APES Unit 3: Populations

K-selected species

Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age.

r-selected species

Species that reproduce early in their life span and produce large numbers of usually small and short-lived offspring in a short period, low paternal care

Competition

the struggle between organisms to survive in a habitat with limited resources

Biotic potential

Maximum rate at which the population of a given species can increase when there are no limits on its rate of growth.

Invasive species

plants and animals that have migrated to places where they are not native

Survivorship curves

a graph that represents the distinct patterns of species survival as a function of age

Type I survivorship curve

A survivorship curve in which newborns, juveniles, and young adults all have high survival rates and death rates do not begin to increase greatly until old age.

Type II survivorship curve

Experience roughly a constant mortality rate regardless of age. Prey animals such as birds can follow this pattern of survival.

Type III survivorship

Experience the greatest mortality early on in life, with relatively low rates of death for those surviving. Usually r-selected.

J-shaped curve (exponential growth)

Growth where there is unlimited resources and no competition

S-shaped curve (logistic growth)

Where the community has reached its carrying capacity

Carrying capacity (K)

Maximum population size that a particular environment can support.

Ecosystem

A biological community of interacting organisms and their physical environment.

Overshoot

when a population becomes larger than the environment's carrying capacity

Dieback

Sharp reduction in the population of a species when its numbers exceed the carrying capacity of its habitat.

Depletion

reduction in the number or quantity of something

Famine

an extreme shortage of food

Population growth

An increase in population over a period of time.

Finite

limited

Fecundity

fertility

Desalinization

A process of removing salt from ocean water

Pandemic

an epidemic that is geographically widespread

Epidemic

A widespread outbreak of an infectious disease.

Age structure diagrams

broad base = rapid growth; narrow base = negative growth; uniform shape = zero growth

Population growth rates

-A country's is determined by its natural increase expressed as a percentage

-For example, a country's natural increase with a CBR of 22 and a CDR of 12 is 10 per 1,000, which translates to a rate of 1 percent

Total fertility rate (TFR)

The average number of children born to a woman during her childbearing years.

Fertility

the incidence of childbearing in a country's population

replacement fertility rate

the total fertility rate needed for a population to replace itself = 2.1

Mortality

death rate

Life expectancy

A figure indicating how long, on average, a person may be expected to live

Per capita

per person

Infant mortality rates

The percentage of children who die before their first birthday within a particular area or country.

Death rates

population density

Number of individuals per unit area

Malthusian theory

focuses on how the exponential growth of a population can outpace growth of the food supply and lead to social degradation and disorder

Density-independent factors

limiting factor that affects all populations in similar ways, regardless of population size eg. flood, fire, other natural disasters

Density-dependent factors

factor that limits a population more as population density increases eg. food, shelters, water, spread of disease

Rule of 70

Doubling time (in years) = 70/(percentage growth rate).

Doubling time

The number of years needed to double a population

Crude birth rate

The total number of live births in a year for every 1,000 people

Crude death rate

The number of deaths per year per 1,000 people.

Overpopulation

The number of people in an area exceeds the capacity of the environment to support life at a decent standard of living.

Standard of living

Quality of life based on ownership of necessities and luxuries that make life easier.

Import vs. Export

Goods that are purchased are imported (into a country). Goods that are exported are sold for profit (sent out of the country).

Gross domestic product (GDP)

A measurement of the total goods and services produced within a country.

Population momentum

continued population growth that does not slow in response to growth reduction measures

Demographic transition

change in a population from high birth and death rates to low birth and death rates

4-stage demographic transition model (DTM)

Infant mortality rates

Developed countries

countries with strong economies and a high quality of life

Developing countries

countries with less productive economies and a lower quality of life

Demography

The scientific study of population characteristics.

post-industrial stage

(demographic transition) low birth & death rates

pre-industrial stage

birth and death rates high, population grows slowly, infant mortality high

Industrial stage

(demographic transition) decline in birth rate, population growth slows

Transitional stage

(demographic transition) death rate lower, better health care, population grows fast

Birth control

Any method used to reduce births, including celibacy, delayed marriage, contraception; devices or medication that prevent implantation of fertilized zygotes, and induced abortions

Immigration

Movement of individuals into a population

Emigration

movement of individuals out of a population