Biog 2: Species Interactions (11)

Competition

• two organisms benefit from each other's existence
• Ex. Scarlet Honeycreeper with flowers that shape its beak

1 organism benefits, other doesnt receive negatives

Ex. Great White and Ramora

mutually negative interaction where fitness is reduced because of the presence of another organism

between members of same species- going for same resources in an ecosystem

between different species- competition for resources

poisonous baby eucalyptus plant

• "K"
• equilibrium point of birth and death rate

• organisms compete with others attempting to forage, reproduce, or establish in a habitat
• *this is an important mechanism for plants: Ex. Black walnut tree- produce jugalone chemical- natural herbicide

when individuals interfere indirectly by consuming scarce resources (now less available for others)

• ** Competitive Exclusion Principle- complete competitors cannot coexist. They must differ in their use of resources in some way.
• Tested with microbes?

living generally the same, but slightly different- ex: owls eat at night, hawks at day

where predator feeds on prey

wide range of environmental tolerance

• broad range of food choice
• not tied to single location
• may not eat food that is very nutritious
• need lots of territory and food to survive
• Ex. bear- would run out of resources if not euryphagous

narrow range of environmental tolerance

• narrow range of food choice
• choose best food
• get high return on energy investment
• limited competition
• difficulty finding food

ecosystems via top-down trophic relationships

cascading disruptions that pass between trophic lvls

different categories of interrelated organisms in the hierarchy of energy transfer within an ecosystem

species that has a disproportionately large effect on its environment relative to its abundance