Ecosystems include all populations in an area and everything that affects them. Populations interact with their environment through limiting factors that control their size and carrying capacity. Communities consist of all species in an area that interact through competition for resources, predator-prey relationships, and adaptations like camouflage or group behavior. Symbiotic relationships involve close associations between species that can be mutually beneficial, benefit one species, or involve parasitism.

1. Ecosystems & Types of
Interactions
Ecosystems – It includes all of
the populations that live in an
area and everything that affects
them.

2. Interactions with the Environment
 Limiting Factors – limits the size of a
population. Ex. – Food becomes a
limiting factor when a population
becomes so large that there is not
enough food.
 Any resource can be a limiting factor,
ex. Habitat, food, space, mates

3. Interactions with the Environment
 Carry Capacity – The largest
population that can live in the same
area for a long time.
 After a population grows larger than
the carry capacity, limiting factors
cause the population to get smaller.
Ex. Rainy seasons affecting plant
growth.

4. Interactions with the Environment
 Community – All the species in an
area.
 There are 4 different ways
organisms in a community interact
with each other.

5. Interactions with the Environment

 Competition – When two or more individuals or
populations try to use the same limited
resource. Ex. Food, water, sunlight, etc.
 Competition can also occur within populations.
Ex. – Elk in Yellowstone National Park compete
with each other for the same food plants and
for living space.
 Competition can also occur between
populations of different species. Ex. Several
kinds of trees are competing for sunlight.

6. Interactions with the Environment
 Predator and Prey – Animals
that are eaten are the prey.
Predators are the animals
that eat the prey.
 Predator adaptations –
Predators must have a
adaptations that enable
them to be able to catch
their prey. Ex. – Cheetah
runs fast, Goldenrod spider
camouflage.

7. Interactions with the Environment
 Prey Adaptations – To
avoid becoming prey,
organisms can
 run away – Ex. Rabbits
 stay in groups – Ex. Small
fish, antelopes, buffaloes
 camouflage themselves -
flounder
 poisonous- fire
salamanders

8. Symbiosis
 Symbiosis is a close, long term
association between two or more
species that can be helped, harmed
or unaffected by the relationship.
1. Mutualism – When both organisms are
helped. Ex. Clownfish and the Sea
Anemone
 2. Commensalism – When one
organism is helped and the other is
neither helped nor harmed. Ex. Sharks
and Remoras
 3. Parasitism – When one organism is
helped and the other is harmed. Ex.
Dogs and Ticks