3.1 - 3.9 AP ES 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.

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 sustain

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.

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.

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.

population density

Number of individuals per unit area

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

The equation used to calculate the doubling time for a population. 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.

Population momentum

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

Demographic Transition Model

Refers to the transition from high to lower birth and death rates in a country or region as development occurs and that country moves from a preindustrial to an industrialized economic system

Developed countries

countries with strong economies and a higher quality of life

Developing countries

countries with less productive economies and a lower quality of life

post-industrial stage (Stage 4/5 Low Stationary)

(demographic transition) low birth & death rates

pre-industrial stage (Stage 1 High Stationary)

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

Industrial stage (Stage 3 Late Expanding)

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

Transitional stage (Stage 2 Early Expanding)

(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