Community Ecology

1
Community Ecology

• Relationships Between Organisms
• AP Biology

2
Ecological Niches

• A species' niche includes
• Habitat - where it lives in the ecosystem
• Relationships - all interactions with other
  species in the ecosystem
• Nutrition - its method of obtaining food

3
Competition

• Competition when two species compete for the
  same resource
• Competition can lead to competitive exclusion or
  resource partitioning

4
Competitive Exclusion

• Competitive Exclusion Theory
• 2 species cannot occupy the same niche
• If 2 species occupy the same niche, then they
  will compete until one eliminates the other
  (becomes extinct)

5
Resource Partitioning

• If one species niche is modified through natural
  selection, then it will be able to coexist with
  the other species (that it competed with before).
• niche differentiation
• Modified use of resources

6
Character Displacement

• Is evidence of previous competition between
  species
• Allopatric Speciation speciation that occurs in
  species that are geographically isolated from
  each other
• Sympatric Speciation speciation that occurs in
  species that live in the same area

7
Character displacement

• How does the diagram show evidence of
  competition?
• When the populations live together, character
  displacement occurs in order for the populations
  to co-exist (sympatric speciation)

8
Animal Defenses Aposematic coloring
Coloring or markings to warn off predators
9
Animal Defenses Cryptic coloration
Coloring that disguises an animals shape
10
Animal Defenses Batesian Mimicry
A species mimics a successful species but lacks
the actual attribute pretending to be harmful
harmful
Not harmful
Scarlet king snake
11
Müllerian Mimicry
A species resembles another successful (harmful)
species and shares the attribute (is also harmful)
Monarch butterfly
Viceroy butterfly
12
Plant Defenses Against Herbivory

• Thorns and spines
• Glandular hairs
• store and secrete toxins
• Deposition of crystals in plant tissues
• makes tissues tougher
• Chemical compounds
• May be distasteful or toxic to animals
• May cause abnormal development in animals

Images taken without permission fron
http//www.ext.vt.edu/news/periodicals/cses/1998-0
2/Glandular_hair_leaf_72dpi.JPG and
http//fm2.fieldmuseum.org/plantguides/jpgs/LOGA-s
try-toxi-pan-2735.jpg
13
Summary of Species-Species Interactions
Competition -/-
Predation /-
Herbivory /-
Parasitism /-
Disease (Pathogen) /-
Mutualism /
Commensalism /0
14
Keystone Species

• species that has a strong influence on its
  ecosystem.
• Ex. Sea otters, prairie dogs
• If it is not there ? will cause populations of
  other species in the ecosystem to go down or
  become extinct
• Can drastically change the ecosystem even though
  it isnt the most abundant species.
• Dominant species most abundant species

Images taken without permission from
http//animal.discovery.com/mammals/prairie-dog/
and http//carinbondar.com/2010/11/this-weeks-cool
-biology-job-sea-otter-population-ecologist/