ECOSYSTEMEcology, Biomes, Symbiosis

ECOSYSTEM

An ecosystem is formed by the interactions between all living and non-living things

How do living and non-living things interact in an environment?

The earth can be divided into layers:

Atmosphere:Trophosphere – goes up 11 miles,

greenhouse contains ozone

Stratosphere – ozone layer, filter out harmful UV rays

Hydrosphere: all the ice, H2O, and H2O vapor

Lithosphere: the land (crust/mantle)

What sustains life on earth?

The one-way flow of high-quality energy

The cycling of matter or nutrients

Gravity

Allows the planet to hold onto its atmosphere

Causes the downward movement of nutrients

Ecosystem Function

1. Energy flow in an ecosystem is

represented by a food web.

2. Nutrients are recycled within an ecosystem.

Water * NitrogenCarbon * PhosphorusOxygen * Sulfur

Ecosystems:

Fundamental CharacteristicsStructure:

Living (biotic)

Nonliving (abiotic)

Process:

Energy flow

Cycling of matter (chemicals)

Change:

Dynamic (not static)

Succession, etc.

ABIOTIC components:

Solar energy provides practically all the energy for ecosystems.

– water

– temperature

– wind

– sunlight

– soil

BIOTIC componentsThe biotic components of an ecosystem can be classified according to their mode of energy acquisition.

Ecology is

The study of the distribution and

abundance of organisms,

AND

the flows of energy and materials

between abiotic and biotic

components of ecosystems.

Organism

Organism

An organism is an individual living thing,

such as an alligator.

Organism

Organism

PopulationPopulation

• A population is a group of the same

species that lives in one area.

Organism

Organism

Population

Population

Community

Community

• A community is a group of different

species that live together in one area.

Organism

Organism

Population

Population

Community

Community

Ecosystem

Ecosystem

• An ecosystem includes all of the organisms as

well as the climate, soil, water, rocks and other

nonliving things in a given area.

Organism

Organism

Population

Population

Community

Community

Ecosystem

Ecosystem

Biome• A biome is a major regional or global community of

organisms characterized by the climate conditions

and plant communities that thrive there.

Observation is the act of carefully watching something over time.

Observations of populations can be done by visual surveys.

Ecological research methods include

observation, experimentation, and modeling.

– Direct surveys for easy to spot species

employ binoculars or scopes.

– Indirect surveys are used for species

that are difficult to track and include

looking for other signs of their presence.

Modified from: General Ecology, by David T. Krome

Trophic level: All the organisms that are the same number of food-chain steps from the primary source of energy

Niche vs habitat

A habitat is wear an organism lives. The habitat must

provide a source of food, water and shelter for the

organism.

Niche is the role of the organism. This is largely to do

with the trophic level of the organism.

For example: plants produce food for the rest of the

food chain. Tigers keep herbivore populations under

control.

Trophic Levels

A trophic level is the position occupied by an organism in a food chain.

Trophic levels can be analyzed on an energy pyramid.

Producers are found at the base of the pyramid and compromise the first trophic level.

Primary consumers make up the second trophic level.

Secondary consumers make up the third trophic level.

Finally tertiary consumers make up the top trophic level.

Trophic Levels Found on an Energy Pyramid

The greatest amount

of energy is found at

the base of the

pyramid.

The least amount of

energy is found at

top of the pyramid.

Pyramid of

biomass

Energy and biomass pyramids

BiomassEnergy is sometimes considered in terms of

biomass, the mass of all the organisms and organic

material in an area.

There is more biomass at the trophic level of

producers and fewer at the trophic level of

tertiary consumers. (There are more plants on Earth

than there are animals.)

Bio=life Mass=weight

Bio + Mass = Weight of living things within an

ecosystem.

Food Chains The producers, consumers, and decomposers of each

ecosystem make up a food chain.

There are many food chains in an ecosystem.

Food chains show where energy is transferred and

not who eats who.

Example of a Food Chain

Food Chains

Trophic levels in food chains

Be able to give an example of each!

Primary producers (autotrophs)

Primary consumers (herbivores)

Secondary consumers (carnivores)

Tertiary consumers (top carnivores)

Decomposers

Detrivores

Scavengers

Ecosystem Structure:

the living components of an ecosystem

The roles of organisms in an ecosystem:

Producer (autotrophs): make food; plants, algae

Consumer (heterotrophs): eat other organisms

Decomposer: eat dead organic matter; bacteria

and fungi

Role of Organisms

Scavengers – feed on dead organisms (vultures, flies, crows, lobsters)

Detritus feeders – organisms that extract nutrients from fragments of dead organisms into more simple organic waste (termites, earthworms, crabs)

Decomposers – organisms that digest parts of the dead organisms into simplest chemicals (bacteria, fungi)

Role of organisms

Classes of Consumers

Herbivore – primary consumer – eats plants

Carnivores – secondary–meat eaters; eat herbivores

Tertiary – feed on carnivores

Omnivores – eat plants/animals

Food Webs All the food chains in an area make up the food web of the area.

Food web of a hot spring

Food webs

Energy Transfer

POWER of 10

A keystone species is a species that has an unusually

large effect on its ecosystem.

keystone

Keystone species form and maintain a complex web of life.

creation of

wetland

ecosystem

increased waterfowl

Population

increased fish

populationnesting sites

for birds

keystone species

Limiting factors

An abiotic factor can limit the population size if there is too much or too little of it. Even if there is the right amount of other factors

Examples to consider:

Sunlight

Precipitation

Salinity

Nutrients in the soil

Parasitism

Parasitism is the

situation where one

organism benefits

while the other is

harmed.

A + / - relationship.

Think of a friendship

where you might feel

used by your friend. Parasitic Isopod on fish

Bedbugs Bedbugs are small,

nocturnal parasites that come out of hiding at night to feed on unsuspecting humans. They feed exclusively on blood! Their bites often result in an allergic reaction.

Parasitism: one benefits, one is harmed

Taenia worm in human eye

Worm infects

human blood

stream

Human may go

blind

Commensalism

Commensalism is whereone species benefits whilethe second speciesremains unaffected.

A + / 0 relationship

Think of a friendship where one of the friends benefits while the other doesn’t change.

Barnacles adhering to the skin of a whale

Commensalism: one benefits, one is unaffected

Cattle with cattle egrets

Cattle stir up

insects as

they eat

grass

Egrets hang

around and

eat insects

Neutralism is the situation where both species remain unaffected.

A 0 / 0 relationship.

Think of someone you sit beside but never show any emotional either positive or negative.

Neutralism

Neutralism the most common type of

interspecific interaction. Neither population

affects the other. Any interactions that do occur

are indirect or incidental.

Example: the tarantulas living in a desert and

the cacti living in a desert

Competition is where neither species benefits.

A - / - relationship.

Think of someone whom you are constantly at battle with.

COMPETITION: Scramble (Indirect) vs. Contest (Direct)

Scramble: mutual use of limited resource

-Most plant competition is of this form

Contest: interact directly (direct aggression or display)

Competition can be defined as an interaction

between organisms or species, in which

the fitness of one is lowered by the presence of

another.

Limited supply of at least one resource (such

as food, water, and territory) used by both is

required. Competition is one of many interacting

biotic and abiotic factors that

affect community structure

intraspecific competition -

Competition among members of

the same species

interspecific competition.

competition between individuals of

different species is known as

Amensalism between two species involves one

impeding or restricting the success of the other while the other

species has no effect on it.

Do you know that there are organisms that may live

together only for sometime

because one species secrete a toxic or lethal substance that

could kill the other species?

Are you familiar with some of them? A certain species of

Artemisia (damong maria) secrete

a substance that can kill the grasses that may grow around

them. This is an example of

amensalism.

It is a type of symbiosis. Usually this occurs when

one organism exudes a chemical compound as part of its

normal metabolism that is detrimental to another organism.

Damong Maria

The bread mold Penicillium is a common example of this;

penicillium secrete penicillin, a chemical that kills bacteria.

A second example is the black walnut tree (Juglans

nigra), which secrete juglone, a chemical that harms or

kills some species of neighbouring plants, from its roots.

This interaction may still increase the fitness of the non-

harmed organism though, by removing competition and

allowing it access to greater scarce resources. In this

sense the impeding organism can be said to be negatively

affected by the other's very existence, making it a +/-

interaction.

A third simple example is when sheep or cattle make

trails in grass that they trample on, and without realizing,

they are killing the grass.

Since one of the characteristics of fungi is that

they are unable to produce their own food by

photosynthesis, due to the lack of choloroplasts,

they obtain their food from other organisms. They

also do not have mouths to take in food as

animals do, therefore they absorb food through

their plasma membranes and cell walls. One of

the types of such heterotrophic food intake

methods is saprophytism

Saprophytism

Effects and examples

They break down wastes from dead organic matter

and thereby enabling the constituent materials to be

available for reuse by other organisms within the

ecosystem.

dry rot, which occurs in wooden houses, and other

wooden structures, causing the wood to deteriorate

and the structure to fall apart

Cannibalism

Eating species of the same kind.

Example: Human (Holocaust)

Spider

dog eating puppies

Cooperation Helping same kind of organisms or organisms of different

kind to get food.

Example: Ants in a colony

honeybee colony where the member

carry out and follow specific task

rigidly and work together for benefit

of the group

X

Y Type of interaction

0 0 Neutralism

- 0 Amensalism

+ 0 Commensalism

- - Competition

+ + Mutualism

+ - Predation orParasitism

Terminology

Herbivory: an animal consuming plant

material

4 kinds of herbivores:

Grazers (aka folivores) consume leafy material

Browsers consume woody material and bark

Granivores consume seeds

Frugivores consume fruit