Community Ecology Big Idea 4: Biological Systems Interact

ECOLOGY Study of living organisms and their interactions with the non/ living environment

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., H 2 O, 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).

What’s My Niche?

Communities Have Competition… Interspecific Competition: occurs b/t diff. species. Due to resources in short supply.

Intraspecific Competition

Intra or Interspecific Competition?

Competitive Exclusion 2 species cannot coexist in a community if their niches are identical. (Gause’s Law) Paramecium caudatumParamecium aurelia Gause’s Experiment

Logistic Growth

When Niches are the Same… Species can evolve to coexist Resource partitioning- a species changes behavior so it can coexist w/ a similar species.

Resource Partitioning

Keystone Species Key members of community –Critical elements –NOT always most abundant – ALWAYS most important KEY to conservation efforts

Predation in Communities Members of a predator species prey on members of a prey species

Stalking, Keen eyes, Venom Natural Weapons: Fangs, claws Flexible bodies and Larger Size Predator Strategies

Prey Strategies Defense Techniques: Inflate, Flee, Fight Back, Stab, Poison

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

Herbivor y Herbivore only eats a part of plant/alga. Plants may have chemicals to deter

Symbioses in Communities Symbiosis: relationship b/t 2 species Mutualism (+,+) Commensalism (+,0) Parasitism (+,-)

Mutualism Both Species Benefit Rhinos and oxpeckers

Mycorrhizae Symbiotic fungus found on plant roots Aids in water retention, mineral uptake (nitrates) W/out MWith M

Commensalism One member is helped, the other neither benefits or is harmed Cows and Cattle Egrets

Parasiti sm + and - relationship parasite benefits, host loses parasite usually smaller than host Leech Bite, Thailand Lamprey