Competition

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Transcript Competition

Competition
Hey!
You!
Get off of my cloud!
Terminology
• Resources
– Something that can be used
– Food, water, mates, a place to grow (for organisms
like plants, mussels, etc.), a hiding place or other
shelter, basking sites
– Renewable or non-renewable
– Limiting resource (in short supply)
• Conditions
– Temperature, pH
– Can’t be used up
Niche
• The functional relationship of an organisms to its
physical and biological environment
• Niches are multidimensional
• Range of physical factors for survival / reproduction
– Temperature, humidity, pH, soil, sunlight, shelter
• Biological factors
– Predators, prey, parasites, competitors (food resources)
• Behavior
– Seasonality, diurnal patterns, movement, social organization
– Ex. - burrowers, nocturnal, migration, social, herd
• If each of these parameters represents a niche, then
whenever two species share the same parameter,
competition for that resource occurs
Competition
• Intraspecific competition
–
–
–
–
Occurs within the species
100% niche overlap here is near 100%
All resource (niche) requirements are the same
Strongest competition
• Interspecific competition
– Competition between species
– Only a few resources are shared
– Ex. – Squirrels and chipmunks
• Food resource is shared, breeding and nesting is not
Competitive Exclusion
• Two species competing for the same limiting
resource in an area cannot coexist
– In general, when two closely related species occupy the same
area, they will eventually compete for a ‘limiting resource’
– One species will be better at the competition and will eventually
displace the other
– Two species cannot occupy the same niche
• There will always be a difference
Forage on the same trees for insects
The nuthatch moves DOWN the trunk when foraging
The creeper moves UP the trunk
Each encounter, see and eat totally different insects
Resource
Partitioning
Limiting competition
Competition and Evolution
• Better competitors get more resources
– Better able to survive
– Better able to reproduce
– Better able to pass on their genetics
• Genetics of the weaker competitors are
lost
Direct
Competitors?
• Green Anole
– Anolis carolinensis
– Native to Fla.
• Brown Anole
– Anolis sagrei
– Introduced (circa 1890)
• Greens dominate natural
settings
• Browns more common in
the human domain
• Is time a factor??
American
Alligator
• Freshwater
• Were
threatened
• Regulated
hunting
• Rebounded
population
American
Crocodile
•
•
•
•
Saltwater
Endangered
Smaller habitat
Greater human
impact