AP Unit 8: Ecology

organisms send signals to each other in response to…

changes in their environment

endotherms

use thermal energy generated from their metabolism to maintain their body temp

ectotherms

obtain heat from their environment

metabolic rate

total amount of energy an organism uses per unit time

as size of organism INC

metabolic rate DEC

a net gain in energy can result in _____ _____

energy storage

a net loss of energy can result in the…

loss of mass or even the death of the organism

trophic levels

represent steps in food and energy transfers between organisms in an ecosystem

primary productivity

rate at which autotrophs use energy to convert inorganic matter into organic matter

decomposers

break down dead organic material, allowing the nutrients in dead organisms to be recycled through organisms

detritivores

organisms that obtain energy by consuming the organic waste of dead plants + animals

10% rule

only 10% of energy is transferred from one trophic level to the next

bottom-up regulation

population of producers DEC (not sufficient food for higher trophic levels)

top-down

top predators are removed (population sizes of other trophic levels may exceed producers’ ability to produce enough food to support them)

Birth Rate is MORE than Death Rate, population INC or DEC

INC

Birth Rate is LESS than Death Rate, population INC or DEC

DEC

the larger the population, the (faster/slower) the growth rate

faster

factors that limit growth

density-dependent and density-independent

density-dependent factors

disease, predation, competition for food, habitat, mates

density-independent factors

natural disaster, temp, predation

carrying capacity

maximum population that can be supported by available resources in an environment

density-dependent and independent result in _____ growth

logistic

exponential growth is what letter shape-curve

J-curve

logistical growth is what letter shape-curve

S-curve

K-selected population

• stable environment

• stable population size near carrying capacity

• more energy available

• reproduce more than once per lifetime, few offspring per reproductive rate

• greater levels of parental care in their offspring - higher survival rates

• logistical growth

• sensitive to density-dependent factors

r-selected reproductive strategies

• unstable environments

• less energy available

• large numbers of offspring

• no parental care for offspring, leading to lower survival rates in offspring

• boom and bust cycles: population exceeds carrying capacity (“booms”) followed by rapid decreases in population size (“busts”)

• exponential growth

niche partitioning

competing species may coexist if they use resources available in their habitat differently

trophic cascade

far-reaching effects of the reduction of one trophic level in a food web

parasitism

one species benefits while host gets harmed

commensalism

one species benefits while other neither benefited nor harmed

mutualism

both species benefit

Keystone species

disproportionately large effect on its ecosystem relative to its abundance