Species interactions are the backbone of
communities.
communities.
Species interactions
both species are harmed, multiple organisms seek the same limited
resources
– Food, space, water, shelter, mates, sunlight
resources
– Food, space, water, shelter, mates, sunlight
Competition
one species benefits and the other is
harmed
• Predation, parasitism, and herbivory
harmed
• Predation, parasitism, and herbivory
Exploitative
both species benefit
Mutualism
Competition among members of the same
species.
High population density = increased competition
species.
High population density = increased competition
Intraspecific
Competition between members of different
species.
Leads to competitive exclusion or species coexistence
Territoriality – Defending resource-rich area, primarily against members of own species.
– Resource Allocation and Spacing
species.
Leads to competitive exclusion or species coexistence
Territoriality – Defending resource-rich area, primarily against members of own species.
– Resource Allocation and Spacing
Interspecific
one species completely
excludes another species from using the resource
Zebra mussels displaced native mussels in the Great Lakes
excludes another species from using the resource
Zebra mussels displaced native mussels in the Great Lakes
Competitive exclusion
neither species fully excludes the
other from resources, so both live side by side
This produces a stable point of equilibrium, with stable
population sizes
Species adjust to minimize competition by using only a
part of the available resource (niche)
other from resources, so both live side by side
This produces a stable point of equilibrium, with stable
population sizes
Species adjust to minimize competition by using only a
part of the available resource (niche)
Species coexistence
when an individual fulfills
its entire role by using all the available resources
its entire role by using all the available resources
Fundamental niche
the portion of the fundamental
niche that is actually filled
niche that is actually filled
Realized niche
when species divide
shared resources by
specializing in different
ways
– Ex: one species is active
at night, another in the
daytime
– Ex: one species eats
small seeds, another
eats large seeds
shared resources by
specializing in different
ways
– Ex: one species is active
at night, another in the
daytime
– Ex: one species eats
small seeds, another
eats large seeds
Resource partitioning
competing species evolve
physical characteristics that reflect their reliance on the
portion of the resource they use
– Ex: birds that eat larger seeds evolve larger bills
– Ex: birds that eat smaller seeds evolve smaller bills
physical characteristics that reflect their reliance on the
portion of the resource they use
– Ex: birds that eat larger seeds evolve larger bills
– Ex: birds that eat smaller seeds evolve smaller bills
Character displacement
The response of predator to prey and vice versa, over tens of
thousands of years, produces physical and behavioral changes, Coevolution is the interdependent evolution of two or more species.
Flowers have evolved colors and fragrances that attract bees, for example, while bees
have evolved vision that is most sensitive to the colors of the flowers they pollinate.
hosts and parasites become locked
in a duel of escalating adaptations
– Has been called an “evolutionary arms race”
– Each evolves new responses to the other
• It may not be beneficial to the parasite to kill its host
thousands of years, produces physical and behavioral changes, Coevolution is the interdependent evolution of two or more species.
Flowers have evolved colors and fragrances that attract bees, for example, while bees
have evolved vision that is most sensitive to the colors of the flowers they pollinate.
hosts and parasites become locked
in a duel of escalating adaptations
– Has been called an “evolutionary arms race”
– Each evolves new responses to the other
• It may not be beneficial to the parasite to kill its host
coevolution
evolution by one species to
resemble another species that is protected from
predators by a venomous stinger, bad taste, or
some other defensive adaptation.
• Harmless species evolve characteristics that mimic
unpalatable or poisonous species.
resemble another species that is protected from
predators by a venomous stinger, bad taste, or
some other defensive adaptation.
• Harmless species evolve characteristics that mimic
unpalatable or poisonous species.
Batesian Mimicry
Two unpalatable or dangerous
species evolve to look alike.
species evolve to look alike.
Mullerian Mimicry
a relationship in which one
organism (parasite) depends on another (host)
for nourishment or other benefit
organism (parasite) depends on another (host)
for nourishment or other benefit
Parasitism
Exploitation in
which animals feed on the
tissues of plants
– Widely seen in insects
– May not kill the plant, but affects
its growth and survival
• Defenses against herbivory
include:
– Chemicals: toxic or distasteful
parts
– Physical: thorns, spines, or
irritating hairs
– Other animals: protect the plant
which animals feed on the
tissues of plants
– Widely seen in insects
– May not kill the plant, but affects
its growth and survival
• Defenses against herbivory
include:
– Chemicals: toxic or distasteful
parts
– Physical: thorns, spines, or
irritating hairs
– Other animals: protect the plant
Herbivory
mutualism in which the organisms live in
close physical contact
– Each partner provides a service the other needs (food,
protection, housing, etc.)
• Microbes within digestive tracts
• Mycorrhizae: plant roots and fungi
• Coral and algae (zooxanthellae)
close physical contact
– Each partner provides a service the other needs (food,
protection, housing, etc.)
• Microbes within digestive tracts
• Mycorrhizae: plant roots and fungi
• Coral and algae (zooxanthellae)
Symbiosis
bees, bats, birds and others transfer pollen
from one flower to another, fertilizing its eggs
from one flower to another, fertilizing its eggs
Pollination
a relationship in
which one organism benefits, while the
other remains unaffected (neither
benefited nor harmed).
which one organism benefits, while the
other remains unaffected (neither
benefited nor harmed).
Commensalism
people interested in
how:
Species coexist and relate to one another
Communities change, and why patterns exist
how:
Species coexist and relate to one another
Communities change, and why patterns exist
Community ecologists
An organism’s feeding status in an ecosystem
trophic level
plants are these b/c they are converting solar energy into
chemical energy, producing food molecules.
chemical energy, producing food molecules.
producers
Other organisms in the ecosystem that use the chemical energy harnessed by the producers
consumers
use the geothermal energy
in hot springs or deep-sea vents to produce their
food
in hot springs or deep-sea vents to produce their
food
Chemosynthetic bacteria
second trophic level
– Organisms that consume producers
– Herbivores consume plants
• Deer, grasshoppers
– Organisms that consume producers
– Herbivores consume plants
• Deer, grasshoppers
Primary consumers
third trophic level
– Organisms that prey on primary consumers
– Carnivores consume meat
• Wolves, rodents
– Organisms that prey on primary consumers
– Carnivores consume meat
• Wolves, rodents
Secondary consumers
fourth trophic level
– Predators at the highest trophic level
– Consume secondary consumers
– Are also carnivores
– Hawks, owls
– Predators at the highest trophic level
– Consume secondary consumers
– Are also carnivores
– Hawks, owls
Tertiary Consumers
consumers that eat both plants and
animals
animals
Omnivores
scavenge waste products or dead
bodies
– Millipedes
bodies
– Millipedes
Detritivores
break down leaf litter and other non-living material
Decomposers
has a
strong or wide-reaching
impact far out of
proportion to its
abundance
strong or wide-reaching
impact far out of
proportion to its
abundance
Keystone Species
predators
at high trophic levels can
indirectly affect populations
of organisms at low trophic
levels by keeping species at
intermediate trophic levels in
check
at high trophic levels can
indirectly affect populations
of organisms at low trophic
levels by keeping species at
intermediate trophic levels in
check
Trophic Cascade
physically modify the
environment
environment
Ecosystem engineers
community of organisms resists change
and remains stable despite the disturbance
and remains stable despite the disturbance
Resistance
a community changes in response to a
disturbance, but later returns to its original state
disturbance, but later returns to its original state
Resilience
the predictable
series of changes in a
community following a
disturbance
series of changes in a
community following a
disturbance
Succession
disturbance eliminates all
vegetation and/or soil life
– Glaciers, drying lakes, volcanic
lava
vegetation and/or soil life
– Glaciers, drying lakes, volcanic
lava
Primary succession
the first
species to arrive in a primary
succession area (ex, lichens)
species to arrive in a primary
succession area (ex, lichens)
Pioneer species
a disturbance
dramatically alters, but does not destroy, all local
organisms
– The remaining organisms form “building blocks” for
the next population species
– Fires, hurricanes, farming, logging
dramatically alters, but does not destroy, all local
organisms
– The remaining organisms form “building blocks” for
the next population species
– Fires, hurricanes, farming, logging
Secondary succession
the community resulting from
successful succession
– Remains stable
until another
disturbance restarts
succession
successful succession
– Remains stable
until another
disturbance restarts
succession
Climax community
the overall character of the
community fundamentally changes
community fundamentally changes
Phase (regime) shift
viewed communities as
cohesive entities
– Its members remain associated over space and time
– The community shared similar limiting factors and
evolutionary histories
cohesive entities
– Its members remain associated over space and time
– The community shared similar limiting factors and
evolutionary histories
Frederick Clements
maintained that each species
responds independently to its own limiting factors
– Species can join or leave communities without greatly
altering the community’s composition
– The most widely accepted view of ecologists today
responds independently to its own limiting factors
– Species can join or leave communities without greatly
altering the community’s composition
– The most widely accepted view of ecologists today
Henry Gleason
non-native (exotic)
organisms that spread widely and become
dominant in a community
organisms that spread widely and become
dominant in a community
Invasive species
efforts to restore communities
• Restoration is informed by restoration ecology = the
science of restoring an area to an earlier condition
– To restore the system’s functionality (i.e. filtering of water by a
wetland)
– It is difficult, time-consuming, and expensive
• Restoration is informed by restoration ecology = the
science of restoring an area to an earlier condition
– To restore the system’s functionality (i.e. filtering of water by a
wetland)
– It is difficult, time-consuming, and expensive
Ecological restoration
major regional complex of similar
communities recognized by
communities recognized by
Biome
A climate diagram showing
an area’s mean monthly
temperature and
precipitation
– Similar biomes occupy
similar latitudes
an area’s mean monthly
temperature and
precipitation
– Similar biomes occupy
similar latitudes
Climatographs
lose their
leaves each fall and remain
dormant during winter
• Mid-latitude forests in
Europe, East China, Eastern
North America
• Fertile soils
• Forests = oak, beech, maple
leaves each fall and remain
dormant during winter
• Mid-latitude forests in
Europe, East China, Eastern
North America
• Fertile soils
• Forests = oak, beech, maple
Temperate deciduous forest
More extreme temperature
difference between winter and
summer
• Less precipitation
• Also called steppe or prairie
– Once widespread throughout
parts of North and South
America and much of central
Asia
– Much was converted for
agriculture
– Bison, prairie dogs, antelope,
and ground-nesting birds
difference between winter and
summer
• Less precipitation
• Also called steppe or prairie
– Once widespread throughout
parts of North and South
America and much of central
Asia
– Much was converted for
agriculture
– Bison, prairie dogs, antelope,
and ground-nesting birds
Temperate grasslands
Coastal Pacific Northwest
region
• Great deal of precipitation
• Coniferous trees: cedar,
spruce, hemlock, fir
• Moisture-loving animals
• Banana slug
• The fertile soil is susceptible
to erosion and landslides
• Provides lumber and paper
region
• Great deal of precipitation
• Coniferous trees: cedar,
spruce, hemlock, fir
• Moisture-loving animals
• Banana slug
• The fertile soil is susceptible
to erosion and landslides
• Provides lumber and paper
Temperate rainforest
Central America, South
America, southeast Asia, and
west Africa
• Year-round rain and warm
temperatures
• Dark and damp
• Lush vegetation
• Variety of animals and tree
species, but in low numbers
• Very poor, acidic soils
America, southeast Asia, and
west Africa
• Year-round rain and warm
temperatures
• Dark and damp
• Lush vegetation
• Variety of animals and tree
species, but in low numbers
• Very poor, acidic soils
Tropical rainforest
Tropical deciduous
forest
• India, Africa, South
America, northern
Australia
• Wet and dry seasons
• Warm, but less rainfall
• Converted to agriculture
• Erosion-prone soil
forest
• India, Africa, South
America, northern
Australia
• Wet and dry seasons
• Warm, but less rainfall
• Converted to agriculture
• Erosion-prone soil
Tropical dry forest
Grassland interspersed
with trees
• Africa, South America,
Australia, India
• Precipitation only during
rainy season
• Water holes
• Zebras, gazelles, giraffes,
lions, hyenas
with trees
• Africa, South America,
Australia, India
• Precipitation only during
rainy season
• Water holes
• Zebras, gazelles, giraffes,
lions, hyenas
Savanna
Minimal precipitation
• Some deserts are bare, with
sand dunes (Sahara)
• Some deserts are heavily
vegetated (Sonoran)
• They are not always hot
– Temperatures vary widely
• Saline soils
• Nocturnal or nomadic animals
• Plants have thick skins or
spines
• Some deserts are bare, with
sand dunes (Sahara)
• Some deserts are heavily
vegetated (Sonoran)
• They are not always hot
– Temperatures vary widely
• Saline soils
• Nocturnal or nomadic animals
• Plants have thick skins or
spines
Desert
Canada, Scandinavia,
Russia
• Minimal precipitation
– Nearly as dry as a desert
• Seasonal variation in
temperature
– Extremely cold winters
• Permafrost: permanently
frozen soil
• Few animals: polar bears,
musk oxen, caribou
• Lichens and low
vegetation with few trees
Russia
• Minimal precipitation
– Nearly as dry as a desert
• Seasonal variation in
temperature
– Extremely cold winters
• Permafrost: permanently
frozen soil
• Few animals: polar bears,
musk oxen, caribou
• Lichens and low
vegetation with few trees
Tundra
Canada, Alaska, Russia,
Scandinavia
• Variation in temperature
and precipitation
• Cool and dry climate
– Long, cold winters
– Short, cool summers
• Poor and acidic soil
• Few evergreen tree
species
• Moose, wolves, bears,
migratory birds
Scandinavia
• Variation in temperature
and precipitation
• Cool and dry climate
– Long, cold winters
– Short, cool summers
• Poor and acidic soil
• Few evergreen tree
species
• Moose, wolves, bears,
migratory birds
Boreal forest (taiga)
Mediterranean Sea,
California, Chile, and
southern Australia
• High seasonal
– Mild, wet winters
– Warm, dry summers
• Frequent fires
• Densely thicketed,
evergreen shrubs
California, Chile, and
southern Australia
• High seasonal
– Mild, wet winters
– Warm, dry summers
• Frequent fires
• Densely thicketed,
evergreen shrubs
Chaparral
Vegetative
communities change
along mountain slopes
– In the Andes, a
mountain climber
would begin in the
tropics and end up in a
glacier
Hiking up a mountain in the southwest U.S. is analogous to
walking from Mexico to Canada
communities change
along mountain slopes
– In the Andes, a
mountain climber
would begin in the
tropics and end up in a
glacier
Hiking up a mountain in the southwest U.S. is analogous to
walking from Mexico to Canada
Altitudes create patterns
low concentrations
of dissolved oxygen water
• Caused by fertilizer, runoff,
sewage
of dissolved oxygen water
• Caused by fertilizer, runoff,
sewage
Hypoxia
a network of relationships among
parts elements or components that interact
with and influence one another
– Exchange of energy, matter, or information
– Receives inputs of energy, matter, or
information; processes these inputs; and
produces outputs
• Systems often show behavior that is hard to
understand and predict
parts elements or components that interact
with and influence one another
– Exchange of energy, matter, or information
– Receives inputs of energy, matter, or
information; processes these inputs; and
produces outputs
• Systems often show behavior that is hard to
understand and predict
System
a system’s output serves as
input to that same system
– A circular process
input to that same system
– A circular process
Feedback loop
output that results from a system
moving in one direction acts as input that moves the system
in the other direction.
– Input and output essentially neutralize one another
– Stabilizes the system
– Example: body temperature
– Most systems in nature
moving in one direction acts as input that moves the system
in the other direction.
– Input and output essentially neutralize one another
– Stabilizes the system
– Example: body temperature
– Most systems in nature
Negative feedback loop
instead of stabilizing a system, it drives it
further toward one extreme or another
• Examples: exponential growth in human population, spread of
cancer, erosion
• Rare in nature
further toward one extreme or another
• Examples: exponential growth in human population, spread of
cancer, erosion
• Rare in nature
Positive feedback loop
system processes move in opposing
directions at equivalent rates,
balancing their effects
directions at equivalent rates,
balancing their effects
Dynamic equilibrium
a system
maintains constant or stable
internal conditions
maintains constant or stable
internal conditions
Homeostasis
system
characteristics not evident in the
components alone
– “The whole is more than the
sum of the parts”
characteristics not evident in the
components alone
– “The whole is more than the
sum of the parts”
Emergent properties
rock and sediment
Lithosphere
the air
Atmosphere
liquid, solid or vapor water
Hydrosphere
all the planet’s living organisms and
the abiotic portions of the environment
the abiotic portions of the environment
Biosphere
The process of nutrient overenrichment, blooms of
algae, increased production of organic matter, and
ecosystem degradation
algae, increased production of organic matter, and
ecosystem degradation
Eutrophication
conversion of solar energy to
chemical energy by autotrophs
chemical energy by autotrophs
Primary production
assimilation of
energy by autotrophs
energy by autotrophs
Gross primary production (GPP)
energy remaining
after respiration, and is used to generate biomass
– Available for heterotrophs
after respiration, and is used to generate biomass
– Available for heterotrophs
Net primary production (NPP)
biomass generated by
heterotrophs from consuming autotrophs
heterotrophs from consuming autotrophs
Secondary production
rate at which ecosystems generate
biomass
biomass
Productivity
ecosystems whose plants
rapidly convert solar energy to biomass
rapidly convert solar energy to biomass
High net primary productivity
elements and compounds required for survival that
are consume by organisms
are consume by organisms
Nutrients
nutrients required in relative large amounts
– Nitrogen, carbon, phosphorus
– Nitrogen, carbon, phosphorus
Macronutrients
nutrients needed in smaller amounts
– elements required either in small amounts by all life, or in moderate
amounts by some forms of life and not at all by others.
– elements required either in small amounts by all life, or in moderate
amounts by some forms of life and not at all by others.
Micronutrients
is the more important limiting factor for primary
productivity
In coastal ocean waters
Iron is an effective nutrient for open ocean waters
Satellite imagery gives scientists an improved view of productivity
at regional and global scales
productivity
In coastal ocean waters
Iron is an effective nutrient for open ocean waters
Satellite imagery gives scientists an improved view of productivity
at regional and global scales
Nitrogen
transitional zones between two
ecosystems in which elements of different
ecosystems mix
ecosystems in which elements of different
ecosystems mix
Ecotones
the study of landscape structure and how it
affects the abundance, distribution, and interaction of organisms
affects the abundance, distribution, and interaction of organisms
Landscape ecology
form the landscape, and are distributed spatially in
complex patterns (a mosaic)
I.e. forested patches within an agricultural landscape
complex patterns (a mosaic)
I.e. forested patches within an agricultural landscape
Patches
larger
than an ecosystem and
smaller than a biome
than an ecosystem and
smaller than a biome
Landscape
a network of subpopulations
– Most members stay within patches but may move
among patches or mate with those of other patches
– Individuals in small patches risk extinction
– Most members stay within patches but may move
among patches or mate with those of other patches
– Individuals in small patches risk extinction
Metapopulation
study the loss,
protection, and restoration of biodiversity
protection, and restoration of biodiversity
Conservation biologists
breaking habitat into
small, isolated patches due to human impact
small, isolated patches due to human impact
Habitat fragmentation
computer software used
in landscape ecology research
• Can analyze how elements within
the landscape are arranged to
help make planning and land-use
decisions
in landscape ecology research
• Can analyze how elements within
the landscape are arranged to
help make planning and land-use
decisions
Geographic information system
(GIS)
(GIS)
a simplified representation of a
complex natural process
complex natural process
model
constructs and tests
models
– To explain and predict how ecological systems work
• Researchers gather data and form a hypothesis
about relationships
– Models predict how the system will behave
models
– To explain and predict how ecological systems work
• Researchers gather data and form a hypothesis
about relationships
– Models predict how the system will behave
Ecological modeling
provided by the planet’s
systems
Soil formation, water and air purification, pollination
Breakdown of some pollutants and waste
Quality of life issues (inspiration, spiritual renewal)
Nutrient cycling
systems
Soil formation, water and air purification, pollination
Breakdown of some pollutants and waste
Quality of life issues (inspiration, spiritual renewal)
Nutrient cycling
Ecosystem services
the movement of nutrients
through ecosystems
– Atmosphere, hydrosphere, lithosphere, and biosphere
through ecosystems
– Atmosphere, hydrosphere, lithosphere, and biosphere
Nutrient (biogeochemical) cycle
where nutrients reside for varying
amounts of time
amounts of time
Pools (reservoirs)
movement of nutrients among pools, which change
over time and are influenced by human activities
over time and are influenced by human activities
Flux
pools that release more nutrients than they accept
Sources
accept more nutrients than they release
Sinks
summarizes how liquid, gaseous and solid water
flows through the environment
– Oceans are the main reservoir
– Less than 1% is available as fresh water
Evaporation = water moves from aquatic and land systems to air
(change from a liquid to a gas)
• Transpiration = release of water vapor by plants
• Precipitation = condensation of water vapor as rain or snow
Runoff : water that flows over the surface of the earth
• Infiltration: the movement of surface water into rock or soil
through cracks or pore spaces, where it becomes groundwater
flows through the environment
– Oceans are the main reservoir
– Less than 1% is available as fresh water
Evaporation = water moves from aquatic and land systems to air
(change from a liquid to a gas)
• Transpiration = release of water vapor by plants
• Precipitation = condensation of water vapor as rain or snow
Runoff : water that flows over the surface of the earth
• Infiltration: the movement of surface water into rock or soil
through cracks or pore spaces, where it becomes groundwater
Hydrologic cycle
release of water vapor by plants
Transpiration
condensation of water vapor as rain or snow
Precipitation
the movement of surface water into rock or soil
through cracks or pore spaces, where it becomes groundwater
through cracks or pore spaces, where it becomes groundwater
Infiltration
underground
reservoirs of “spongelike”
regions of rock and soil that
hold …
reservoirs of “spongelike”
regions of rock and soil that
hold …
Aquifers
water found
underground beneath layers
of soil
underground beneath layers
of soil
Groundwater
the upper limit
of groundwater held in an
aquifer
of groundwater held in an
aquifer
Water table
= describes the routes that carbon atoms take
through the environment
• Photosynthesis moves carbon from the air to organisms.
• Respiration returns carbon to the air and oceans.
• Decomposition returns carbon to the sediment (and rocks), the
largest reservoir of carbon.
– Ultimately, it may be converted into fossil fuels
• The world’s oceans are the second largest reservoir of carbon
through the environment
• Photosynthesis moves carbon from the air to organisms.
• Respiration returns carbon to the air and oceans.
• Decomposition returns carbon to the sediment (and rocks), the
largest reservoir of carbon.
– Ultimately, it may be converted into fossil fuels
• The world’s oceans are the second largest reservoir of carbon
Carbon cycle
describes the routes that nitrogen
atoms take through the environment
– Nitrogen gas is inert and cannot be used by organisms.
atoms take through the environment
– Nitrogen gas is inert and cannot be used by organisms.
Nitrogen cycle
Nitrogen gas is combined (fixed) with
hydrogen by nitrogen-fixing bacteria to become ammonium
– Which can be used
by plants
hydrogen by nitrogen-fixing bacteria to become ammonium
– Which can be used
by plants
Nitrogen fixation
bacteria that convert ammonium ions (NH4+) first into nitrite ions (NO2-) then into nitrate ions (NO3-)
Plants can take up these ions
Plants can take up these ions
Nitrification
convert nitrates in soil or water to
gaseous nitrogen, releasing it back into the atmosphere
gaseous nitrogen, releasing it back into the atmosphere
Denitrifying bacteria
synthetic production of fertilizers by
combining nitrogen and hydrogen to synthesize ammonia
– Dramatically changed the nitrogen cycle
– Humans are fixing as much nitrogen as nature does
combining nitrogen and hydrogen to synthesize ammonia
– Dramatically changed the nitrogen cycle
– Humans are fixing as much nitrogen as nature does
Haber-Bosch process
describes the routes that
phosphorus atoms take through the environment
– No significant atmospheric component
– Most phosphorus is within rocks and is released by weathering
– Weathering releases phosphate ions (PO4
3-
) into water.
– Some is taken up by plants, algae, & some bacteria.
– Phosphates dissolved in lakes /oceans, precipitate into solid form, settle to bottom
and reenter the lithosphere’s phosphorus reservoir in sediments.
• With naturally low environmental concentrations,
phosphorus is a limiting factor for plant growth
Phosphorus is a key component of cell
membranes, DNA, RNA, ATP and ADP
phosphorus atoms take through the environment
– No significant atmospheric component
– Most phosphorus is within rocks and is released by weathering
– Weathering releases phosphate ions (PO4
3-
) into water.
– Some is taken up by plants, algae, & some bacteria.
– Phosphates dissolved in lakes /oceans, precipitate into solid form, settle to bottom
and reenter the lithosphere’s phosphorus reservoir in sediments.
• With naturally low environmental concentrations,
phosphorus is a limiting factor for plant growth
Phosphorus is a key component of cell
membranes, DNA, RNA, ATP and ADP
Phosphorus cycle
called for an assessment of hypoxia in
the Gulf
the Gulf
Harmful Algal Bloom and Hypoxia Research and
Control Act (1998)
Control Act (1998)
competition
When multiple organisms seek the same limited resource, their relationship is said to be ___________.
Two species could divide a niche through “resource partitioning.”
Which of the following statements best describes competition for a niche?
intraspecific competition
If two members of the same bird species are competing for the same tree to build a nest in, this is considered_____.
− / −
Using “+” for those that benefit, “−” for those that are harmed, and “0” for no effect, which of the following expressions best represents competition between species?
The population of the predator increases.
When an increase in the population of prey occurs, which of the following usually occurs in the population of its predator?
0 / +
Using “+” for those who benefit, “−” for those who are harmed, and “0” for no effect, which of the following expressions for the host species and other species (respectively) represents commensalism?
exploitative
When a parasite lives inside the human gastrointestinal tract, absorbing some of the human’s nutrients at the human’s expense, it is considered a(n) _____ interaction.
herbivory
Many plants have developed complicated defenses to protect themselves against _____.
When a species is transported, it leaves behind its predators and the diseases that previously kept its population in check. Therefore the species is able to grow to large and damaging numbers.
When a species is moved from its native area to a new area, it can become an invasive species and damage its new ecosystem. What is one reason these species are able to do damage to an ecosystem?
mutualism and parasitism
Two relationships that can be a symbiosis are ___________.
omnivore
If a human consumes both plant and animal products then he or she is considered a(n) _____.
This statement is true because plants are able to convert sun energy into food energy and animals must get their energy from plants or other organisms that eat plants.
Pick the answer that best evaluates the following statement: “It has been said that land animals can’t exist without plants but that plants could exist without animals.”
a pyramid of energy
If you wanted to represent the relative importance of the trophic levels in a food chain, the most accurate way to do so would be a graph in the form of _____.
Carnivores
_____ are secondary consumers
5-10
Approximately _____% of the energy at one trophic level is passed on to the next highest trophic level.
10
10,000 kcal of producer could support approximately _____ kcal of tertiary consumer.
When organisms use cellular respiration to process energy only a small amount of energy is transferred to the next trophic level.
Which of the following statements is correct concerning organisms that use cellular respiration?
autotrophs
Which of the following would have the largest biomass in any given terrestrial ecosystem?
soil
Decomposers and detritivores are responsible for enhancing the _____ by recycling nutrients.
matter and energy
As organisms feed on one another, ______ and _____ move through the community from one trophic level to another.
producers
In an ecosystem, phytoplankton are _____.
detritivore
An earthworm that feeds on the remains of plants and animals is acting as a _____.
secondary consumer
When a human eats a steak, the human is acting as a _____.
primary consumer
A cow eating grass is an example of a _____.
A keystone species that is a predator controls the herbivore populations, which in turn maintains the plant populations and keeps balance.
Which statement is an accurate description of a keystone species?
a surface exposed by a retreating glacier
Which of these is a starting point for primary succession?
lichens and mosses
The first colonizing organisms during primary succession tend to be:
plants have wind-dispersed seeds
Which one of the following is a general characteristic of plants that are early colonizers during primary succession?
After a disturbance, the community goes through a somewhat predictable set of changes until reaching a final state.
Which statement is correct concerning the process of ecological succession?
temperature and rainfall
What are the two major factors determining the distribution of terrestrial biomes?
desert
Which of these biomes is characterized by little rainfall?
coniferous forest
Which of these is the largest terrestrial biome on Earth?
tropical rain forest
Which biome is characterized by an extensive canopy that allows little light to penetrate to the ground and by the presence of epiphytes?
tundra
Which biome is characterized by the presence of permafrost?
its annual rainfall and temperature
If you wanted to predict which biome you would find in an area, what two things would you would need to know about that area?
the tundra
Which of the following biomes has the least annual rainfall?
A temperate grassland biome has a hot, dry summer and fall, has few to no trees, and contains large grazing animals like bison.
Which biome is correctly matched with its description?
temperate grassland
The type of biome that has been converted most frequently by humans for agricultural use is the _____.
a temperature deciduous forest
While driving through an area in October you notice that most of the trees are full of beautiful autumn-colored leaves. When you return to the area again in December you notice that the trees have lost their leaves and are bare. Which of the following ecosystems might this be?
a climatograph
Which of the following types of graphs would a scientist reference when determining the biome of an area?
starting at the base of a mountain and climbing up to the top
When looking at the distribution of the world’s biomes, there is a predictable pattern that results when starting at the equator and moving north or south (a longitudinal change). Where else do we see the same sort of predictable pattern?
global recession
What do some believe could drive people back to the rain forests to farm?
negative
In a _____ feedback loop, output that results from a system acts as input that moves the system in the other direction.
are more common in natural systems altered by human actions,Human activities tend to create situations where positive feedback occurs. Deforestation can cause erosion, which can cause more loss of forest, which can lead to more erosion….
Positive feedback loops _______.
positive feedback loops, During positive feedback increased output in a system leads to increased input. This can be incredibly destabilizing for a system. Luckily this is found rarely in nature, but it is happening more and more often in systems that humans are affecting.
Which of the following would destabilize an ecosystem?
the characteristics that are not evident in the system’s individual components but are evident only by looking at the whole operating system
What does the term emergent properties describe?
its role as a habitat for other organisms in the ecosystem
Which of the following would be considered an emergent property of a tree?
the biosphere
The sum total of the planet’s living organisms and abiotic systems is ________.
lithosphere
The structural sphere of Earth that is best described as the rocks and sediment is the ______.
hydrosphere
The _____ encompasses all water in the biosphere.
fertilizer runoff from farms in the Mississippi River drainage
Which of the following best characterizes the factors that have contributed to the “dead zone” in the waters of the Gulf of Mexico for at least the last decade?
Dead zones are reversible if nutrient pollution input to a system is reduced.
Which of the following statements about dead zones is correct?
radiation from the sun, heat
Most energy in the majority of ecosystems arrives as ______ and exits in the form of _____.
energy flows through an ecosystem; nutrients cycle
Which best describes how energy and nutrients work in an ecosystem?
are said to have high primary productivity
Ecosystems that convert solar energy to biomass rapidly ________.
subtracting respiration from gross primary production
Net primary production in an ecosystem can be calculated by ______.
algal bed, desert
A(n) _____ is an example of an ecosystem with high primary productivity while a _____ is an example of an ecosystem with low primary productivity.
ecotone
The transitional zone between ecosystems is called a(n) _____.
ecological systems
A scientist can use ecological modeling to attempt to explain and predict how _______ function.
Water, water cycling
_____ is an example of a resource provided by our ecosystems, while _____ is(are) an example of a service provided by our ecosystems.
nitrogen gas (N2) is so stable that only a few organisms are capable of turning it into nitrogen that can be used for living things
Nitrogen availability is often a limiting factor in plant growth. Nitrogen tends to be scarce because ______.
ice sheets and glaciers.
The largest percentage of fresh water today is located in:
the bulk of all of the water found on Earth.
Earth’s oceans hold:
Most of the water that falls on the continents is derived from the oceans.
Which of the following is true of the hydrologic cycle?
through the process of transpiration
How do plants contribute to the water cycle?
aquifers
Some of the most ancient water on Earth can be found in ________.
warm temperatures and strong winds
Which two factors can speed up the process of evaporation?
decomposition
What name is given to the process by which detritivores return carbon to the atmosphere?
algae
Which of these removes carbon from the atmosphere?
dead organic matter and excreted wastes
Detritus is composed of _____.
the oceans
The largest reservoir of carbon in the carbon cycle is in sedimentary rock that may take hundreds of millions of years to return to the living portion of the cycle. What is the second largest reservoir of carbon?
photosynthesis
In the carbon cycle, carbon moves from the atmosphere into the living portion of the cycle through ______.
oxygen
Which of the following is an end product, or output, of photosynthesis?
ammonium … nitrites
Nitrifying bacteria convert _____ to _____.
Nitrogen fixation
_____ removes nitrogen from the atmosphere.
nitrates … nitrogen gas
Denitrifying bacteria convert _____ to _____.
NO2
Which one of these is a nitrite?
NO3
Which one of these is a nitrate?
Nitrogen fixation
_____ removes nitrogen from the atmosphere.
nitrogen fixation
The process that makes nitrogen available to plants by mutualistic and free-living bacteria is called _______.
the Haber-Bosch process
Which of the following processes was responsible for humans increasing nitrogen’s flux from the atmosphere to Earth’s surface?
rocks and soils
When considering the phosphorus cycle, plants obtain most of their phosphorus from _______.
