Unit 3 Flashcards
IPAT equation
A conceptual representation of the three major factors that influence environmental Impact: Population of humans, Affluence, Technology.
Density-independent factor
A factor that has the same effect on an individual’s probability of survival and the amount of reproduction at any population size.
Density-dependent factor
A factor that influences an individual’s probability of survival and reproduction in a manner that depends on the size of the population.
Survivorship curve
A graph that represents the distinct patterns of species survival as a function of age.
Logistic growth model
A growth model that describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment.
Exponential growth model
A growth model that estimates a population’s future size after a period of time based on the biotic potential and the number of reproducing individuals currently in the population.
Rule of 70
A method which dictates that by dividing the number 70 by the percentage population growth rate we can determine a population’s doubling time.
Type II survivorship curve
A pattern of survival over time in which there is a relatively constant decline in survivorship throughout most of the life span.
Type I survivorship curve
A pattern of survival over time in which there is high survival throughout most of the life span, but then individuals start to die in large numbers as they approach old age.
Type III survivorship curve
A pattern of survival over time in which there is low survivorship (a high death rate) early in life with few individuals reaching adulthood.
Dieback (Die-off)
A rapid decline in a population due to death.
Limiting resource
A resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size.
Demographer
A scientist in the field of demography.
r-selected species
A species that has a high intrinsic growth rate, and their population typically increases rapidly.
K-selected species
A species with a low intrinsic growth rate that causes the population to increase slowly until it reaches the carrying capacity of the environment.
Theory of demographic transition
A theory that states that a country moves from high to lower birth and death rates as development occurs and that country moves from a preindustrial to an industrialized economic system.
Age structure diagram
A visual representation of the number of individuals within specific age groups for a country, typically expressed for males and females.
Population pyramid
An age structure diagram that is widest at the bottom and smallest at the top, typical of developing countries.
Total fertility rate (TFR)
An estimate of the average number of children that each woman in a population will bear throughout her childbearing years.
Population momentum
Continued population growth after growth reduction measures have been implemented.
Developed countries
Countries that have relatively high levels of industrialization and income.
Developing countries
Countries that have relatively low levels of industrialization and income.
Population growth models
Mathematical equations that can be used to predict population size at any moment in time.
Fecundity
The ability to produce an abundance of offspring.
