1. Community Interactions

2. Community Interactions
Community: Many different species interacting in the same environment.
Three types of interactions:
Competition
Predation
Symbiosis

3. Competition Defined: Competing for resources
Water, nutrients, light, food, space
Occurs due to a limited number of resources
Intraspecific competition: When organisms of the same species compete for resources.
Interspecific competition: When organisms of differing species compete for resources.
Competitive exclusion principle: No two species can occupy the same niche in the same habitat at the same time.
Example: What happens to the neighborhood coffee shop when a Starbucks is built next to it?

4. Predation
Defined: when an organism captures and feeds on another organism.
Predator = hunter
Prey = hunted

5. Symbiosis
Defined: a relationship between two or more species that live in direct contact with one another.
Three types
Mutualism
Commensalism
Parasitism

6. Mutualism Defined: both species benefit from a relationship.
Fungus obtains nutrients from the algae
Fish receives protection and a home
Anemone feeds on undigested food from the fish
Algae lives amongst the fungal cells
Bird receives food
Crocodile has parasites removed
Defined: both species benefit from a relationship.
Ex: Lichens (fungus and Algae)
Ex: Clown fish and anemones
Ex: Cleaner birds and crocodiles

7. Commensalism
Defined: One member of a symbiotic relationship benefits and the other is neither helped nor harmed
Ex: Cattle and Birds
Birds eat insects stirred up by the cattle
Ex: Barnacles and whales
Barnacles grow on whale

8. + Ø Human Our eyelashes are home to tiny mites
that feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle.
Demodicids Eyelash mites find all they need to survive in the tiny follicles
of eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope. +
Organism benefits Ø
Organism is not affected
Commensalism

9. Parasitism
Defined: One creature benefits and one creature (the host) is harmed
Endoparasitism:
A parasite that inhabits the inside of an organism.
Ex: Tapeworm feeds within a human’s intestines absorbing his/her nutrients
Ectoparasitism:
A parasite that inhabits the outside of an organism.
Ex: A leech feeds on the blood of an organism from a host’s skin.

10. Identify these relationships

11. Review What is a community?
Name the 3 types if community interactions.
When do organisms usually compete?
How do predators and prey interact?
Name the 3 types of symbiosis.
What is the competitive exclusion principle?
How does mutualism, commensalism, and parasitism differ?
How is predation and parasitism differ?