31 terms

AP Environmental Science, Chapters 6 and 7

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Population Size
the total number of individuals within a defined area at a given time.
Population Density
the number of individuals per unit area at a given time.
Population Distribution
how individuals are distributed with respect to one another. The three primary forms of _____ ______ are: random, uniform, and clumped.
Population Sex Ratio
the ratio of males to females in a given population. This is helpful to scientists in that, as the number of females in a population largely dictates future population growth, it helps with estimations of population growth/decreases.
Population Age Structure
the grouping and organization of individuals according to varying ages. This helps scientists predict how fast a population will grow.
Density-dependent Factors
these represent circumstances in which the size of the population will influence an individual's probability of survival. (ex. food)
Density-independent factors
these represent circumstances in which the size of the population has no effect on an individual's probability of survival. (ex. natural disasters, freezes that prevent and individual/group of individuals from attaining a resource necessary for survival)
Growth Rate
the number of offspring an individual can produce in a given time period, minus the deaths of the individual or offspring during the same period
Intrinsic Growth Rate
this is the maximum potential for growth met under ideal conditions with unlimited resources
J-shaped Curve
the graph of an exponential model
Logistic Growth
this occurs when a population's growth is initially exponential, but slows as the population approaches the carrying capacity.
S-shaped Curve
the graph of a logistic model
K-selected Species
the population of a species that grows slowly until it reaches carrying capacity. (ex. whales, elephants, and humans)
R-selected Species
the population of a species that grows quickly often resulting by overshoots and die-offs.(ex. mosquitos, dandelions, etc.) Such die-offs are often occasioned by food availability declines prior to the birth of offspring, resulting in massive overpopulation relative to the amount of food.
Demography
the study of human populations and population trends, including: changes in population size, fertility, life expectancy, age structure, migration, etc.
Immigration
the movement of people into a country
Emigration
the movement of people out of a country
Net migration rate
the difference between immigration and emigration in a given year per 1,000 people in a country
Crude Birth Rate
(CBR), the number of births per 1,000 individuals per year
Crude Death Rate
(CDR) the number of deaths per 1,000 individuals per year
Global Population Growth Rate
(CBR-CDR)/10
National Population Growth Rate
((CBR + immigration) - (CDR + emigration)) / 10
Doubling Time
[in years], 70/growth rate
Total Fertility Rate
an estimate of the average number of children that each woman in a population will bear
Replacement Level Fertility
the total fertility rate required to offset the average number of deaths in a population and for the current population size to remain stable
Developed Countries
countries with relatively high levels of industrialization and income
Developing Countries
countries with relatively low levels of industrialization, and income of less than $3 per person per day.
Community
incorporates all of the populations within a given area. Many ________s are named based on the dominant population(s) of flora or fauna present in them.
Population Ecology
the study of factors that cause populations to increase or decrease
Limiting Resource
a resource that a population cannot live without and which occurs in quantities lower than the population would require to increase in size.
Carrying Capacity
denoted as "K," this is the limit to a population size that can sustain itself.