20.1: Species Interactions, cont.

Competition and predation are two Competition and predation are two important ways in which organisms interact.  

1. Competition- occurs when two organisms fight for the same limited resources.  

A. Intraspecific competition - competition between organisms of same species   Example: Zebras fighting for mates

B. Interspecific competition- competition between different species   Example: Different types of barnacles compete for rock space

i. Competitive exclusion- when two species are competing for same resources one species will be better suited to the niche other species will be pushed into another niche (niche partitioning) or become extinct    

  c. ) niche partitioning- dividing of niche by two competing species (e.g. top or tree, or bottom of tree)

2. Predation- process by which one organism captures and feeds upon another organism. 

3. Symbiosis- close ecological relationship between two or more organisms of different species that live in direct contact  

MUTUALISM Mutualism: ( +/+) both benefit EX. Clown fish get shelter and anemone gets free cleaning.

B. COMMENSALISM Commensalism: (+/0) one benefits and one neutral EX. Barnacles on Grey Whale

C. PARASITISM Parasitism: +/- (but not killed) EX. intestinal worms / humans 1. parasite: small and lives on or in the host organism 2. weaken the host 3. evolutionary adaptation kept the host healthy enough to allow parasite reproduction