Ecology Communities

Community Vocab. Community = all organisms in area Species richness = # different species determined by - abiotic factors - food supply - evolutionary history - species interactions - physical disturbances (frequency) Highest in Tropics – high primary productivity - old stable ecosystem

Niche = role in ecosystem - all activites & interactions Fundamental niche = niche it would fill if not limited by competition Realized niche = actual role played, area covered, food used etc.

INTERACTIONS Can be…. A) Interspecific – between species B) Intraspecific – within species - competition, mates, social C) Obligatory – needed for survival D) Facultative – helpful but not necessary

Competition Intraspecific & Interspecific 2 types: Interference Competition = one species blocks access of another species to some resource Exploitative Competition = one species is better at using the resource so gets more

Competitive Exclusion Theory 2 species that use identical resources (identical niche)… can not coexist indefinitely One species will go extinct in that area Gause - studied Paramecium sp. - showed competitive exclusion

Resource Partitioning = subdividing resources to allow species to coexist

More types of interactions 1) Predation = (+,-) One predator kills and eats more than one prey organism

2) Parasitoid = (+,-) One parasitoid kills and eats one host organism.

3) Herbivory : (+,-)herbivore eats plant

Symbiotic Relationships Organisms live closley together Names end in –ism Parasitism Mutualism Commensalism

4) Parasitism = (+,-) Many parasites feed on one host organism….try not to kill host

5) Mutualism = (+,+) symbiotic relationship where both benefit

6) Commensalism = (+,0) one organism benefits the other is not affected

More on Predator-Prey Interactions Co-evolution: joint evolution of 2 species that exert selective pressure on each other Lynx & Snowshoe hare also common w/ mutualisms Adaptations: inherited genetic traits that improve an organism’s fitness

Adaptations Can Help plants avoid being eaten Help predators capture prey Help prey avoid predators Match organisms to their habitat

1.Cryptic Coloration Camouflage color Camouflage shape Camouflage behavior

2.Chemical Defense Smell Taste Poison venom

3.Aposematic Coloration Warning color Red/orange Black & some bright color

Arizona Coral Snake

Organism looks/behaves like a different organism 4. Mimicry Organism looks/behaves like a different organism

3 Types of Mimicry 1) A harmless/defenseless mimic looks like a dangerous model Batesian Mimicry

Red next to black venom lack.

2) Two dangerous/bad-tasting organisms mimic each-other Mullerian Mimicry

Monarch Viceroy

3) Harmful predator/parasite mimics harmless model

Cleaner Wrasse Mimic Saber-toothed Blenny * Cleaner Wrasse

5. Physical Defense Armor/Shell/Spines Teeth/Claws Speed/Size