Population Growth and Regulation

population ecology

study of how groups within a species live within an area

community ecology

study of how different species live in an area

ecosystem ecology

study of how all things coexist within an ecosystem

population

group of one species that interacts regularly

population density

size of the population in a given space; affects how often individuals come in contact with each other

population density increases

when individuals are born or immigrate to the area

population density decreases

when individuals die or emigrate out of the region

dispersion

Geographic arrangement of individuals in a population

fecundity

The number of offspring an individual can have in a lifetime

limiting factors

Prevent a population from growing infinitely or even reaching a full potential; deduced by finding what a species needs to survive and determining whether or not it exists in sufficient quantities for continued growth

carrying capacity (K)

The number of individuals are habitat can sustain with its available resources

density dependent factors

factors that inhibit gross because of the environmental stress caused by a population size

ex. Limited food, water, space; competition; predator population expands; damage done by disease

density independent factors

Unaffected by population density or size

ex. natural or man-made disasters, minor weather events, climate change

Exponential growth

population grows at a rate proportional to the size of the population; no limiting factors

ex. invasive/introduced species, recovering from catastrophe, emergent disease

Exponential growth equation

dN/dt = rN

logistic growth

population is limited to the carrying capacity of its habitat

logistic growth equation

dN/dt = rN(K-N)/K

rate of growth (r)

includes exponential model and logistic model; constant proportion of population growth

Malthusian limit

the carrying capacity for human populations, beyond which lies ongoing crises, including famine, disease, and mass death

demographic transition

shift from high birth & death rates to low birth & death rates due to Health care, Sanitation, Education, Social change, Agriculture