group of individuals of ONE SPECIES that live in A PARTICULAR AREA
What determines a population's growth?
The characteristics of the population and the environment they live in determine a population's growth
number of individuals in different age classes
-pre reproductive age: 0-15
-reproductive age: 15-45
-post-reproductive age: 46+
age structure diagram
Determines how fast the population will grow
(crude birth rate + immigration rate) - (crude death rate + emigration rate)
rates are expressed as individuals per 1000
to express as a percentage: growth rate x 100%
Example: 20/1000 x 100% = 2%
A STABLE RATE OF GROWTH leads to Exponential Growth
As the population size increases, the same percentage increase becomes a larger total increase
J-Curve in Population
Occurs when a population is small and environmental conditions are ideal
Physical, chemical, and biological factors that limit the amount of growth that is possible. Ex: space, nutrients, predators
All limiting factors together make up the "environmental resistance"
made up by all limiting factors
determines Carrying Capacity
the maximum population size that an environment can sustain
Determines how big the population can become
determined by Environmental Resistance
Carrying Capacity can change when limiting factors change
Increasing our Carrying Capacity
Technology has allowed us to raise Earth's carrying capacity for our species time and again
Tool-making, agriculture, and industrialization each enabled humans to sustain greater populations
Total Fertility Rate
The average number of children born per female during her lifetime
The average number of years that a person can expect to live from birth
Human Population Growth
Human population growth has been greater than exponential.
Growth rate has increased over time (mostly because of lower death rates)
Varies from place to place
Where is the majority of new population growth occurring?
The majority of new population growth is occurring in DEVELOPING COUNTRIES
The Demographic Transition
a model of economic and cultural change to explain declining death rates, declining birth rates, and rising life expectancies in Western Nations as they became industrialized
Doing a Demographic Transition, what growth rates to become very high?
Growth rates can become very high because death rate declines before birth rate
Because most developed nations have passed through the demographic transition, what has happened to the global growth rate?
Because most developed nations have passed through the demographic transition, the GROWTH RATE has DECREASED
High death rates and high birth rates
death rates fall due to rising food production and better medical care.
birth rates remain high causing population to surge
birth rates fall - women are employed and as children become less economically useful in an urban setting
population growth rate declines
birth and death rates remain low and stable
society enjoys fruits of industrialization without threat of runaway population growth
Since the 1960's, what has happened to the annual growth rate of the world population?
The annual growth rate of the world population has DECLINED since the 1960s
(population size is still rising)
Total Fertility Rate (TFR)
average number of children born per woman during her lifetime
the TFR that keeps population size stable
for humans RF = 2.1
Africans have highest, Europe has lowest
Female literacy and school enrollment are correlated with TFR, more educated have fewer children
Family planning, health care, and reproductive education can lower TFRs
Is poverty correlated with population growth?
YES, poverty is correlated with population growth.
I = P x A x T x S
(P)opulation - individuals need space and resources
(A)ffluence - greater per capita resource use
(T)echnology - increased exploitation of resources
(S)ensitivity - how sensitive an area is to human pressure
Also: effects of education, laws, and ethics on the formula
humans have surpassed the Earth's capacity to support us
we are using renewable resources 30% faster than they are being replenished
Modeling population and it's consequences
some models show population growth leading to resource depletion, which can result in declining food production, industrial output, and population
What is environmental impact dependent on?
Environmental impact is dependent on POPULATION SIZE as well as AFFLUENCE (abundance of wealth) and TECHNOLOGY