community ecology relationships between organisms ap biology
TRANSCRIPT
Community EcologyCommunity Ecology
Relationships Between OrganismsRelationships Between Organisms
AP Biology
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
Competition
• Competition = when two species compete for the same resource
• Competition can lead to competitive exclusion or resource partitioning
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)
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
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
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)
Animal Defenses: Aposematic coloring
Coloring or markings to warn off predators
Animal Defenses : Cryptic coloration
Coloring that disguises an animal’s shape
Animal Defenses: Batesian MimicryA species mimics a successful species but lacks the actual attribute– “pretending to be harmful”
Scarlet king snake
harmful
Not harmful
Müllerian Mimicry
Monarch butterfly
Viceroy butterfly
A species resembles another successful (harmful) species and shares the attribute (is also harmful)
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/1998-02/Glandular_hair_leaf_72dpi.JPG and http://fm2.fieldmuseum.org/plantguides/jpgs/LOGA-stry-toxi-pan-2735.jpg
Summary of Species-Species Interactions
Competition -/-
Predation +/-
Herbivory +/-
Parasitism +/-
Disease (Pathogen) +/-
Mutualism +/+
Commensalism +/0
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 isn’t 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/