Unit 3 Populations 🤼 Flashcards
Population
a group of organisms of the same species that inhabit a defined geographic area at the same time
Dispersion
how individuals of a population are spaces within a region
Age structure
pyramids that are used to predict population trends
Range of Tolerance
requirements for successful growth, development and reproduction
Limiting Factors
anything that constrains a population’s size and slows or stops it from growing
Population Density
number of individuals of a population that inhabit a certain area
ex) number of squirrels in a forest
Density-dependent factors
limiting factors that are purely a result of the size of the population
ex) predation, competition for food and living space, disease
Density independent Factors
limiting factors that operate independently of population size
ex) fires, storms, earthquakes
Exponential Growth
J-curve unrestricted growth
Logistic Growth
s-curve model for what exists in natural settings
Biotic potential
how much a pop would grow if there were unlimited resources
Environmental resistance
conditions that slow a populations growth
Carrying capacity
maximum population size that can be supported by the available resources in a region
r-selected species
reproduce early in life
high capacity for reproduction
little or no care is given to the offspring
k-seleteced species
reproduce later in life
produce fewer offspring
devote time to raising offspring
survivorship curve
Type I- (k-selected) majority of offspring lives for a long time, but will eventually die off
Type II- offspring has a 50-50 chance of surviving to old age
Type III- (r-selected) most offspring die young, but if they live to a certain age, they will live a long life
Cultural Carrying capacity
the ability of a human population to thrive and create a culture in meager circumstances
crude birth rate
indicates the number of births occurring during the year, per 1,000 population estimated at midyear
Crude death rate
indicates the number of deaths occurring during the year, per 1,000 population estimated at midyear
Population change (equation)
((birth rate+immigration)-(death rate+emigration))/1,000
Replacement-level fertility
number of children a couple must have in order to replace themselves in a population
Total Fertility rate (TFR)
number of children a woman in a given population will bear in her life
based on analysis of data from previous years
assume conditions of the past and the future
Doubling time (equation)
70% / growth rate of a population
Migration
the seasonal movement of animals from one habitat to another in search of food, better conditions, or reproductive needs
Immigration
movement of people into a population
Emigration
movement of people out of a population
Demographic transition
the trend of declining birth and death rates, resulting in a substantive change in the age distribution of a population
Stage 1: Pre-industrial
slow growth rate, high birth and death rates
harsh living conditions
Stage 2: Transitional
high birthrate b/c of culture and lack of women’s education, but the death rate is lower due to better food, water, and healthcare
rapid population growth
Stage 3: Industrial
population growth Is fairly high, but the birth rate drops closer to the death rate
Stage 4: Postindustrial
population approaches and reaches or goes below zero growth rate
ecological footprint
environmental impact of a population
