community ecology big idea 4: biological systems interact
TRANSCRIPT
Who Lives Where?
• Orgs adapted to a specific set environmental conditions, through evolution (natural selection)
Peppered Moths of England
• Dispersal: Movement of species from areas of high pop. density to low.
• Can be caused by:1. Species expanded
range naturally 2. Species was
transplanted Great tailed grackle: Moved north to Gulf of Mexico
Who Lives Where?
• Abiotic and Biotic Factors are Limiting!!
• Abiotic: temp., H2O, sun, wind, soil, climate.
• Biotic: animals, plants, bacteria
Ex: Tidepools in Intertidal Zones, Must withstand exposure to sun at
low tide.
Who Lives Where?
Biological Communities
• An area where different pops interact w/ each other w/ no boundaries
• Leads to creation of ecological niches- a role in an ecosystem (fills a niche).
Communities Have Competition…
• Interspecific Competition: occurs b/t diff. species.
• Due to resources in short supply.
Competitive Exclusion
• 2 species cannot coexist in a community if their niches are identical. (Gause’s Law)
Paramecium caudatum Paramecium aurelia
Gause’s Experiment
When Niches are the Same…• Species can
evolve to coexist
• Resource partitioning- a
species changes
behavior so it can coexist w/ a similar species.
Keystone Species
• Key members of community– Critical elements
– NOT always most abundant– ALWAYS most important
• KEY to conservation efforts
• Stalking, Keen eyes, Venom• Natural Weapons: Fangs, claws • Flexible bodies and Larger Size
Predator Strategies
Mimicry• Batesian mimicry: a
harmless species looks like a harmful species
• Mullerian mimicry: 2 harmful species look like each other
Scarlet King Snake
Coral Snake
Cuckoo Bee
Yellow jacket
Predation Feedback Systems• Positive feedback (outcome is +) for predator
• gets to eat prey, can reproduce…• Negative feedback (outcome is -) =
• prey population falls, no food, decrease in predator population
Symbioses in Communities
Symbiosis: relationship b/t
2 species
•Mutualism (+,+)
•Commensalism (+,0)
•Parasitism (+,-)
Mycorrhizae
• Symbiotic fungus found on plant roots
• Aids in water retention, mineral uptake (nitrates)
W/out M With M
Commensalism
• One member is helped, the other neither benefits or is harmed
• Cows and Cattle Egrets