Unit 3: Populations

r-selected species

populations with a high intrinsic growth rate often producing many offspring at one time and displaying a J shaped curve

K-selected species

populations with a low intrinsic growth rate, which causes their populations to increase slowly until they reach the carrying capacity of their environment

survivorship curves

distinct patterns of survival over time displayed as 3 types, I, II, III

density dependent factors

influence an individualś probability of survival and reproduction in a manner that depends on the size of the population (disease, competition for food and mates, predation)

density independent factors

have the same effect on an individualś probability of survival and reproduction regardless of population size (floos, hurricanes, tornadoes)

Demography

the branch of sociology that studies the characteristics of human populations

Census

a period count of the population

Population Density

number of individuals per unit area

Population Composition

structure of a population in terms of age, sex and other properties, education

Age-Sex Pyramid

graphic representation of a population showing the percentage of the total population by age and sex

Crude Birth Rate

the number of live births yearly per thousand people in a population

Crude Death Rate

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

Infant Mortality

the death rate during the first year of life

Total Fertility Rate

The number of children born to an average woman in a population during her entire reproductive life

Demographic Transition

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

Doubling Time

the time required for a population to double in size

Exponential Growth

growth pattern in which the individuals in a population reproduce at a constant rate

Linear Growth

Expansion that increases by the same amount during each time interval.

Natural Increase

Crude death rate subtracted from crude birth rate

Population Explosion

the rapid growth of the world's human population during the past century

Nomadism

human movement among a definite set of places

Seasonal Movement

human movements that are taken based on a seasonal basis.

Migration

the movement of organisms between two populations

Emigration

migration from a population

Immigration

Migration into a population

Refugee

an exile who flees for safety

Immigration Law

laws and regulations of a state designed specifically to control immigration into the state

Negative Population Growth

the actual decline in population due to less than replacement births or extensive diseases

Population Momentum

Continued growth of a population due to a high number of individuals at child bearing age.

Doubling Time

The amount of time it takes for a population to double in size. Calculated by TD = 70/r (%)