8.2 - interactions between living things

tropic level

position in a food chain

primary producers

autotrophs - use sunlight to make food

consumers

primary - herbivores

secondary - eat herbivores

tertiary - eat secondary

apex predators - top of chain

ten-percent law

10% of energy transferred to next level, 90% used or lost as heat d

decomposers

(fungi, bacteria) recycle nutrients

food webs

show complex feeding relationships beyond linear food chains

populations

growth phases

lag phase (pop)

slow start as organisms adapt

exponential phase (pop)

rapid growth

stationary phase

growth slows as resources run low

death phase (pop)

decline due to depleted resources/waste

carrying capacity

maximum pop an enviornment can support

type 1 (survivorship)

few offspring, high parental care

ex. humans

type 2 (surviviorship)

constant death rate

ex. birds

type 3 (surviviorship)

many offspring, low survival

ex. insects

r-selected species (selection theory)

high repro, short lifespan

K-selected species (selection theory)

low repro, long lifespan

keystone species

organisms with a disproportionate effect on their ecosystem

ex. purple sea star - apex pred in intertidal zones