Biotic

Interactions8.11A DESCRIBE PRODUCER/CONSUMER,

PREDATOR/PREY AND PARASITE/HOST RELATIONSHIPS

AS THEY OCCUR IN FOOD WEBS WITHIN MARINE,

FRESHWATER AND TERRESTRIAL ECOSYSTEMS

Biotic

These are the living organisms in any

given ecosystem

Animals – vertebrate or invertebrates

Plants – flowering and non-flowering

Fungi – mushrooms, molds

Micro-organisms – bacteria, protists

(see ex.)

Abiotic

biotic and abiotic factors interact in ecosystems.

organisms are dependent on the abiotic and biotic factors in their environment.

Abiotic factor examples: Sun, heat, light, temperature, rocks, soil, wind, precipitation, air, water, clouds

The factors together:

Biotic Interactions In

Ecosystems

There are several types of interactions (also known as “feeding relationships”) among organisms in ecosystems.

Other interactions are caused by competition for food and resources

Producer/consumer

Relationships

Roles within Ecosystems

Producer/autotroph – organism that

makes its own food, such as a plant

or photosynthetic alga.

Recall that in order to make their

own food, autotrophs use the sun’s

energy to convert water and carbon

dioxide in to food , a sugar - glucose.

This is the process of photosynthesis,

Roles within Ecosystems

Consumer/heterotroph - an organism that

feeds on other organisms

There are different tiers or “levels” of

consumers

Include organisms that feed only on

autotrophs, organisms that feed solely on

other heterotrophs, and organisms that

feed on both auto and heterotrophs.

Roles within Ecosystems

Primary consumer (first level consumer)

– animals that get their energy from

eating plants

These are always herbivores, but can

also be omnivores

Roles within Ecosystems

Secondary consumer (second level

consumers) – animals that get their

energy from eating other animals

Always carnivores, but also some

omnivores

Roles within Ecosystems

Tertiary consumer (top level consumers) – animals

that get their energy from eating other animals

Top carnivore (may also be omnivore like bears)

Note – there can be higher levels than tertiary, but

these are few and far between due to energy

transfer that occurs within an ecosystem

Roles within Ecosystems

Decomposer – simple organism, such as

bacteria or fungus, that breaks down dead

organisms and waste, returning important

nutrients to the environment

How do these various roles

come about? Biotic factors include food chains and webs

where some organisms might share food sources setting up competition

Many organisms are adapted to survive in ecosystems by resource partitioning – they feed at different times of day or at different levels in the same tree

Carrying capacity – the number of animals that can obtain food, shelter, and water from the environment in a given area; the ability of an environment to support its animal population

CompetitionCompetition - occurs when

organisms try to make use of the same limited resources

Competition occurs between:

Members of the same species

Among species with similar niches

They are competing for abiotic or biotic resources

How do these examples to the right compete?

How does a “niche” come

about?

A niche is - an organism’s particular role, or

how it fits into an ecosystem

A niche is created when species compete

Many organisms are adapted to overcome

competition by resource partitioning:

They feed at different times of day

Or at different levels of the same tree

Words to Know

Resource partitioning- helps competing

species share a resource and develop

a niche for themselves in an

ecosystem.

For example:

Species of birds will feed at different

times of day

Or at different levels of the same tree

Warbler example:

Carrying Capacity:

Carrying capacity is the largest number of

individuals of a population that a given

environment can support. Living within the

limits of an ecosystem depends on three

factors:

the amount of resources available in the

ecosystem,

the size of the population, and

the amount of resources each individual is

consuming (using).

Carrying Capacity: An example of a situation in which the carrying

capacity of an environment is exceeded is the

example of deer in North America.

After the widespread elimination of wolves – the

natural predator of North American deer – the deer

reproduced until their need for food plant species

exceeded the environment’s ability to regenerate

their food plants. In many areas, this resulted in large

numbers of deer starving until the deer population

was severely reduced.

Predator/Prey

Relationships

Predation

Predation - An interaction in which one

organism hunts and kills another for food

Hunter – predator

Gets eaten - prey

Predator Adaptations

Predators have adaptations that help them

catch and kill their prey.

Cheetahs can run very fast to catch prey

Jellyfish have poisonous tentacles to

paralyze prey

Owls have big eyes to see at night

Prey Adaptations

Prey have adaptations to help

them avoid predators

Camouflage

Protective coverings

Warning coloring

Mimicry

False coloring

Effects on Predation on

Population Size

Predation can have a major effect on

population size

If predators are very effective, the

result is a decrease in the prey

population

In turn, a decrease in the prey

population will result in a decrease in

the predator population

Parasite/Host

Relationships

Symbiosis

A close relationship between

two different species that

benefits at least one of the

species

Benefits of Symbiosis:

Food

Transportation

Cleaning

Protection/Shelter

Reproduction

There are three types of

symbiotic relationships:

Mutualism

Both species benefit

Remora fish clean

sharks of external

parasites and in

return receive free

rides and food.

Giraffes and

oxpecker birds

Commensalism

One species benefits and the other is unaffected –

Ex. Clown fish are protected from predators by sea anemones’ poisonous tentacles. The relationship does not affect the sea anemone negatively or positively.

Barnacles and whales

Parasitism

One gains considerably

at the expense of the

other

Host – the organism that

the parasite lives on or

in – it will be harmed

Parasite – the organism

that benefits

Reef Symbiosis