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 – eats decaying plant and animal matter Fungus, bacteria

Scavenger – eats leftovers Coyote, 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

Producers

Tertiary consumers

Secondary consumers

Primary consumers

Quaternary consumers can

exist in some food chains above the

tertiary consumers.

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.

1,000,000 J of sunlight

10,000 J

1,000 J

100 J

10 J

Producers

Tertiary consumers

Secondary consumers

Primary consumers

10%

10%

10%

10%

Solar energy is converted to chemical

energy!

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: (+,0)

One species benefits, the other is not affected Parasitism: (+,-)

One 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.

As predators increase, prey decrease.

As prey decrease, predators decrease.

As predators decrease, prey increase.

PreyPredator

Number

Time

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 S-shaped

The human

population grew like

this following

the introducti

on of sanitation

and medicatio

n!

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 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. This effects aquatic ecosystems especially

due to more links in the food chain.

great blue heron

sunfish

mayfly nymph

algae

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