Transcript Ecology13

Ecology
The Biosphere
1
•Ecology is the scientific study of
interactions between organisms &
their environment, or
surroundings.
•An ecosystem is a collection of all
the organisms that live in a
particular place, together with
their nonliving, or physical,
environment.
2
•The biosphere contains all the
portions of the planet where all
life exists, including:
•Land, water, air or atmosphere
•The biosphere extends from about
8 kilometers above Earth's surface
to as far as 11 kilometers below
the surface of the ocean.
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Interactions & Interdependence
Biosphere
Biome
Ecosystem
Community
Population
Individual
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Interactions & Interdependence
•A species is a group of organisms
so genetically similar to one
another that they can breed and
produce fertile offspring.
•Populations are groups of
individuals that belong to the
same species and live in the
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same area.
Interactions & Interdependence
•Communities are groups of different
populations (species) that live
together in a defined area.
•Ecosystem is a community together with
its environment functioning as a unit.
•A biome is a group of ecosystems that
have the same climate and similar
dominant communities.
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Energy Flow
Where does the energy for life
processes come from?
•Without a constant input of
energy, living systems cannot
function.
Sunlight is the main energy
source for life on Earth.
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•Autotrophs use energy from sunlight
to turn simple inorganic compounds
into complex organic molecules.
Only plants, some algae
(cyanobacteria), and certain bacteria
can capture energy from sunlight and
use that energy to produce food.
Because they make their own food,
autotrophs are called producers.
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•Most autotrophs use sunlight in a
process known as photosynthesis.
oDuring photosynthesis, these
autotrophs use light energy to convert
carbon dioxide and water into oxygen
and energy-rich carbohydrates.
oPhotosynthesis is responsible for
adding oxygen to— and removing CO2
from—Earth's atmosphere.
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Energy Flow
10
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• Many organisms cannot harness
energy directly from the physical
environment.
• Organisms that rely on other
organisms for their energy and
food supply are called
heterotrophs.
oHeterotrophs are also called
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consumers.
•There are different heterotrophs.
Herbivores eat plants.
Carnivores eat animals.
Omnivores eat plants and animals.
Detrivores (scavengers) feed on plant
and animal remains and dead matter.
Decomposers, like bacteria and
fungi, break down organic matter.
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Feeding Relationships
• The relationships between producers
and consumers connect organisms
into feeding networks based on who
eats whom.
• Energy flows through an ecosystem in
one direction, from the sun or
inorganic compounds to autotrophs
(producers) and then to various
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heterotrophs (consumers).
Feeding Relationships
•Food Chains
•A food chain is a series of steps in
which organisms transfer energy by
eating and then being eaten.
Small Fish
Zooplankton
Squid
Algae
Shark
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• Food Webs
Feeding Relationships
–Ecologists describe a
feeding relationship in
an ecosystem that forms
a network of complex
interactions as a food
web.
–A food web links all the
food chains in an
ecosystem together.
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•Each step in a food chain or food
web is called a trophic level.
•Producers always make up the
first trophic level.
•Consumers make up the second,
third, or higher trophic levels.
•Each consumer depends on the
trophic level below it for energy.
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•An ecological pyramid is a diagram
that shows the relative amounts of
energy or matter contained within
each trophic level in a food chain or
food web.
•There are three kinds:
Energy pyramids
Biomass pyramids
Pyramids of numbers
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•Energy Pyramid: The 10% Rule
•Only part of the energy that is
stored in one trophic level is passed
on to the next level.
•About 10% of the energy is passed
on to the next (higher)
trophic
level
0.1% Third-level
consumers
1% Second-level
consumers
10% First-level
consumers
100%
Producers
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• Biomass Pyramid
• The total weight of
living tissue within a
given trophic level is
called biomass.
• A biomass pyramid
represents the mass
amount of potential
food available for
each trophic level in
an ecosystem.
Feeding Relationships
50 grams of
human tissue
500 grams of
chicken
5000 grams
of grass
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•Pyramid of
Feeding Relationships
Numbers
1
•A pyramid of
10
numbers shows
100
the relative count
of individual
organisms at each 1000
trophic level.
*10% Rule is NOT exact.
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The Living and the Non living:
Biotic & Abiotic Factors
• The biological influences on
organisms within an ecosystem
are called biotic factors.
• Biotic factors include all the living
things with which an organism
might interact.
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• Physical, or nonliving, factors that
shape ecosystems are called abiotic
factors. These may include:
– temperature
– precipitation
– humidity
– wind
– nutrient availability
– soil type
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– sunlight
Biotic & Abiotic Factors
• The area where an organism lives is
called its habitat. A habitat includes
both biotic and abiotic factors.
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• A niche is the full range of physical and
biological conditions in which an organism
lives and the way in which the organism
uses those conditions.
–EX: The range of temperatures needed
and the place in the food web of a
specific snake
–The total combination of biotic and
abiotic factors in an ecosystem often
determines the number of different
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niches in that ecosystem.
Community Interactions
• Competition occurs
• When organisms of the same or
different species try to use the same
ecological resource (any necessity of
life, such as water, nutrients, space),
at the same place/time.
• The competitive exclusion principle
states that two species
• cannot occupy the same niche or
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habitat at the same time.
Community Interactions
• These warblers avoid direct
competition, because each species
feeds in a different part of the tree.
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Community Interactions
•An interaction in which one organism
captures and feeds on another
organism is called predation.
•The organism that does the killing and
eating is called the predator.
•The food organism, often running and
screaming is the prey.
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Community Interactions
•Any relationship in which two
different species live very closely
together is called symbiosis.
•Symbiotic relationships include:
–mutualism
–commensalism
–parasitism
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Community Interactions
•Mutualism: both species benefit from
the relationship.
–Nitrogen fixing bacteria: lives on
roots of legumes. The bacteria
make nitrogen compounds to be
used by the plants. The plants give
the bacteria moisture and
Bees and Flowering Plants exhibit mutualism
nutrients.
Humans and E. coli
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Community Interactions
•Commensalism: one member of the
association benefits and the other is
neither helped nor harmed.
–Sharks: the remora attaches to
the shark and gets uneaten bits of
food. The shark gets nothing but is
unharmed.**
Nurse
shark
Shark
Remora
andReef
Sea Turtle
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Community Interactions
•Parasitism: one organism lives on or
inside another organism and harms it.
–Athlete’s foot: the parasites feed
on the host.
–Schistosoma Worms
–Mosquitoes are parasites!
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Community Interactions
Symbiosis Organism Organism
1
2
Mutualism
+ gains
Commensalism
+ gains
Parasitism
+ gains
+ : gain - : loss
0 : no effect
+ gains
0 no effect
- loses
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Succession
• Sometimes,
–
Ecosystems change;
an ecosystem
older
inhabitants
changes
in response
graduallyto
dieanout
abrupt
and
new organisms
disturbance.
(asteroid
move in,impact!)
this
in the community.
– causes
At otherchanges
times, change
occurs as a
• more
Thesegradual
series ofresponse
changes to
in natural
a
community over
fluctuations
in thetime
environment.
is called
ecological
(Earth’s
rotation/length
succession. of day)
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• On land, succession that occurs on
surfaces where no soil exists is called
primary succession. For example,
primary succession occurs on rock
surfaces formed after volcanoes
erupt.
• The first species to populate the area
are called pioneer species.
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Primary Succession Stages
1.A volcano destroys the land leaving only rock
2.Lichens appear.
3.Mosses and grasses appear.
4.Tree seedlings and shrubs move in.
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• The ecosystem can be changed by
natural events, such as fires.
• After the disturbance, community
interactions can restore the
ecosystem to its original condition
through secondary succession.
• Healthy ecosystems usually recover
o Once
the populations
arebut
fairly
from
natural
disturbances,
may
forfrom
a long
timehuman
we call it
notstable
recover
larger
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a climax community
Biomes
• A biome is a complex of terrestrial
communities that covers a large area
• Characterized by certain soil and
climate conditions and specific plants
and animals.
–Variations in plants and animals
help different species survive under
different conditions in different
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biomes.
Biomes
–Plants and animals exhibit
variations in tolerance, or
the ability to survive and
reproduce under conditions
that differ from their optimal
conditions.
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Biomes and Climate
•The climate of a region is an important
factor in determining which organisms
can survive there.
•Within a biome, temperature and
precipitation can vary over small
distances. eg a valley on a mountain.
•The climate in a small area that differs
from the climate around it is called a
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microclimate.
Average Precipitation (mm)
Biomes
Average Temperature (°C)
• Two
components
of climate,
temperature
and
precipitation,
can be
summarized in
a graph called
a climate
diagram.
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• The world's major biomes include:
– tropical rain forest
– tropical dry forest
– tropical savanna
– desert
– temperate grassland
– temperate woodland and shrubland
– temperate forest
– northwestern coniferous forest
– boreal forest
– tundra
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60°N
30°N
0° Equator
30°S
60°S
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Ten Major Biomes
Biome
Tropical Rain
Forest
Tropical Dry
Forest
Tropical
Savanna
Desert
Temperate
Grassland
Temperate
woodland and
Shrubland
Temperate
Forest
Northwestern
Coniferous
Forest
Boreal Forest
Tundra
Precipitation Temperature
high
hot
Soil
poor
Diversity
high
Trees
dense
Grasses
sparse
variable
rich
moderate
medium
medium
mild
Which one is ours? Circle it!
variable
mild
clay
moderate
sparse
dense
low
moderate
variable
summer hot
poor
rich
moderate
moderate
sparse
absent
sparse
dense
summer low, summer hot
winter
moderate
moderate
summer
moderate,
winter cold
high
summer mild,
winter cold
poor
low
medium
medium
rich
high
dense
sparse
rocky,
acidic
low
dense
sparse
moderate
poor, acidic moderate
dense
sparse
poor
absent
medium
low
summer mild,
winter cool
summer mild,
winter cold
low
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Biomes
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Biomes
Tropical Rain Forests
• Tropical rain forests are home to
more species than all other biomes
combined.
• Abiotic factors: hot and wet yearround; thin, nutrient-poor soils
• Plants: broad-leaved evergreen
trees; ferns; large woody vines and
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climbing plants.
Tropical Rain Forest
• Wildlife: sloths, capybaras, jaguars,
anteaters, monkeys, toucans,
parrots, butterflies, beetles,
piranhas, caymans, boa
constrictors, and anacondas.
• Location: parts of South and
Central America, Southeast Asia,
parts of Africa, southern India, and
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Tropical Dry Forest
• During the dry season, most trees
drop their leaves to conserve water.
• Abiotic factors: generally warm
year-round; alternating wet and dry
seasons; rich soils subject to erosion
• Plants: tall, deciduous trees;
drought-tolerant plants; aloes and
other succulents
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Tropical Dry Forest
• Wildlife: tigers, monkeys, elephants,
Indian rhinoceroses, hog deer, great
pied hornbills, pied harriers, spotbilled pelicans, termites, snakes and
monitor lizards
• Location: parts of Africa, South and
Central America, Mexico, India,
Australia, and tropical islands
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Tropical Savanna
• Compact soils, frequent fires, and the
action of large animals prevent them
from becoming dry forest.
• Abiotic factors: warm temps; seasonal
rains; compact soil; frequent fires set
by lightning
• Plants: tall, perennial grasses; droughttolerant/fire-resistant trees or shrubs50
Tropical Savanna
• Wildlife: lions, leopards, cheetahs,
hyenas, jackals, aardvarks, elephants,
giraffes, antelopes, zebras, baboons,
eagles, ostriches, weaver birds, and
storks
• Location: large parts of eastern
Africa, southern Brazil, and northern
Australia.
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Desert
• All deserts are dry, defined as having
annual precipitation of less than 25
centimeters.
• Abiotic factors: low precipitation;
variable temperatures; soils rich in
minerals but poor in organic material
• Plants: cacti and other succulents;
plants with short growth cycles
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Desert
Wildlife: mountain lions, gray foxes,
bobcats, mule deer, pronghorn
antelopes, desert bighorn sheep,
kangaroo rats, bats, owls, hawks,
roadrunners, ants, beetles, butterflies,
flies, wasps, tortoises, rattlesnakes, and
lizards
Location: Africa, Asia, the Middle East,
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U.S., Mexico, S. America, and Australia
Temperate Grassland
Periodic fires and heavy grazing by
large herbivores maintain the unique
plant community.
Abiotic factors: warm-hot summers;
cold winters; moderate, seasonal
precip.; fertile soils; occasional fires
Plants: lush, perennial grasses and
herbs; most are resistant to drought,
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fire, and cold
Temperate Grassland
Wildlife: coyotes, badgers, pronghorn
antelopes, rabbits, prairie dogs,
introduced cattle, hawks, owls,
bobwhites, prairie chickens, mountain
plovers, snakes, ants and grasshoppers
Location: central Asia, North America,
Australia, central Europe, and upland
plateaus of South America
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Temperate Woodland and Shrubland
• This biome is characterized by a
semiarid climate and mix of shrub
communities and open woodlands.
• Abiotic factors: hot, dry summers;
cool, moist winters; thin, nutrientpoor soils; periodic fires
• Plants: woody evergreen shrubs;
herbs that grow during winter and
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die in summer
Temperate Woodland and Shrubland
• Wildlife: coyotes, foxes, bobcats,
mountain lions, black-tailed deer,
rabbits, squirrels, hawks, California
quails, warblers, lizards, snakes, and
butterflies
• Location: western coasts of North and
South America, areas around the
Mediterranean Sea, South Africa, and
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Australia
Temperate Forest
These forests have cold winters that
halt plant growth for several months.
Abiotic factors: cold to moderate
winters; warm summers; year-round
precipitation; fertile soils
Plants: broadleaf deciduous trees;
some conifers; flowering shrubs;
herbs; a ground layer of moss & ferns58
Temperate Forest
• Wildlife: deer, black bears,
bobcats, squirrels, raccoons,
skunks, songbirds, turkeys.
• Location: eastern United States,
southeastern Canada, most of
Europe, parts of Japan, China,
and Australia. This is your biome!
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Northwestern Coniferous Forest
• Moist air from the Pacific Ocean
provides abundant rainfall
• Abiotic factors: mild temperatures;
abundant precipitation during fall,
winter and spring; cool dry summer;
rocky, acidic soil.
• Plants: Douglas fir, Sitka spruce,
western hemlock, redwood.
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Northwestern Coniferous Forest
• Wildlife: bears, elk, deer, beavers,
owls, bobcats, and members of
the weasel family
• Location: Pacific coast of
northwestern United States and
Canada, from northern California
to Alaska.
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Boreal Forest (Taiga)
These forests are called boreal forests,
or taiga. Winters are bitterly cold.
Abiotic factors: long, cold winters;
short, mild summers; moderate
precipitation; high humidity; acidic,
nutrient-poor soils
Plants: needleleaf conifers & broadleaf
deciduous trees; small, berry shrubs 62
Boreal Forest (Taiga)
• Wildlife: lynxes, timber wolves,
members of the weasel family,
small herbivorous mammals,
moose, beavers, songbirds, and
migratory birds
• Location: North America, Asia,
and northern Europe
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Tundra
• Characterized by permafrost, a layer
of permanently frozen subsoil.
• Abiotic factors: strong winds; low
precip.; short, soggy summers; long,
cold, dark winters; poorly developed
soils; permafrost
• Plants: ground plants such as mosses,
lichens, sedges, & short grasses
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Tundra
• Wildlife: birds, mammals that can
withstand the harsh conditions,
migratory waterfowl, shore birds,
musk ox, Arctic foxes, caribou,
lemmings and other small rodents
• Location: northern North
America, Asia, and Europe
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Other Areas
• Mountain ranges and polar icecaps
do not fit into any major biomes.
• Nearly 75% of the Earth’s surface is
covered with water.
• Aquatic ecosystems are determined
primarily by depth, flow,
temperature, and chemistry of the
overlying water. NOT ANIMALS
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Freshwater
• Flowing-water ecosystems
• Rivers, streams, and brooks are
freshwater that flows over land.
• Downstream, water may meander
slowly, turtles, beavers & otters live.
• Standing-water ecosystems
• Lakes and ponds are standing-water
ecosystems.
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A Wetland is an ecosystem in which
water covers the soil or is present at
or near the surface of the soil at least
part time.
• The water in wetlands may flow or be
standing; fresh, salty, or brackish.
• The three main types of freshwater
wetlands are bogs, marshes, and
swamps.
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Marine Ecosystems
•The well-lit upper layer of the ocean is
known as the photic zone. (for light)
•Algae and other producers can grow
only in this thin surface layer.
•Below the photic zone is the aphotic
zone, which is permanently dark.
•Chemosynthetic autotrophs are the
only producers that can survive here69
Marine Ecosystems
• In addition to the division between
photic and aphotic zones, marine
biologists divide the ocean into
zones based on the depth and
distance from shore:
– the intertidal zone
– the coastal ocean
– the open ocean
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Land
200 m
1,000 m
Coastal
ocean
Open
ocean
4,000 m
6,000 m
Continental
shelf
Continental
slope
and continental
rise
Ocean
trench
Abyssal
plain
Photic
zone
Apho
tic
zone
10,000 m
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Intertidal Zone
• Organisms that live in the intertidal
zone are exposed to regular and
extreme changes in surroundings.
• Competition among organisms in the
rocky intertidal zone often leads to
zonation: an arrangement of
organisms in a particular habitat in
horizontal bands.
72
Coastal Ocean
• The coastal ocean extends from the
low-tide mark to the outer edge of
the continental shelf.
• It falls within the photic zone, and
photosynthesis occurs throughout its
depth.
• The coastal ocean is often rich in
plankton and many other organisms.
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Coral Reefs
• Coral reefs, found in tropical coastal
waters, are named for the coral
animals whose skeletons of calcium
carbonate A.K.A.
• limestone make up their primary
structure.
• An extraordinary biodiversity of
organisms exists among coral reefs. 74
Open Ocean
• The
open
ocean,
the
oceanic
zone,
Who are
ARGUABLY
THE
most
important
organism on Earth since they produce most of
extends
from
the
edge
of
the
Earth’s oxygen!!
continental shelf outward.
• It is the largest marine zone.
• Most of the photosynthetic activity
on Earth occurs in the photic zone
of the open ocean by the smallest
producers, mainly algae
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Benthic Zone
• The ocean floor contains organisms
that live attached to or near the
bottom.
• These organisms are called benthos.
The ocean floor is called the benthic
zone.
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Benthic Zone
• Benthic ecosystems often depend on
food from organisms that grow in the
photic zone.
• Chemosynthetic primary producers
support life without light near deepsea vents using chemicals to create
energy not sunlight!
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Video
Review
Biomes
78
Ecology
Populations
79
Populations
• 3 important characteristics of a
population are its:
–geographic distribution: or
where
–Population density or How many
–growth rate: how fast it increases
or decreases.
80
• 3 factors can affect population size:
–the number of births
–the number of deaths
–the #of individuals that enter
(immigrate)
–or leave (emigrate) the population
• A population grows when:
• birthrate is greater than death rate.
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• Under ideal conditions with
unlimited resources, a population
will grow exponentially.
• Exponential growth occurs when
the individuals in a population
reproduce at a constant rate.
• The population becomes larger and
larger until it approaches an
infinitely large size.
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Populations
Exponential Growth
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Logistic Growth
• In nature, exponential growth can not
continue in a population for very long.
• As resources run out, the growth
slows or stops.
• Logistic growth occurs when a
population's growth slows or stops
following a period of exponential
growth.
84
• Called an S curve
Populations
85
Carrying Capacity
• The largest number of individuals of a
population that a given environment
can support is called its carrying
capacity.
• When a population reaches the
carrying capacity of its environment,
its growth levels off. The average
growth rate is zero.
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Limiting Factors
• A limiting factor is one that when it is
reduced it results in end of most
growth in the ecosystem.
• EX A limiting nutrient/food
• In the context of populations, a
limiting factor is a factor that causes
population growth to decrease and
stop
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• A limiting factor that depends on population
size is called a density-dependent limiting
factor.
• Density-dependent limiting factors include:
Competition (for food, space, mates…)
 Predation
Parasitism
Disease
• These factors occur more when a population
is large and dense.
•Small, scattered populations are not
affected as much.
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Populations
Population
Growth
can be
Logistic
Exponential
growth
characterized by
No limits on
growth
Unlimited
resources
growth
represented by
Constant
growth rate
characterized by
Limits on
growth
J-shaped
curve
represented by
S-shaped
curve
which cause a
Falling
growth rate
Fill in the Missing Circles!
89
Competition
•• Competition
will
also
occur
between
When populations become
members
of
different
species.
crowded, organisms compete for
o This
lead toand
food,competition
water space,can
sunlight
evolutionary
change.
other essentials.
o
time, theamong
species
may evolve
• Over
Competition
members
of the
to
occupy
different
niches. (see
same
species
is a densitywarblers,
finches,
etc.)
dependent
limitingmammals,
factor (depends
on population
density) are stable
o But
once the populations
it’s reached its climax community
90
Populations
Predation
• Populations in nature are often
controlled by predation.
• The regulation of a population by
predation takes place within a
predator-prey relationship, one
of the best-known mechanisms
of population control.
91
Populations
Wolf and Moose Populations on Isle Royale
Moose
Wolves
92
Populations
Parasitism and Disease
• Parasites can limit the growth of
a population.
• A parasite lives in or on another
organism (the host) and
consequently harms it.
Eyelash mite aka Demodex folliculorum *generally
commensal and NOT a true parasite, but scary to think about!
93
• Density-independent limiting factors
affect all populations in similar ways,
regardless of the population size.
• Examples of density-independent limiting
factors include:
unusual weather
natural disasters
seasonal cycles
human activities—such as damming
rivers and clear-cutting forests
Kaibab Deer
94
Human Population
DO NOW:
• If the human population continues
to grow at a rate of 1.4 percent per
year, the population would double
in size (to 12 billion people) in only
51 years! What effect might this
increase in population have on the
environment and on other people?
95
The size of the human population tends to
increase with time.
For most of human existence, the population
grew slowly.
Limiting factors kept population sizes low.
(disease, scarce food sources)
About 500 years ago, the human population
began growing rapidly.
Life was made easier and safer by advances
in agriculture and industry.
Death rates were reduced due to improved
sanitation, medicine, and healthcare, while
birthrates increased.
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Human Population
Our advances allowed for exponential
Human Population Growth
growth.
97
Human Population
• Yet, over the past century,
population growth in the USA,
Japan, and much of Europe
has slowed dramatically.
• This dramatic change in birth
and death rates is called a
demographic transition.
98
The demographic transition has 4 main stages
– In stage 1, there are high death rates and high
birthrates called Pre-industrial
– In stage 2, the death rate drops, while the
birthrate remains high. The population increases
rapidly. Called Developing or Urbanizing
– In stage 3, the birthrate begins to decrease,
causing population growth to slow but still
above the death rate. Called Mature Industrial
– In stage 4 birthrate drops drastically and
*matches the now stable low death rate. Called
Post Industrial.
99
The
demographic
transition is
complete
when the
birthrate falls
to meet the
death rate,
and
population
growth stops.
Human Population
100
• Population growth depends, in part,
on how many people of different
ages make up a given population.
• Demographers can predict future
growth using models called agestructure diagrams.
• Age-structure diagrams show the
population of a country broken down
by gender and age group.
101
Human Population
U.S. Population
In the USA, there are
80+
almost equal
numbers of people
60–64
Population predictors assume that those
in each age
who group.
reach child bearing age will have
children. While on average
40–44 this is
This age structure
generally true, it is NOT always true.
diagram predicts a
20–24
slow but steady
growth rate for the
0–4
8 6 4 2 0 2
near future.
Females
Age (years)
Males
4
6 8
102
Percentage of Population
In Rwanda, there are
many more young
Rwandan Population
children than
80+
teenagers, and
60–64
many more
teenagers than
adults.
40–44
This age structure
diagram predicts a 20–24
population that will
double in about 30 0–4
Percentage of Population
103
years.
Age (years)
Males
Females
104
Human Population
• Ecologists suggest that if growth
does not slow down, there could
be serious damage to the
environment and global economy.
• Economists assert that science,
technology, and changes in society
may control the negative impact of
population growth.
Human Population Graph
105
Human Impact & Sustainability
DO NOW:
• What positive effect have
humans had on their
environment?
• What negative effect have
humans had on their
environment?
106
Ecologists refer to necessities that humans
get from the ecosystem as “ecosystem
goods and services” because they are
needed have value to individuals and
societies.
To obtain these resources human activities
have drastically affected the biosphere:
Hunting & gathering resources
Agriculture & industry
Urban development
107
Human Impact
Challenges for the Future
• While increasing world food supplies,
modern agriculture has created
ecological problems. For example:
–Monoculture or one crop use (corn)
leads to problems with insect pests and
diseases only curable by chemicals
–water for irrigation is becoming more
scarce.
108
Industrial Growth and Urban Impact
• The Industrial Revolution added
machines and factories.
• The energy comes mostly from fossil
fuels: coal, oil, and natural gas.
• Industrial waste pollutes air, water, and
soil.
• Dense human communities also produce
waste.
• Suburban growth consumes farmland
and kills native plants and animals.
109
Fill in the blanks!
Human
Activities
that have changed the biosphere include
Hunting and
gathering
may have once caused
Industrial
growth
Agriculture
Urban
development
often relies on the methods of the
have resulted in
Modern
agriculture
Extinctions of
large animals
High standard
of living
Increased
pollution
which increased
Food supply
Pesticide use
Monocultured
crop
use
110
• Human Impact on resources: 2 categories
• Renewable resources can regenerate, or
can be replenished by biogeochemical
cycles in a reasonable amount of time
• Examples: wood, carbon, nitrogen.
• A nonrenewable resource is one that
cannot be replenished by natural
processes in a reasonable time.
• Examples: coal, oil, gold, iron
111
Human Impact on Resources:
Sustainable development is a way of
using natural resources without
depleting them, and without causing
long-term environmental harm.
Land provides space for human
communities and raw materials for
industry. Land also includes the soils in
which crops are grown.
If managed soil’s a renewable resource
112
Soil erosion is the wearing away of
surface soil by water and wind.
–Plowing the land removes the roots
that hold the soil in place, which
increases the rate of soil erosion.
• Desertification is the process by which
productive areas are turned into
deserts. Desertification is caused by a
combination of farming, overgrazing,
and drought.
113
• A variety of sustainable-development
practices can prevent problems such
as soil erosion and desertification.
• contour plowing: fields are plowed
across the slope of the land to reduce
erosion
• leaving stems and roots after harvest
in place to help hold the soil
• planting a field with rye rather than
leaving it unprotected from erosion114
Earth’s forests are an important
resource because they provide wood
for products and fuel:
remove carbon dioxide and produce
oxygen. Forests store nutrients.
provide habitats and food for
organisms.
moderate climate, limit soil erosion.
protect water from pollution.
115
Deforestation
• Loss of forests, or deforestation,
has several effects:
–Erosion can wash away
nutrients in the topsoil.
–Grazing or plowing can
permanently destroy soils and
microclimates, which kills more
vegetation.
116
Sustainable Forest Management
• Mature trees can be harvested
selectively to promote the growth of
younger trees and preserve the
forest ecosystem.
• replanting
• Tree geneticists are breeding new,
faster-growing trees that produce
high-quality wood.
117
Fish as Resources
• Overfishing, or harvesting fish faster
than they can be replaced by
reproduction, has greatly reduced the
amount of fish in parts of the world’s
oceans.
• Until recently, fisheries seemed to be a
renewable resource, but overfishing has
changed all that!! Without change by
2048 most oceans are predicted to be
unfishable
118
Sustainable Development
• The U.S. National Marine Fisheries Service
has issued guidelines that specify how
many fish, and of what size, can be caught
in various parts of the oceans.
• They have helped some fish populations
recover.
• Aquaculture or fish farming: The raising of
aquatic animals for human consumption,
which is called aquaculture, is also helping
to sustain fish resources.
119
Protected Fish Stock
120
Biodiversity
Watch the video. Why are other organisms
important?
121
Biodiversity
Insects
54.4%
Protists
4.2%
Other Animals
19.7%
Plants
18%
Fungi Bacteria
0.3%
3.4%
Species Biodiversity
122
• Biodiversity, is all of the variety, of all
organisms in the biosphere.
• Ecosystem diversity includes the
variety of habitats, communities, and
ecological processes on Earth
• Species diversity is the number of
different species in the biosphere.
• Genetic diversity is the total of all the
different forms of genetic information
carried by all organisms on Earth. 123
Biodiversity
• Biodiversity is one of Earth's
greatest natural resources.
• Species of many kinds have
provided us with foods, industrial
products, and medicines—
including painkillers, antibiotics,
heart drugs, antidepressants, and
anticancer drugs.
124
Threats to Biodiversity
• Human activity can reduce
biodiversity by:
–altering habitats
–hunting species to extinction
–introducing toxic compounds into
food webs
–introducing invasive species to
new environments
125
Biodiversity
• Extinction occurs when a species
disappears from all or part of its range.
• A species whose population size is
declining in a way that places it in
danger of extinction is called an
endangered species.
• As the population of an endangered
species declines, the species loses
genetic diversity.
126
Habitat Alteration
• When land is developed, natural
habitats may be destroyed.
• Development often splits ecosystems
into pieces, a process called habitat
fragmentation.
• The smaller a species’ habitat is, the
more vulnerable the species is to
further disturbance.
127
Demand for Wildlife Products
• Throughout history, humans have
pushed animal species to extinction by
hunting them for food or products.
• Today, in the U.S., endangered species
are protected from hunting.
• The Convention on International Trade
in Endangered Species,bans
international trade in products derived
from endangered species.
128
Pollution
• Many forms of pollution threaten
biodiversity.
• One of the most serious problems
occurs when toxic compounds
accumulate in the tissues of
organisms.
• DDT, one of the first pesticides, is a
good example of this.
129
For a long time DDT was considered
harmless, and it drained into rivers and
streams in low concentrations.
DDT has two hazardous properties:
–It is nonbiodegradable, which means that
it cannot be broken down by organisms.
–Once DDT is picked up by organisms, it
cannot be eliminated from their bodies.
130
• When DDT enters food webs, it
undergoes biological magnification.
• In biological magnification,
concentrations of a harmful
substance increase in organisms at
higher trophic levels in a food chain
or food web.
• In 1962, biologist Rachel Carson
wrote Silent Spring, which alerted
people to the dangers of biological
131
magnification.
Fish-Eating Birds
Magnification of
DDT Concentration
10,000,000
Large
Fish
Small Fish
1,000,000
100,000
Biomagnification
Zooplankton 10,000
Producers
Water
1000
1
132
• The widespread use of DDT
threatened populations of many
animals—especially fish-eating
birds like the bald eagle—with
extinction.
• By the early 1970s, DDT was
banned in the U.S. and in most
other industrialized countries; as
a result, affected bird populations
have recovered.
133
Another threat to biodiversity comes from
plants and animals that humans transport
around the world (on purpose or not).
Invasive species are introduced species
that reproduce rapidly because their new
habitat has no predators to control their
population. Ex. zebra mussels in the Great
Lakes
Hundreds of invasive species are causing
ecological problems in the United States.
134
Biodiversity
Conserving Biodiversity
• Conservation is the wise
management of natural
resources, including the
preservation of habitats and
wildlife.
135
Strategies for Conservation
• Many conservation efforts are aimed
at managing individual species to
keep them from becoming extinct.
• Conservation efforts focus on
protecting entire ecosystems as well
as single species.
• Protecting an ecosystem ensures that
the natural habitats of many different
species are preserved.
136
Conservation Challenges
• Protecting resources for the
future can require people to
change the way they live and earn
their living today.
• Conservation regulations must be
informed by solid research and
must try to maximize benefits
while minimizing economic costs.
137
Our Future
• Human alteration of the
atmosphere & Earth means
Invasive Species may be able to
live in places where they once
could not.
• Other organisms may become
threatened or extinct in areas
where they once thrived.
138
Our Future
• DO NOW: Write down how
much you would be willing
to pay for:
1. Fresh, clean drinking water
2. Clean air to breathe
3. An endangered plant containing
a substance that can cure cancer
4. Gas for your family car
139
Our Possible Future
140
Our Future
141
Our Future
• One sign
of global
warming
is melting
polar ice.
142