and are at least partially comparable with resource requirements
95
Character displacement
Competition causes the phenotypes of competing species to evolve to become different overtime, facilitating resource partitioning
96
When can coexistance not occur
Dominant competitor is unable to reach its own carrying capacity, coexistance will be maintained
97
Vicariance
Evolutionary separation of species by barriers (like continental drift)
98
Climate envelope
Describe relationships between species occurrences and bio climate variables (temp and precipitation) to define a niche
99
Equilibrium theory of island biogeography
Number of species on an island depends on a balance between immigration or dispersal rates and extinction rates
100
Eutrophication
Lots of nutrients that increase the biomass a lot (ex farming runoff)
101
Oligotrophic
Nutrient poor lake with low primary productivity
102
3 stages of decomposition in terrestrial ecosystems
1. Fragmentation - animals living in the soil break the litter into progressively smaller fragments increasing surface area
2. Mineralization - bacteria and fungi release enzymes that act on the exposed surfaces of the fragments to convert organic macromolecules into soluble nutrients
3. Uptake - small organic compounds and inorganic nutrients are released into the soil solution, then can be taken up by plants and microorganisms
103
Species diversification rate
The tropics have the most land area on earth and stable temperatures, large thermally stable areas should decrease extinction rates
104
Species diversification time
Tropics are more climatically stable over time and species have had more time to evolve, temperate and polar regions have undergone severe climatic changes, disrupting diversification
105
Productivity/carrying capacity
Highest productivity in tropics, promotes larger sizes because carrying capacity is larger. Higher productivity leads to lower extinction rates, greater coexistence and overall higher species richness
106
4 general features of competition
1. Competition may compete directly or indirectly
2. Competition can vary in intensity (low or high food availability)
3. Competition is often asymmetrical (unequal division of resources amongst competitors)
4. Competition can occur between closely or distantly related species
107
Rates of extinction are difficult to measure because…
The number of species on earth is currently unknown
108
What is a patch
Homogenous unit within a landscape
109
Matrix
Greatest area in the landscape, high degree of connectivity, dominant role in ecosystem dynamics
110
What are biotic and abiotic factors that make ecosystems dynamic
Abiotic: flow of water, energy, nutrients, or pollutants
Biotic: animals, seeds, pollen
- patches must be connected, or the surrounding habitat (matrix) must be suitable for dispersal
111
Fragmentation leads to…
Loss of top predators, giving rise to cascading effects
112
Why is earth warming
Anthropogenic emissions of greenhouse gases (carbon dioxide, nitrous oxide and methane)
113
What is climate change
Directional change in climate over a period of at least 3 decades
114
What does anthropogenic (pollution from humans) release of C to atmosphere from terrestrial pool result in
Land use change, mostly deforestation (20%) and from burning fossil fuels (80%)
115
What is ocean acidification
Atmospheric CO2 affects ocean pH by dissusing in and forming carbonic acid
