Population Ecology

dispersion

pattern of spacing between individuals

determining population size and density

1. count every individual

2. random sampling

3. mark - recapture method

clumped dispersal

most common; near required resources

uniform dispersal

usually antagonistic interactions

random dispersal

unpredictable spacing; not common in nature

demography

study of vital statistics of populations and how they change over time

carrying capacity

maximum stable population which can be sustained by environment

life history

traits that affect an organism’s schedule of reproduction, survival, and growth.

the three variables of life history

1. age of sexual maturation

2. how often organism reproduce

3. number of off-springs produced per reproductive episode

semelparity

many off-springs produced at once; individual often dies afterwards; less stable environment

iteroparity

repeated reproduction; few, but large off-spring; more stable environment

critical factor

survival rate of off-spring and repeated reproduction when resources are limitedk

k - selection

population is close to carrying capacity; ex. humans

r - selection

maximize reproductive success ex. cockroaches

density - dependent limitations of population growth

population matters; ex. predation, disease, competition

density - independent limitations of population growth

population is not a factor; ex. natural disasters

population dynamics

population fluctuation due to biotic & abiotic factors

boom and bust cycles

predator - prey interactions