Exam 5/6 Flashcards
(179 cards)
1
Q
what is a community?
A
association of interacting populations defined by the nature of their interactions or the place in which they live. boundaries are not rigid and often artificially defined for researcher purposes.
research approach: diversity and relative abundance of species living together or species interactions (predation)
2
Q
what does the zones in which species grows reflect?
A
-different tolerance ranges for various environmental conditions
-ability to compete with other species
(ex: intertidal zones w/ barnacles)
3
Q
communities are categorized by their dominant __________ or by _________ __________ that affect the distribution of species
A
organisms
physical conditions
4
Q
what was Frederick Clements view on communities?
A
-interdependent communities
-communities are superorganisms
-species tightly bound together in common coevolutionary history
-a community will always reach a stable climax state
5
Q
what are interdependent communities?
A
communities in which species depend on each other to exist
6
Q
what is ecotone?
A
a boundary created by sharp changes in environmental conditions over a relatively short distance, accompanied by a major change in the composition of species
7
Q
what was Henry Gleason’s view on communities?
A
-independent communities
-community consists of individual species that respond independently and gradually to fluctuating environmental conditions
-species, not communities, are the essential unit (individualistic)
8
Q
what are independent communities?
A
communities in which species do not depend on each other to survive
9
Q
Robert Whittaker supported the ______________ community hypothesis and ___________ _________ helped bring closure to the Clements-Gleason debate. different tree species appeared and disappeared at different ___________, corresponding to changes in moisture
A
independent
gradient analyses
elevations
10
Q
what is species richness?
A
the number of species in a community (area)
11
Q
what is relative abundance (evenness)?
A
the proportion of individuals in a community represented by each species
12
Q
in a typical community, only a few species have low or high abundance; most species have ______________ abundance
A
intermediate
13
Q
what is log-normal distribution?
A
a normal, or bell-shaped distribution that uses a logarithmic scale on the x-axis
14
Q
what are rank abundance curves?
A
graphed curve that shows species evenness (y-axis) and species richness (x-axis)
15
Q
what is species diversity?
A
number of species in an area and their relative abundance (evenness)
16
Q
what is alpha (local) diversity (a)?
A
average diversity (evenness and number) of species in a habitat or local area
17
Q
what is beta (turnover) diversity (B)?
A
difference in species among habitats
18
Q
what is gamma (regional) diversity (y)?
A
number of species in all of the habitats that comprise a large geographic area (usually not used in research)
19
Q
species richness often __________ from the local to landscape scale because habitat ________ increases along this gradient
A
increases
diversity
20
Q
what are species accumulation curves?
A
allow comparisons across habitat or experimental treatments. high variation among habitats (each curve) x-axis: number of individuals collected
y-axis: number of species discovered
21
Q
what are species area curves? what is the equation for species?
A
number of species increases with area sampled
(slope is always increasing; species richness increases with area sampled)
S = cA^z
S = species
A = area
z = constant; slope of the species area relationship in log-log space
c = constant; the number of species that would exist if the habitat area was confined to one square unit
-log S = log c + z log A
22
Q
what are 3 different regional diversity categories?
A
-north-south: increasing richness with increasing temperature
-east-west: increasing richness with increasing habitat heterogeneity
-dispersal limitation: lower richness with increasing distance from mainland species pool
23
Q
species diversity can be limited by either __________ (northern hemisphere) or by __________ (southern hemisphere)
A
energy
water
24
Q
temperatures vary _______ in the Northern hemisphere where the moderating influence of _______ is less (global temperature patterns driven by solar radiation)
A
more
water
25
the species richness of a community can be affected by the amount of _________ ___________. to understand the influence of ________, ecologists have examined the relationship between productivity and species richness and found a wide range of patterns (U-shaped, negative, neutral, positive and hump-shaped correlations)
available resources
resources
26
what shaped curve is the most common observed relationship between diversity and productivity?
hump-shaped curve: sites with medium productivity have higher species richness than sites with low or high productivity
27
what are keystone species?
a species that substantially affects the structure of communities, although it may not be particularly numerous. remove of keystone species can cause a community to collapse. (ex: predatory sea stars)
28
habitats with simple vegetation structure tend to have _______ species than more complex habitat with similar productivity levels
fewer
29
what is a food chain?
a linear representation of how different species in a community feed on each other
30
what is a food web?
a complex and realistic representation of how species feed on each other in a community (arrows in a food web represent consumption)
31
what is bottom-up control?
when the abundances of trophic groups are determined by the amount of energy available from producers
32
what is top-down control?
when the abundance of trophic groups is determined by the existence of predators at the top of the food web
33
provide an example of both top-down and bottom-up control in a lake ecosystem
in lakes, bottom-up control occurs when an increase in phytoplankton causes an increase in the abundance of lower trophic levels. top-dwelling control occurs when an increase in large fish causes a decrease in small fish, an increase in zooplankton and a decrease in phytoplankton
34
predators and plants are (mostly) _________ ___________ (bottom-up)
herbivores are (mostly) regulated by their __________ (top-down)
predators regulate herbivores and benefit plant abundance (__________ __________)
resource-limited
predators
trophic cascade
35
provide an example of a trophic cascade in Yellowstone
Yellowstone wolves are a keystone species, and their removal caused a large trophic cascade. when wolves were reintroduced into the population, elk populations decreased, beaver population increased, bison population increased, browsing decreased and aspen tree height increased
36
what are ecosystem engineers?
keystone species that affect communities by influencing the structure of a habitat (ex: beavers build dams in streams that cause large ponds to develop; because the stream is converted to a non-flowing pond a different community of plants and animals colonize and persist in beaver ponds)
37
what is succession?
the process of the change in species composition over time (predictable series of species replacement (seres) over time)
38
describe the colonization of species through succession
bare rock --> lichens, mosses --> herbs, weeds, grasses --> shrubs, pines, hickories, immature oaks --> oaks, hickories, black walnuts, maples, beeches ("climax communities")
39
what is primary succession?
the establishment and development of communities in newly formed habitat that was previously devoid of organic matter
40
what are pioneer species?
the earliest species to arrive at a site; typically able to disperse long distances and arrive quickly at disturbed sites
41
provide an example of primary succession
Mt. St. Helen--May 18, 1980-- caused 230 sq miles of forest flattened. after the event occured, the number of species declined significantly but then after 2/3 years, plant species began to increase again. the land took 10 years to have the first plant (knotweed) inhabit. later lupine, firs and pines came to inhabit.
42
during succession, what does species richness do?
species richness increases rapidly at first, followed by a plateau and a small decline. this pattern is consistent across most cases of succession
43
what is secondary succession?
the development or regeneration of communities in disturbed habitats that contain no plants but still contain organic soils (tornado, fire, hurricane causing gaps in forest, agricultural abandonment)
44
what is an example of secondary succession?
Yellowstone fires (1988) -- 36% of Yellowstone was burned, and average depth soil char = 1/2 inch, but most plants re-sprouted
45
how does succession relate to animals?
changes in the plant community can change the habitats that are available to animals, which causes changes in the animal community
46
what are the two main ways of thinking about why//how succession progresses
1. direct species interactions: tolerance, inhibition, facilitation
2. life history tradeoffs: dispersal, growth, survival, and reproduction
47
early vs. late succession species have differing ______ that result from a _____________ of high dispersal, rapid growth, and early reproduction with enhanced competitive ability
traits
tradeoffs
48
what does it mean to self-inhibit?
occurs when a plant is shade intolerant and it grows too abundant and causes too much shade for its own success (ex: horseweed)
49
what is facilitation?
each sere paves the way for the next by providing conditions that increase probability of colonization
50
what is an example of long-term succession
Glacier Bay Alaska--retreating since 1774.
1. pioneers (lichens)
2. shrubs (Dyras)
3. small trees (alders)
4. large trees (spruce)
51
describe facilitation in terms of Glacier Bay Alaska
lichens and liverworts create conditions that retain soil moisture and add organic matter which allows for shrub growth. alder trees fix nitrogen through mutualism with root bacteria and this increased nitrogen availability in soils allows for colonization by hemlocks and spruce, but dispersal limitation plays a role in spruce establishment
52
an analysis of tree rings in a ____________ found that spruce trees rapidly colonized older sites but not younger sites which suggests that soils in older and younger sites may not have experience the _______ _________ through succession
chronosequence
same changes
53
what are the best approaches to analyzing succession?
use a combination of methods:
-chronosequences
-pollen records
-long-term studies of a single site
54
what is resistance (constancy)?
the capacity of an ecological system to resist external perturbation
-the amount of a community changes when acted upon by a disturbance (+/- of a species)
55
what is resilience?
the ability for an ecological system to return to a reference state after a disturbance
56
what are 3 US legislation examples of resilience?
1. Environmental planning and assessment act 1979
2. Threatened species conservation act 1995
3. Protection of the environment (operations) act 1997
57
what matters in the ball-in-cup model?
-location of ball
-depth of cup
-breadth of cup (how broad is the cup)
-tipping point/threshold crossed = alternate stable state (regime shifts)
58
provide an example of the ball-in-cup model?
coral dominated reefs have experienced a regime shift (crossed the threshold) due to overfishing, coastal eutrophication, disease, bleaching, and warming temperatures and has resulted in algae dominated reefs and coral die-offs
59
__________ ____________ is not an end point, more so communities tend towards equilibrium and most often exist in a __________ ___________ _________
climax community
dynamic steady state (responding to environmental variation)
60
for ecological restoration to occur, what do you need to understand and consider?
need to understand: scale (ecosystem, habitat, focal species), ecological succession, natural distribution regimes, and natural range of variability
considerations: risks, economic goals/conflicts/competing interests
61
what is one thing that ecologists can do in order to reduce the risk of megafires?
prescribed burning and regular fire regimes in order to reduce fuel load
62
what is an ecosystem? what is the research approach?
assemblage of communities of biotic organisms along with their (abiotic) physical and chemical environment. research approach: energy flow and nutrient cycling through organisms and their physical environment. element pools: carbon, oxygen, nitrogen, hydrogen, and phosphorus
63
ecological systems obey which physical and biological laws?
1. law of conservation of matter
2. first law of thermodynamics (energy conservation)
3. dynamic steady state
64
mass and energy are lost to the ___________, stored (unavailable) in _______, and is recycled within the __________
atmosphere
soils
biosphere
65
photosynthesis is not a very ________ process, only __% of solar energy is captured by photosynthesis--this is gross primary productivity
efficient
1% (90% of solar energy is reflected or not absorbed by plants)
66
what is primary productivity?
the rate at which solar or chemical energy is captured and converted into chemical bonds by photosynthesis or chemosynthesis
67
what is gross primary productivity (GPP)?
the rate at which energy is captured and assimilated by producers in an area
68
what is net primary productivity (NPP)?
the rate of energy that is assimilated by producers and converted into producer biomass in an area; includes all energy that is not respired.
69
what does NPP equal (formula)?
NPP = GPP - respiration (units of J/m^2/ year)
(GPP = NPP + respiration)
70
describe light/dark bottle experiments in terms of NPP and GPP
when a leaf is exposed to light in a chamber, both photosynthesis and respiration occur, the net uptake of CO2 represents NPP. when a leaf is concealed in the dark, only CO2 respiration occurs. you can then calculate the GPP.
71
what are methods for measuring primary productivity (NPP) in small areas?
-change in producer biomass over time (harvesting aboveground biomass; belowground often ignored = reduced estimates)
-"label" leaves with rare carbon isotope (C14), track the net movement of C14 from the air into the plant and back into the air
72
what are methods for measuring primary productivity (NPP) in large areas?
-flux towers sample CO2 concentrations at different heights (vertical measurement)
-remove sensing of chlorophyll; high green light reflectance indicates high vegetation cover
73
what did neon (national ecological observatory network) observations find?
mesquite trees have a much higher % of foliar nitrogen compared to grasses
74
productivity and __________ are highly correlated
biodiversity
75
NPP varies with ________ and across terrestrial and aquatic biomes. what type of biomes have very high NPP?
latitude
terrestrial: tropical rainforests + tropical seasonal forest + temperate rainforests
aquatic: swamps and marshes + coral reefs + salt marshes
76
what factors affect primary productivity?
light (energy), temperature, water and nutrients
77
light influences primary productivity: at the ___________ point, photosynthesis balances respiration and beyond the ___________ point, photosynthesis no longer increases with increasing light intensity
compensation
saturation
78
how does temperature affect primary productivity?
with an increase in average temperature, there is an increase in NPP (slightly exponential)
cold temperatures have low NPP
79
primary production increases with precipitation up to _________ per year but declines at higher precipitation rates. why?
~3m (3,000mm)
this is because too much water causes the soil to be saturated and this decreases aeration and causes nitrogen limitations because soil organisms cannot function properly
80
what nutrients have a strong effect on NPP in terrestrial ecosystems?
nitrogen and phosphorus
-grasslands, forests, and tundra habitats all experience increased NPP when N and P were added
81
in the ocean, _____ is limiting because it rapidly reacts with phosphorus and precipitates to the ocean floor. what was proposed to fix this problem?
iron
to fix this iron limitation, it was proposed to just add a bunch of iron over 64 square km of ocean which would triple phytoplankton numbers, and was suggested to grow algae and reduce CO2 in both the air and ocean (geoengineering marine systems)
82
what are potential positive and negative outcomes of geoengineering marine systems?
positives:
-draw down carbon dioxide from atmosphere
-sequester carbon in deep sea sediment
negatives:
-deplete nutrients that support food webs
-create zooplankton blooms; increased CO2 respiration = zero net C sequestration
-create algal blooms = deplete O2 in ocean
83
nutrients cycle through (bodies of organisms in) ecosystems and exist in different _________ states carrying different amounts of ________
chemical
energy
84
what are macronutrients and micronutrients?
macronutrients: C, H, O, N, P, K, [Ca, S]
micronutrients: Na, Cl, Mn, Mg, B, Bu, Fe, Co, Cu, Mo, Zn
85
what does primary production (photosynthesis) determine?
1. number of trophic levels
2. herbivore and predator abundance
86
bottom-up trophic cascade: ___-___% of energy is loss as it is transferred up the trophic chain; ___% conversion efficiency- organic matter stored
80-90%
10%
87
what are primary producers in aquatic ecosystems versus terrestrial ecosystems?
aquatic: phytoplankton + cyanobacteria (easy to consume, low investment in structure and chemical defenses)
terrestrial: gymnosperms + angiosperms (high investment in structure: hemicellulose, lignin, and chemical defenses)
88
in terrestrial systems, pyramids of biomass and energy look _________
(high plant longevity and defenses = _______ consumption)
similar
low
89
in aquatic systems, pyramids of biomass and energy are ______________
(low plant (algae) longevity and defenses = ________ consumption)
inverted
high
90
what is energy residence time?
the length of time that energy spends in a given trophic level; the longer the residence time, the greater the accumulation of energy in that trophic level.
91
what does energy residence time equal (formula)?
energy residence time (years) = energy present in a trophic level (J/m^2) / net productivity (J/m^2/year)
92
average residence times for primary producers range from more than ____ ______ in forests, to less than ___ _________ in aquatic ecosystems
20 years
20 days
93
what is biomass residence time?
the length of time that biomass spends in a given trophic level
94
what does biomass residence time equal (formula)?
biomass residence time (years) = biomass present in trophic level / net productivity
95
what is consumption efficiency?
the percentage of energy or biomass in a trophic level that is consumed by the next higher trophic level
96
what does consumption efficiency equal (formula)?
consumption efficiency = consumed energy / net production energy of the next lower trophic level (J)
97
what is assimilation efficiency?
the percentage of consumed energy that is assimilated into flesh
98
what does assimilation efficiency equal (formula)?
assimilation efficiency = assimilated energy / consumed energy (J)
99
assimilation efficiency varies among trophic levels; primary consumers tend to have ______ efficiencies than secondary consumers because prey tissues are more digestible than plant tissues.
lower
100
describe trophic dynamics
movement of carbon, nutrients, and energy among organisms in an ecosystem (eating)
net primary production --> ingestion --> assimilation (along with excretion and respiration) --> production --> growth, storage and reproduction (energy available to the next trophic level)
101
____________ is taking inorganic forms and converting them into organic forms (ex: photosynthesis)
assimilation
102
_______________ is taking organic forms and converting them into inorganic forms (ex: respiration, leaching, excretion)
dissimilation
103
what are the four major categories of ecosystem services?
1. Regulating services (climate regulation, water quality)
2. Provisioning services (food, water, fuel)
3. Cultural services (recreation, spiritual beliefs)
4. Supporting services (ecosystem dynamics, disturbance cycles)
104
industries based on ____________ ____________ are the mainstay of economies… ___________ labor force accounts for 22% of the worlds population and half of the total labor force. Ecosystem service industries such as food production, marine fisheries, timber industry, marine aquaculture, and recreational fishing/hunting have a vast economic value
ecosystem services
agricultural
105
describe the hydrologic cycle
movement of water through ecosystems and atmosphere; includes evaporation, transpiration (water loss through plant leaves) and precipitation
106
how do humans affect the hydrologic cycle?
-increased runoff and erosion due to increased cement coverage (less soil surface to allow for water percolation)
-increased cyclones and hurricanes intensity and frequency
-changes in monsoon seasonality
-decreased water quality due to increased runoff, eutrophication and algal blooms (increased neurotoxins)
107
generally, describe 3 components of the carbon cycle
1. Assimilation and dissimilation reactions
2. Ocean-atmosphere and ocean-land CO2 exchange
3. CO3 (carbonate) precipitation in oceans
108
what are the two major human derived sources that play into the carbon cycle?
1. use of fossil fuels (88%)
2. deforestation and use of timber resources (12%)
109
what are the major pools/sink for carbon?
-oceans
-soils and plant vegetation
-atmosphere
110
what are three dominant examples of consequences of climate warming in the carbon cycle?
1. drought induced forest die-off (warming and drying during growing seasons that leads to plant death along with increased wildfire risk)
2. ocean acidification (excess CO2 in oceans causes the pH to decrease and the availability of carbonates decreases and restricts numerous oceanic organisms that need carbonate to survive)
3. permafrost thaw (release of highly acidic carbon and methane from deep soil sediments that took millennia to form due to the permafrost layer on top melting)
111
current atmospheric CO2 levels fluctuate, but are ____ ________ than the maximum concentration during the past 400,000 years (measured via ancient ice cores)
31% higher
112
describe the importance of nitrogen
-nitrogen is required by all organisms for growth
-N often limits primary productivity
-excess N can cause toxic plant/algae growth (eutrophication)
113
atmospheric N2 is _____ __________ and the amount of fixed N is ____________
not bioavailable
increasing
114
inorganic N2 enters ecosystems through ___________ and leaves through ________________
fixation
denitrification
115
describe how nitrogen leaves the cycle
denitrification: occurs in very water logged soils, nitrate and nitrite get converted into nitrous oxide by denitrifying bacteria which then gets converted into N2 gas (atmospheric nitrogen)
116
generally, how does nitrogen enter ecosystems?
atmospheric nitrogen is converted into ammonium
biotic: nitrogen fixation via Cyanobacteria and some bacteria associated with plant roots (rhizobia)
abiotic: lightning, combustion (Haber Bosch), and fertilizer production
117
what are some consequences of having excess nitrogen?
Deposition (both dry (particles/gases) and wet (rain/snow))
-decreased plant biodiversity
-changes in soil nutrient cycling
-lakes/streams acidification or eutrophication
118
how is phosphorus made available to humans?
weathering or mining processes
119
in what ways have humans changed the phosphorus cycle?
-cultivate crops with P based fertilizers
-farming (especially hog farms) result in runoff and the P gets leached into our water streams and can cause harmful algal blooms
-cleaning detergents are also P based
120
what is state factor theory?
theory that helps us understand key components or elements of ecosystem processes which are:
1. parent materials
2. climate
3. topography
4. potential biota
5. time
121
where does the state factor theory stem from?
soil formation processes (Jenny equation: Soil = f(Cl, O, R, P, T)
122
how can weathering rates be measured?
by measuring the rates that nutrients both enter and exit a system
123
what are inputs and outputs of nutrients?
inputs: precipitation, particulates, weathering of bedrock
outputs: leaching and runoff
124
what is decomposition?
the breakdown of dead, complex organic matter that formed during the construction of plant and animal tissue via leaching, fragmentation, and chemical alteration into simple organic and inorganic molecules available for microbial and plant uptake.
-made possible by detritivores
125
trees began producing bark (lignin) at the beginning of the ____________ period (360 million years ago) but fungi did not evolve the ability to digest lignin for 50 million years, this non-decaying wood was buried and became _______
carboniferous
coal
126
human metabolism is embedded within ____________ metabolism
planetary
energy flow through our metabolism describes our ability to change the world around us
127
what is landscape ecology?
the field of study that considers the spatial arrangement of habitats at different scales and examines how they influence individuals, populations, communities, and ecosystems
128
what are the types of species diversity?
alpha (local) diversity
beta (turnover) diversity
gamma (regional) diversity
129
current habitat heterogeneity is a reflection of _______ and ___________ events caused by natural and human forces
recent and historical
-natural variation in topography = habitat heterogeneity
humans act as ecosystem engineers by constructing buildings, dams, irrigation channels
130
throughout the 20th century, natural fires were suppressed in Yellowstone National Park. in 1988, hundreds of fires were ignited by human activity and natural forces (lightning). what do the patterns of burning depend on?
the patterns of burning depended on landscape characteristics (wind patterns and amount of plant litter)
131
how long did it take for the Maya civilization to collapse? what caused this collapse?
the civilization disappeared in less than 200 years.
25-40% reduction in rainfall caused this collapse (sandy soils are prominent in this area)
132
species ________ increases with area sampled
richness
133
what factors affect habitat fragmentation?
-habitat size
-quality of matrix
-habitat corridors
-fragment edges
134
fragmentation causes an increase in the amount of ________ ___________ compared to the original unfragmented habitat
edge habitat
135
an increase in edge habitat changes the _________ conditions and the _________ composition of a habitat
abiotic (ground temperature in a forest)
species
136
what is an example of habitat fragmentation?
only a small fraction of the Atlantic Forest along the Brazilian coast remains after decades of intense deforestation. deforestation has endangered endemic species (golden lion tamarin)
137
the destruction and degradation of habitat has been the largest cause of ____________ ____________
declining biodiversity
138
what type of pattern emerges from habitat fragmentation?
fishbone pattern of deforestation due to road access
139
what are metapopulations?
patches of suitable habitat support sub-populations embedded within a habitat matrix of unsuitable habitat.
-patch size and isolation influence probability of population occupancy
-sink patch = low quality
-source patch = high quality
140
what is the theory of island biogeography?
hypothesis: species richness is determined by both island area and isolation
141
MacArthur and Wilson found that species richness increases with island area and that islands closer to the mainland appeared to receive more __________ ________
colonizing species.
they measured bird species richness on 25 islands in the South Pacific and larger islands contained more species. among islands of similar sizes, near islands contained more bird species than far islands.
142
in Southwestern U.S. 26 species of mammals prefer to live in the mountaintop habitats. more species were found on _________ and less ________ mountaintops.
larger and less isolated
143
what is an example of an experiment conducted to evaluate the theory of island biogeography?
Daniel Simberloff and E. O. Wilson conducted a manipulative experiment to test effects of habitat size and isolation. On a set of islands in the Florida Keys,
they observed that islands closer to the mainland had more insect species than islands farther from the mainland. They built tents over selected islands,
and fumigated them to kill all insects. They removed the tents and allowed species to naturally recolonize.
They found that more insects recolonized islands closer to the mainland, and species richness of islands
was similar to values before fumigation.
144
what is the equilibrium theory of island biogeography?
the number of species on an island reflects a balance between the colonization of new species and the extinction of existing species
145
assuming the species pool of potential colonizers is a fixed size, then the rate of new species colonizing the island _________ as a function of how many species have already colonized the island
declines
146
As more species colonize the island, more species are subject to possible _________ due to chance and negative interactions (e.g. competition, predation, parasitism)
extinction
147
given that the island continues to experience colonization and extinction of species, these
opposing forces should result in an ________ ________of species richness on the island Ŝ.
equilibrium point
-this model only predicts the number of species at equilibrium, not the species composition at equilibrium
148
at ____________, there is a continuous turnover of species, resulting in a temporally variable species composition
equilibrium
149
smaller islands should have ____________ extinction rates. islands nearer to a source habitat should have ________ ____________ rates
higher
higher colonization
150
what do habitat reserves do?
-set aside land for the primary purpose of conserving one or more species
-nature reserves are typically a compromise among various options
151
describe why active management is necessary
-historical disruptions (fire suppression, introduced species)
-external influences (things that happen outside reserve that influence dynamics)
-genetic drift (random mutations)
152
what are better habitat reserve management designs?
-larger reserve size
-larger rather than smaller
-closer reserve proximity
-square shaped reserve proximity
-greater reserve connectivity
-circular reserve shape
153
what are the patterns of diversity?
patterns of diversity exist at the global scales (total species richness is the highest near the tropics and declines toward the poles)
-latitudinal trends in diversity are pervasive and extend even to the oceans
-in the northern hemisphere, species richness of most animal and plant groups increases from north to south
-mammal species richness also increases to the west, likely due to the habitat heterogeneity of mountains
154
oceans have increased species richness at _________ latitudes
lower
ex: Researchers compiled records of marine organisms around the world and found that the highest marine diversity occurred in the tropics (i.e., Central America, southeast Asia) whereas the lowest diversity occurred near the poles
155
current distribution and abundance of a species is determined by __________ __________ of its ancestors
ecological experiences
156
what is convergent evolution?
species descended from unrelated ancestors are similar because they have evolved under similar selective forces
157
species richness correlates with what?
-latitude
-productivity (temp and precipitation)
-habitat heterogeneity and size
158
what mechanisms contribute to origin and maintenance of diversity?
-environmental variation / niche differentiation
-intermediate disturbance hypothesis
-pest Pressure negative density dependence
-random ecological drift (neutral theory)
159
drylands are expected to expand by ___-___% by 2099
11-23%
160
drylands store ____ of the above and ____ of the belowground terrestrial (vegetative) carbon
22%
38%
161
what drives vegetation in drylands?
rainfall patterns and elevation
in Tucson, summer storms can be quite intense
in California, there is no rain in the summer
162
dense, tall vegetation is widely regarded as a powerful tool to combat climate change as it is the _______ climate mitigation strategy
maximum
163
what are the predicted vegetation transitions?
-sparser systems
-lower growth forms
-lower productivity
-reduced longevity
-more pulse-driven vegetation
-faster turnover
164
under favorable rainfall patterns, woody vegetation in drylands will _________ more than herbaceous species
(carbon storage potential could be considerable)
benefit
165
what do we need to do in order to enhance predictive capacity?
-vegetation modelling
-remote sensing
-ground observations
166
what are the main models for climate-based solutions?
-DGNM's (broadly applicable, little input, coarse)
-ecophysiological models (local, detailed input required, precise)
-tree-centric models: intermediate complexity and manageable input
167
what two aspects do we need to consider when scaling ecosystem structure and productivity?
-spatial information
-temporal information
(spatiotemporal information)
168
what are the largest 5 mass extinctions in Earth's history?
1. end Ordovician: 60% terrestrial and marine life worldwide
2. 360 MYA (late Devonian): 13-million-year-old reefs died
3. end Permian: 80–95% of marine species extinct, reefs didn't reappear for ~10 MY
4. end Triassic: half of all marine invertebrates, 80% of all land animals
5. 65 MYA (end Cretaceous): virtually no large land animals survived (dinosaurs), major plant and marine extinctions
169
what are the main current problems were facing during the "6th mass extinction"
-Climate Change
-Biodiversity decline
-Pollinator decline
-Sustainable agriculture
-Emerging pathogens
-Antibiotic resistance
170
how many life forms exist in our biosphere?
we don't know but likely >90% have not been described
-8.7 million plants, invertebrates, vertebrates
-6 million fungi
-10,000-1 billion bacteria/archaea
171
genetic diversity describes the level of genetic ________ within a population
variation
172
species or functional diversity describes the __________ and __________ of species in a community
number and evenness
173
ecosystem diversity describes the diversity of ___________ that maintain species and genetic diversity
environments
174
how many biodiversity hotspots are there and what are the two strict criteria for biodiversity hotspots?
34 biodiversity hotspots
1. >1,500 endemic vascular plants
2. <30% of its original natural vegetation
175
__________ hosts two of the world's biodiversity hotspots
Columbia
Tropical Andes Region
Choco/Darién Region
176
the 34 biodiversity hotspots cover _____ of Earth’s surface, _____ of endemic terrestrial vertebrate (bird, mammal, reptile, amphibian) species and ____ of endemic terrestrial plant species
2.3%
42%
50%
177
by protecting hotspots, governments are able to protect a ________ __________ of species
larger number
178
Sustainable development “meets the needs of the present without _________ the ability of future generations to meet their own needs.”
compromising
179
