Transcript Community Interactions

Community Interactions
Chapter 40
Habitat
 Place
where you would normally find
an organism. It is characterized by
the temperature, physical features,
chemical features, and other species
living in it.
 Directly or indirectly all of the
species in one will associate with one
another as a community.
Community
 Each
organism within a community has
a sum of activities and relationships
in which it engages to secure and use
the resources necessary for survival
and reproduction.
 This is an organism’s niche.
Species Interactions
Neutral relationships – where organisms do
not affect each other directly. Indirectly
they may affect each other. Example:
Canadian lynx and grass.
 Commensalism – directly helps one organism
without affecting the other.
Example: Birds use trees for roosting.

Species Interactions cont…

Mutualism – interacting species both
benefit from the association.


Example: Flowering plants and pollinators.
Obligatory – individuals of one species
cannot grow or reproduce without the
other.

Example: Yucca plants cannot be pollinated by
anything besides a yucca moth.
Competition
 Disadvantages
flow both ways between
species.
 While one organism may be the winner
of the competition, it will still be injured
in the process.
Predation

Where one animal feeds upon another.
Predators feed on prey, but do not take up
residence on or in them.


1. Many predator and prey relationships arose
by coevolution, where two species exert
selection pressures on each other because of
close ecological interaction.
2. These relationships depend on carrying
capacity, the maximum number of individuals
that resources can maintain indefinitely.
Parasitism
 One
organism takes up residence in or
on another living organism called the
host.
 The parasite will feed upon the
tissues of the host, and may or may
not cause death. Parasites drain hosts
of nutrients causing a weakened
condition.
 This
weakened condition can make the
host an appealing candidate for
predation, but a less than appealing
candidate for reproduction.
 Natural selection tends to favor a
parasitic relationship that does not kill
the host, and allows the parasite to
reproduce.
Types of Parasites
 Ectoparasites
– live on host’s surface.
 Endoparasites – live inside a body.
 Microparasites – small parasites such
as bacteria, viruses, protozoans, and
sporozoans.
 Macroparasites – large parasites such
as flatworms, roundworms, fleas, and
ticks.
Competitive Interactions
Intraspecific – competition of organisms
within a species.
 Interspecific – competitions among
different species.
 Competitive Exclusion – two species
requiring identical resources cannot
coexist indefinitely.
 Resource partitioning – subdividing of
resources that let species coexist

Defense Mechanisms
 Camouflage
–
adaptations in
form, coloring,
pattern, or
behavior that
help organisms
blend in to their
surroundings.
Warning Coloration
 Conspicuous
patterns that
warn predators
to stay away.
Example:
Skunks.
Mimicry

Many prey bear
resemblance to
dangerous
organisms. One
species serves as a
mimic to the other,
more dangerous
species.

Viceroy on left,
Monarch on right
Ecological Succession
A community develops in sequence, from
pioneer species (opportunistic colonizers of
vacant habitats) to an end array of species
that remain in equilibrium over some region.
 More competitive species will replace the
beginning species until the array of species
stabilizes and results in the climax
community.

Primary Succession
 When
pioneer species colonize a
barren habitat.
 Generally, these species are small
plants with brief life cycles. Once
established, the pioneers improve the
conditions of the area and
replacement species can enter.
Secondary Succession
A
disturbed area in a community
recovers and moves toward the
climax state.
Instability
 An
outcome of forces that lead
to an uneasy balance is called
community stability.
 If these forces are disturbed, it
can hurt the growth of some
populations.
 If
the instability is great enough,
the community can change in ways
to help its survival.
 If a species cannot adapt, it may
become extinct.
Works Cited
 www.naturalsciences.org/
images/skunk.jpg
 static.howstuffworks.com/ gif/animalcamouflag
 www.ci.san-luis-obispo.ca.us/
naturalresources