Competition, Predation,

Symbiosis, Mutualism,

Commensalism, or Parasitism

Population – group of individuals of the same species

living in the same area, potentially interacting

Community – group of populations of different species

living in the same area, potentially interacting

What are some ecological interactions?

Why are ecological interactions important?

Interactions can affect distribution and abundance.

Interactions can influence evolution.

Think about how the following interactions can affect

and evolution.

Symbiosis – two species live together can include

parasitism, mutualism, and commensalism

Commensalism

Commensalism is a relationship between

two living organisms where one benefits

and the other is neither harmed nor

helped.

Commensalism – one species receives a benefit from

another species enhances fitness of one species; no

effect on fitness of the other species

The clownfish lives among the forest

of tentacles of an anemone and is

protected from potential predators.

Some birds live among cattle to eat the

insects stirred up as they walk. One

example are egrets who hunt for

insects near a grazing animal's mouth.

One animal attaching itself to another

for transportation such as barnacles

attach to shells or whales or a shrimp

riding on a sea slugs.

barnacles on whale’s tail and clam shrimp riding on a sea slug

One species uses a second

organism for housing such as small

mammals or birds that lives in holes

in trees or orchids which live in trees.

Orchid in rainforest Venezuela

Parasitism

One organism, usually physically smaller of

the two (the parasite) benefits and the

other (the host) is harmed

Parasitism – one species feeds on another enhances

fitness of parasite but reduces fitness of host

Ticks and fleas that live in a host

animal's fur bite the animal and

drink its blood are parasites.

Insects such as mosquitoes

feeding on a host are parasites.

Vines such as Kudzu growing on Trees

Tapeworm or Hookworms living in

Host's Gut

The roots of the Owl Clover are

partly parasitic on the roots of other

desert wildflowers.

Mutualism

Both species benefit from the interaction.

Mutualism – two species provide resources or services

to each other enhances fitness of both species

Flowers and their Pollinators

(examples: Bees and

hummingbirds gather nectar and

spread pollen.)

Birds and mammals eat berries and

fruits while the plant benefits by the

dispersal of it seeds.

Algae and Fungi > Lichen - Alga

gets water and nutrients from the

fungus and the fungus gets food

from the algae.

Cleaners eat insect pests from the skin

of animals. (ex: Egyptian plover cleans

giraffes and buffaloes)

Many herbivores such as cows, sheep,

deer, horses and rabbits depend on

bacteria that live in their stomachs to

break down the plant material.

Coral Reefs- The corals get food

and the algae get protection.

Predation

one eats another (Herbivores eat plants.

Carnivores eats animals.)

Predation – one species feeds on another enhances

fitness of predator but reduces fitness of prey

herbivory is a form of

predation

Competition – two species share a requirement for a

limited resource reduces fitness of one or both species

Competition between the

same species is

called intraspecific

competition.

Many birds of the same

species compete for the

best nesting grounds.

In cases when food or

water is scarce, members

of the same species will

compete for food in order

to survive.

Competition between

different species is

called interspecific

competition.

Different species often

compete for space, food,

or water. For example the

lion and the hyena both

compete for zebra.

Organizing ecological interactions

effect on species 1

effect on

species 2

+ 0 -

+

0

-

mutualism

predation

herbivory

parasitism

predation

herbivory

parasitism

commensalism

commensalism

competition

competition

competition

http://youtu.be/D1aRSeT-mQE