Download Unit 2: Cytology

UNIT 11: ECOLOGY
Union Academy Charter School
Ecology

Ecology is the study of interactions among
organisms and their environment.
Obtaining food

Autotrophs: make their food
 Producers
 Plants,

algae, phytoplankton
Heterotrophs: eat their food
 Decomposer
 Fungus,
bacteria
 Scavenger
 Coyote,
– eats decaying plant and animal matter
– eats leftovers
vulture, hyena
 Herbivore
– eats plants
 Carnivore – eats animals
 Omnivore – eat both plants and animals
Energy transfer – energy pyramid

Trophic levels: levels of feeding in a community
Quaternary consumers can
exist in some food chains
above the tertiary
consumers.
Tertiary
consumers
Secondary consumers
Primary consumers
Producers
Energy transfer – ecological efficiency

As the levels increase, 90% of energy is lost as heat!
 10%
rule: only 10% of energy passes to the next level.
Tertiary consumers
10 J
10%
Secondary consumers
Solar energy is
converted to
chemical energy!
100 J
10%
Primary consumers
1,000 J
Producers
10,000 J
1,000,000 J of sunlight
10%
10%
Food chains and food webs
Food chains are a series of steps of energy transfer in an
ecosystem (similar to an
energy pyramid).
 Food webs show all
possible food chains
in an ecosystem.

Relationships within a community

Symbiotic relationships: two species live closely together.
 Mutualism:
 Both
(+,+)
species benefit
 Commensalism:
 One
species benefits, the other is not affected
 Parasitism:
 One


(+,0)
(+,-)
species benefits the other is harmed
Can lead to death
Predator/prey: (+,-)
 One
species benefits and the other is killed
 Technically
not symbiotic because they are not “living” together.
Predator/prey relationship

Predator/prey populations go up and down in
response to one another.
Prey
Predator
Number
Time
As predators increase, prey decrease.
As prey decrease, predators decrease.
As predators decrease, prey increase.
Population growth curves

Populations grow exponentially when resources are unlimited.


Biotic potential – maximum reproductive capacity under optimal conditions.
Populations grow logistically once a resource becomes limited (limiting factor – ex.
water, food, space).

Carrying capacity: maximum population size of the species that can be supported
indefinitely. Dynamic equilibrium – populations fluctuate around carrying capacity.
J-shaped
The human
population
grew like this
following the
introduction of
sanitation and
medication!
S-shaped
Population growth curves

A variety of factors can limit the growth of populations.
 Density-dependent
limiting factors – depends on population
size.
 Competition
 Predation
 Disease
/ parasites
 Land, food, water etc.
 Density-independent
limiting factors – does not depend on
population size.
 Natural
disasters (earthquake, flood, tornado, forest fires etc.)
 Long term change in weather
Human impact – acid rain

Acid rain: air pollutants released by burning coal and
other fossil fuels combine with water vapor and fall to
earth.
 Results
in rain
10X more
acidic than
normal.
 Harms plants
and infrastructure
and depletes soil
of nutrients.
NC example: fir trees dying in Carolina mountains.
Human impact – ozone depletion


The ozone layer is a layer of O3 gas that protects us from
harmful UV radiation.
Chlorofluorocarbons (CFCs) are depleting the ozone layer.
 Found
in aerosol cans, coolants, solvents, and plastic foam.
 Production
has stopped but CFCs take a very long time to break
down and are still damaging the ozone layer.
Human impact – global warming

Global warming/the greenhouse effect/climate change: Greenhouse
gasses like CO2 and methane (CH4) released into the atmosphere does
not allow sunlight to escape, causing the earth to become warmer.
Human impact – biological magnification

great blue heron


sunfish
Some chemicals can not be broken down
by decomposers and end up in the bodies
of organisms that can’t excrete them.
Biomagnification: Buildup of chemicals
in the tissue of an organism.
Bioaccumulation: Chemicals become
more concentrated as they move up the
food chain.

mayfly nymph
algae
This effects aquatic ecosystems especially
due to more links in the food chain.
Human impact – invasive species

Invasive species -species that are not native to the
ecosystem
 Often
have no natural predators to
maintain population control.
 Kudzu
into the USA
 Zebra mussels in the Great Lakes
 Black rats in Europe and USA
 Burmese pythons in the Everglades