Science 8-9

mutualism

two organisms benefit

commensalism

one organism benefits, other is not harmed

parasitism

one organism benefits, other is harmed

competition

two species fighting for the same resources

predatory

one organism kills another

population

same species all living in the same area

demography

statistical study of populations

population density

the amount of one species living in a specific area

dispersion

the spacing of organisms in a population relative to another population in that same area

three types of dispersion

clumped, uniform, random

three ways to count a population’s size

direct, sample size, mark and capture

clumped

all in one area

uniform

spaced out orderly

random

no pattern or sense

direct

counting the people in the room

sample size

taking a few people and estimating how many

mark and capture

giving a bird a tag