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4.1 Studying Ecology 4.2 Describing Populations 4.3 Population Growth

biosphere

part of Earth in which life exists including land, water, and air or atmosphere

ecosystem

a collection of all the organisms that live in a particular place, together with their nonliving, or physical, environment

organism

a living thing that has (or can develop) the ability to act or function independently

species

group of similar organisms that can breed and produce fertile offspring

population

group of individuals of the same species that live in the same area

community

(ecology) a group of interdependent organisms inhabiting the same region and interacting with each other

habitat

the place or set of environmental conditions in which a particular organism lives

biotic factor

any living part of an environment

abiotic factor

a nonliving part of an ecosystem

limiting factor

an environmental factor that prevents a population from increasing

carrying capacity

the maximum population size that can be supported by the available resources

niche

organism's role, or job, in its habitat

population dynamics

the study of changes in birth rate, death rate, and migration that affect the total number of organisms in a given ecosystem

environment

the circumstances or conditions that surround an organism or group of organisms as well as the complex of social or cultural conditions that affect an individual or community

ecology

the study of how organisms interact with each other and with their environments

resource

anything an organism needs, including nutrients, shelter, breeding sites, and mates

population size

describes the number of individual organism present in a given population at a given time

population density

describes the number of individuals within a population per unit area

population distribution

describes how organisms are arranged within an area

age structure

describes the relative numbers of organism of each age within a population

sex ratio

a populations proportion of males to females

survivorship curve

graph that shows the likelihood of death at various ages

immigration

arrival of individuals from outside a given area

emigration

departure of individuals from a given area

migration

seasonal movement into and out of an area

exponential growth

population increases by a fixed percentage each year

logistic growth

describes how a populations initial exponential increase is slowed and finally stopped by limiting factors

density-dependent factor

limiting factors whose influence changes with population density

density-independent factor

limiting factors whose influence is not affected by population density

biotic potential

maximum ability to produce offspring in ideal conditions

natality

birth rate

mortality

death rate

gestation time

the period of development of a mammal, from fertilization until birth

generation time

average time between one generation of offspring and the next

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