I. Ecology the study of interactions between organisms and

their environments What do you mean by environment?

The environment is made up of two factors:

Biotic factors- all living organisms inhabiting the Earth

Abiotic factors- nonliving parts of the environment (i.e. temperature, soil, light, moisture, air currents)

Organism

Population

Community

Biosphere

Ecosystem

Organismany unicellular or multicellular form exhibiting all of the characteristics of life, an individual.

• The lowest level of organization

Populationa group of organisms of one species living in the same place at the same time that interbreed and compete with each other for resources ( food, Water, mates, shelter)

Communityseveral interacting populations that inhabit a common environment and are interdependent.

Ecosystempopulations in a community and the abiotic factors with which they interact

•ex. marine, terrestrial

Biospherelife supporting portions of Earth composed of air, land, fresh water, and salt water.

•The highest level of organization

•The Biospher is composed of many Biomes

II. Land Biomes Biome-

geographic areas that have similar climates and ecosystems

The 6 most common biomes are:

TundraTaigaTemperate

Deciduous ForestTropical Rain ForestGrassland Desert

III. Habitat vs. Niche• Habitat- the place in which an organism lives

out its life (address)• Niche - the role a species plays in a community

(job)– A niche is determined by a limiting factor.

• Limiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment.

– Examples of limiting factors-• Amount of water, food, Temperature

“The ecological niche of an organism depends not only on where it lives but also on what it does. By analogy, it may be said that the habitat is the organism's ‘address’, and the niche is its ‘profession’, biologically speaking.”

IV.Feeding Relationships There are 3 main types of feeding

relationships Producer- Consumer Predator- Prey Parasite- Host

1. Producer- all autotrophs (plants), they trap energy from the sun to make food (sugar).

Bottom of the food chain

2. Consumers- all heterotrophs: they ingest food containing the sun’s energy

Herbivores Carnivores / Scavangers Omnivores Decomposers

Herbivores Eat plants Primary consumers Prey animals

Carnivoreseat meatPredatorsHunt prey animals for food.

ScavengersFeed on carrion, dead animals

Omnivoreseat both plants and animals

DecomposersBreakdown the complex compounds of dead and

decaying plants and animals

V. Symbiotic Relationships

– Symbiosis- two species living together

• 3 Types of symbiosis:

1. Commensalism

2. Parasitism

3. Mutualism

VI.Trophic LevelsEach link in a food

chain is known as a trophic level.

Trophic levels represent a feeding step in the transfer of energy and matter in an ecosystem.

Food chain simple model that

shows how matter and energy move through an ecosystem

Producers- Autotrophs

Primary consumers- Herbivores

Secondary consumers-small

carnivores

Tertiary consumers-

top carnivores

E

N

E

R

G

Y

Food web shows all possible feeding relationships in a

community at each trophic level Represents a network of interconnected food

chains

Food chain Food web(just 1 path of energy) (all possible

energy paths)

VII.Population Dynamics

Three Key Features of Populations

1. Size

2. Density

3. Dispersion

• Clumped

• Even/Uniform

• random

1. Size: number of individuals in an area

• Growth Rate: How many individuals are born vs. how many die

– Birth Rate (natality) - Death Rate (mortality) = rate of natural increase POST-

REPRODUCTIVE

REPRODUCTIVE

PRE-REPRODUCTIVE

2. Density: measurement of population per unit area or unit volume

• Pop. Density = # of individuals ÷ unit of space

• 4 Factors that affect density1. Immigration- movement of individuals into

a population 2. Emigration- movement of individuals out of

a population 3. Density-dependent factors- Biotic factors

in the environment that have an increasing effect as population size increases– Ex. Disease, competition

4. Density-independent factors- Abiotic factors in the environment that affect populations.– Ex. temperature, storms, habitat destruction,

drought

Immigration

Emigration

Birth MortalityPopulation+

+

-

-

Factors That Affect Future Population Growth

Other factors that affect population growth

Limiting factor any biotic or abiotic factor that restricts the

existence of organisms in a specific environment. Amount of water, food, temperature, predation

Many organisms

present

Few organisms present

Few organisms present

None None

Limiting Factor- Zone of Tolerance

Carrying Capacity the maximum

population size that can be supported by the available resources

There can only be as many organisms as the environmental resources can support

Carrying Capacity (k)

N

u

m

b

e

r

Time

J-shaped curve (exponential growth)

S-shaped curve (logistic growth)

VIII. Nutrient Cycles• Cycling maintains homeostasis (balance) in

the environment.• 3 cycles to investigate:

1. Water cycle2. Carbon cycle3. Nitrogen cycle

Water cycle –Evaporation, transpiration, condensation,precipitation

Carbon cycle -Photosynthesis and respiration cycle carbon and oxygen through the environment.

Nitrogen cycle - •Atmospheric nitrogen (N2) makes up nearly 80% of air. •Organisms can not use it in that form.•Lightning and bacteria convert nitrogen into usable forms.•Nitrogen fixation-convert atmospheric nitrogen (N2) into ammonium (NH4

+) which can be used