What is Ecology?

• Study of the relationship between organisms AND between organisms and their environment

Organization of the Living World

Biosphere

Ecosystem

Community

Population

IndividualSmallest

to

Largest

Population

All the members of the same species that live in the same area

Community

All populations of organismsliving in the same place

Ecosystem

All biotic and abiotic factorsin a particular environment

BIOSPHERE

All regions of the earth where life can exist

Abiotic vs. Biotic Factors

Abiotic (nonliving)

- soil, temperature, sunlight, water, gases, minerals, etc.

Biotic (living)

- Any living thing (all depend on abiotic factors for survival)

Habitat vs. Niche

Habitat - an organism’s environment (ex. A forest)

Niche - an organism’s role in its environment (ex. Producing oxygen (plants))

Niche of Organism A

Niche of Organism B

Competition

When niches of 2 organisms overlap, competition results

Symbiotic Relationships

Relationship between two organisms in which one organism benefits

Symbiotic Relationships

• Mutualism - both organisms benefit from relationship (+,+)

• Parasitism - one organism benefits at the expense of the other (+, -)

• Commensalism - one organism benefits while the other is unaffected (+, 0)

Energy Flow through an Ecosystem

Food Chains and Food Webs

Energy Flow

• The source of all energy on earth is the sun

• The sun’s energy is trapped by plants in photosynthesis and transformed into carbohydrates

• Energy is measured in calories (kcal)

How do organisms get energy? The trophic levels

• Producers (autotrophs)

• Consumers* (heterotrophs):

- primary (herbivores - eat only producers)

- secondary (eat primary consumers)

- tertiary (eat secondary consumers)

*A consumer can be all three types at the same time (omnivore)

Food Chains and Webs

• Show the path of energy through an ecosystem

• Arrows follow the direction of energy flow

• All food chains and webs have producers at the base

Food Webs

• Food webs show many food chains and how they are connected to each other

• Food webs are more accurate representations of the true relationships between organisms

Example of a food web

Energy Flow in a Food Web

• At each step in the food chain, 90% of the energy is lost as heat

• Each organism in the chain receives 10% of the energy from the organism it consumes (except for producers which get their energy from the sun)

In the diagram above, only 10%of the available energy is passedon to each trophic level

Pyramid of Energy and Biomass

Biomass - total amount of living tissue

Pyramid of Energy and Biomass

producers

Primary consumers

Secondary consumers

Tertiary consumers

Decr

easi

ng b

iom

ass

Decr

easi

ng e

nerg

y

Pyramid of Energy and Biomass

producers

PC

SC

TCHEAT

1000 calories

100 calories

10 calories

1 calorie

Cycling of Matter vs. Energy

• Matter is recycled as it passes through any ecosystem.

• Energy is not recycled. It is used up by each organism

Water cycle

evaporationprecipitation

Transpiration(excess water exits through the leavesas water vapor)

runoff

Condensation to form clouds

Uptake throughroots

The Water Cyclegroundwater

Water vaporRises and cools

CO2

(air)

ConsumersProducersmake Carbohydrates

(photosynthesis)

photosynthesis respiration

decomposers

Death &

decay

Death

& d

ecayre

spir

ati

on

Fossil fuels (oil, coal)

Millions of years, high pressureand temperature

Factories, cars

Use

d a

s en

ergy

for

combustion

CARBON CYCLE

respira

tion

N2

(gas)

Nitrates (in soil)Ammonia(in soil)

Bacteria change ammonia into

N2 fixing bacteriachange N2 gas into

plants

Used by

Consumers

Eaten by

Ammonia (in soil)

Dec

ompo

sition

Aft

er d

eath

(by

Dec

ompo

sers

)

Denitrifying bacteriaChange nitrates to N2 gas

NITROGEN CYCLE

Decomposition

After death

Bacteria changeammonia into

Phosphate(soil)

Consumers

Producers

Eaten byUptake through roots Die & decompose

Aquatic producers and consumers die

Body ofwater (lakes,oceans, etc.)

PHOSPHORUS CYCLE

Phosphates in soilseep into streams

Rocks & sediments

Die & decompose