Transcript Notes Ecology BIO.B.4

ECOLOGY
BIO.B.4
Ecology
• Ecology – the study of interactions
among and between organisms and their
environment
Organizational Groups
• Levels of Organization (small to large)
– Species – group of organisms that can
breed and produce fertile offspring
– Populations – groups of the same
species that live in the same area
– Communities – groups of different
populations (therefore different species)
that live in the same area
– Ecosystem – all of the organisms
that live in a particular place,
together with their nonliving
environment
– Biome – a group of ecosystems that
have the same climate and similar
dominant communities
• Examples:
– Biosphere – part of Earth in which
life exists including land, water, and
air.
Ecological Levels of Organization
The World’s Major Land Biomes
Energy Flow Through An Ecosystem
• Sunlight is the main source of energy for life
on Earth.
• Less than one percent of the sun’s energy that
reaches the surface is used by living thing
• Autotrophs (producers) – organisms that
use either light energy or inorganic chemicals
make their own food
– Photosynthesis – process in which
organisms use light to make their own
food (sugar)
• Examples: plants, algae, some bacteria and
some protists
– Chemosynthesis - process in which
organisms use inorganic chemicals to make
food
• Examples: bacteria which live in volcanoes,
hot springs, and deep-sea vents
• Heterotrophs (consumers) – organisms that
must eat food for their energy and cannot
make their own food
– Herbivores – eat mostly plants
• Examples
– Carnivores – eat mostly animals
• Examples
– Omnivores – eat both plants and animals
• Examples
– Decomposers – break down organic
material
• Examples
• Feeding Relationships
– Food Chain – series of steps in
which organisms transfer energy
by eating or being eaten
– Food web – links all of the
food chains in an ecosystem
– Trophic Level – each step in a
food chain or food web
• What eats what? This is the order that
energy flows through an ecosystem:
– Producers
– Primary (first) consumers
– Secondary (second) consumers
– Tertiary (third) consumers
• Arrows point the direction the energy or
food flows (from food to “eater”).
A Food Web
Section 3-2
Make your own food web
Energy Pyramid
• Energy Pyramid - shows the relative
amount of energy available at each trophic
level.
• Ten Percent Rule - only about 10% of
energy available within one trophic level is
transferred to next level
– Why this inefficiency?
• Most of the energy that an organism
uses does not make it into the organism
that eats it.
• Energy in feces, energy used in
metabolism, and energy converted to
heat does not make it to the next
trophic level.
Not all of the caterpillar’s food is converted into biomass or
potential energy for a predator. So the bird that eats this
caterpillar will not get energy from the caterpillar’s feces, or
the energy that was used by the caterpillar.
Ecological Terms
• Biotic – biological (living) factors that
affect an ecosystem
• Abiotic – nonliving (physical) factors that
affect an ecosystem
Abiotic and Biotic Factors
Section 4-2
Abiotic Factors
Biotic Factors
ECOSYSTEM
Go to
Section:
Abiotic and Biotic Factors
Section 4-2
Abiotic Factors
Biotic Factors
ECOSYSTEM
Go to
Section:
• Niche – full range of physical and
biological conditions in which an organism
lives and the way the organisms uses
those conditions
Figure 4-5 Three Species of
Warblers and Their Niches
Section 4-2
Cape May Warbler
Feeds at the tips of branches
near the top of the tree
Bay-Breasted Warbler
Feeds in the middle
part of the tree
Spruce tree
Go to
Section:
Yellow-Rumped Warbler
Feeds in the lower part of the tree and
at the bases of the middle branches
Section 4-2
Interactions in Ecosystems
• Organisms not only live together in
ecological communities, but they also
constantly interact with one another.
These interactions, which include
predation and competition, help shape
the ecosystem in which they live.
Community Interactions
• Competition—an interaction in which
organisms of the same or different species
attempt to use a resource in the same place
and at the same time.
• Predation—an interaction in which one
organism captures and feeds on another
animal
• Symbiosis – a relationship in which two
species live closely together
– Three types of symbiosis:
• Mutualism = + + (both benefit)
–Examples:
• Commensalism = + 0 (one benefits,
other little or no benefit)
–Examples:
• Parasitism = + - (one benefits, other
harmed)
–Examples:
Termites have bacteria in their guts that help the termites to
digest wood. The bacteria get a nice, warm gut in which they
can live. What relationship is this?
Some orchids grow on trees to get sunlight in dark
forests. The orchid does not hurt the tree. What
relationship is this?
Remora attach to
big fish or whales
and eat the parasites
Remora that grow on the big
fish’s or whales
scales. What
relationship is this?
Remora
attached to a
big fish
1. The hookworm latches on the walls of the colon with its sharp
teeth where it feeds on blood.
2. The tapeworm is the longest parasite. A mature adult can lay one
million eggs per day.
3. Tapeworm eggs are embedded in the colon.
4. The roundworm can grow to 20 inches (50 cm) long and lay
200,000 eggs per day.
5. Pinworms migrate outside the colon during the night to lay their
eggs around the anus. This causes the nightly itching of many
unsuspecting victims.
Ticks suck the blood of animals (including people).
What relationship is this?
Mouth of a
hookworm
Hookworms live in
the intestines of
many mammals
including humans.
They suck blood
from your gut and
can make you sick.
What relationship is
this?
Ringworm (top left and
bottom right) and athlete’s
foot (top right) are both fungi
that live off of human skin.
They both cause irritation
and are very contagious.
What relationships are these?
Pseudoscorpions
hitching ride on a
fly’s leg, Costa
Rica.
Pseudoscorpions,
tiny relatives of true
scorpions, often
engage in the
practice of phoresy,
or hitchhiking. What
relationship is this?
The anemonefish lives among
the forest of tentacles of an
anemone and is protected from
potential predators not immune
to the sting of the anemone. The
anemonefish is protected from
the sting of the anomone
tentacles by a substance
contained in the mucous on its
skin.
Some consider this relationship
to be a case of mutualism,
claiming that the anemonefish
chases away other fish that
might prey on the anemone.
However this aspect of the
relationship is not well
documented.
Cycles of matter
• Unlike the one-way flow of energy, matter
is recycled within and among ecosystems
• Biogeochemical cycles pass molecules
around again and again
• The Cycles
– Water Cycle
– Carbon Cycle
– Nitrogen Cycle
– Phosphorus Cycle
The Nitrogen Cycle
Go to
Section:
The Nitrogen Cycle
• All living things need nitrogen as a nutrient.
• Nitrogen gas makes up 78% of our atmosphere
and yet animals and plants cannot use nitrogen
gas as a nutrient. So what’s an animal or plant
to do?
• How do animals get nitrogen? They eat protein!
• How do plants get nitrogen? From bacteria
that are in the soil or in the roots of some
plants.
• Plants can only use nitrogen when it is in the
form of nitrate (NO3-) or nitrite (NO2-).
• Decomposers breakdown organic material (e.g.
dead plants and animals) in the soil. Nitrogen
comes from broken down proteins and DNA.
• Some bacteria live in the soil and help to
convert nitrogen into usable forms for plants.
Plants absorb this useable nitrogen from the
soil into their roots.
• Nitrogen Fixation – when nitrogen gas is
converted into useable nitrogen by bacteria
• Some bacteria actually live inside of the roots of
certain plants (like legumes) and can fix nitrogen
in the roots.
• This is like the bacteria that live in our guts and
help us to digest food.
• Legumes include peas, beans, peanuts, soybeans,
alfalfa, and clover.
• So how is this a cycle? Denitrification – some
bacteria can convert nitrites back into nitrogen gas
which is released into the atmosphere
Root Nodules
• “Green Manure” – when farmers plant
legumes and then plow them into the
ground instead of harvesting the crop
– The legumes release nitrogen fixing
bacteria into the soil to help the next
round of crops get their nitrogen.
Mount Saint Helens
• At 8:32 Sunday morning, May 18, 1980, Mount
St. Helens erupted.
• Shaken by an earthquake measuring 5.1 on the
Richter scale, the north face of this tall
symmetrical mountain collapsed in a massive
rock debris avalanche. Nearly 230 square miles
of forest was blown over or left dead and
standing. At the same time a mushroom-shaped
column of ash rose thousands of feet skyward
and drifted downwind, turning day into night as
dark, gray ash fell over eastern Washington and
beyond. The eruption lasted 9 hours, but Mount
St. Helens and the surrounding landscape were
dramatically changed within moments.
Harry Truman (not the president)
BEFORE
AFTER
BEFORE
AFTER
Some weedy plants recover
quickly
Forest blown over
Same forest 9 years later
Same forest 14 years later
Changes in an Ecosystem
• Ecological Succession – a series of changes
in a community over time in response to natural
and human disturbances
– As changes occur, older inhabitants die out
and new organisms move in.
– Primary Succession
• Occurs where there is no soil
–After a volcanic eruption
–Bare rock exposed by glaciers moving
• Pioneer Species – the first species to
populate an area (ex. lichens)
–Lichens (a symbiotic organism
between a fungus and an alga) can
grow on bare rock.
–Lichens release chemicals that
dissolve and break down rock thus
making soil.
• Once there is soil, other organisms
come in like mosses and small plants
and animals soon follow. Why do
animals come after plants?
– Secondary Succession
• Occurs when life is removed without
destroying the soil
• Plowing, fire, deforestation, drought, etc.
can all spark secondary succession
• Occurs faster than primary succession.
Why?
Methods Of Estimating Population Size
• For stationary organisms:
– Quadrant method
• For moving organisms:
– Mark and Recapture
• Great Turtle Race
• For people:
– Census
Characteristics of Populations
• Geographic distribution
• Population Density - the number of
individuals of a population within a given
area
• Growth rate
Population Growth
• Three factors that affect population
size:
– Number of births (birthrate)
– Number of deaths (death rate)
– Number of individuals that leave
(emigration) or enter
(immigration) a population
Population Growth Curves
• Exponential Growth – highest rate of
reproduction under ideal conditions
• Logistic growth – occurs when a
population’s growth slows or stops
following a period of exponential growth
– Carrying capacity – maximum number
of individuals in a population that the
environment can support
Limiting Factors
• Limiting factors – conditions that cause
population growth to decrease
• Competition
• Disease (contagious)
• Predation
• Parasitism
• Lack of food, habitat, mates, and oxygen
• Climate
• And more…
• Predation – hunting, killing, and eating an
animal
– Example: eagles (predators) and mice (prey)
– Predation may be a limiting factor for the
prey population while food availability may be
a limiting factor for the predator
60
2400
30
1200
0
0
1955
1975
Moose
1995
Wolves
Human Population
• World Population as of August 2011
– Estimate: 6,953,111,602
• World Population as of 2050
– Projection: 9,404,251,020
• U.S. Population as of August 2011
– Estimate: 311,906,242
One birth every...................................... 7 seconds
One death every................................... 13 second
One international migrant (net) every..... 45 seconds
Net gain of one person every................. 12 seconds
• U.S. Population for 2050
– Projection:422,854,000
• A World Population Clock
• World Clock with extra data
•
Source for USA and World Pop data: http://www.census.gov/ipc/www/idb/worldpopinfo.html and
www.census.gov/population/www/popclockus.html
Human Population
Industrial
Revolution
begins
Agriculture
begins
Plowing
and
irrigation
Bubonic
plague
Natural and Human Disturbances
•
•
•
•
•
•
•
•
•
Global Warming
Ozone depletion
Nonnative species
Invasive species
Water, soil, and air pollution
Habitat destruction (fire, deforestation, etc)
Oil spills
Salinization of soil
Mining