Ch5 - Populations Flashcards
How would you describe populations?
- Geographic Range: area that a population takes up
- Density & Distribution: # per unit area & how they are spaced out
- Growth rate: Exponential/Logistic Growth – deathrate vs birthrate
- Agre structure:# of males/females of diff ages
What affects population growth?
birthrate, deathrate, immigration, emigration
Immigration vs Emigration
Immigration: if individuals move into a range from somewhere else – a population grows
Emigration: when individuals move out of a population’s range – a population decreases
What is carrying capacity?
Max number of individuals of a particular species that an ecosystem can support
What is exponential growth?
rapid growth due to unlimited resources & absence of predation/disease
What is logistic growth?
Occurs when population’s growth slows then stops after exponential growth
Birth Rate decrease, death rate increase, immigration rate decrease, emigration rate increase
What are limiting factors? 2 types?
Limiting Factors: factor that controls the growth of a population
Density Dependent (biological factor)
Competition: As population grows, organisms fight for resources
Predator-prey relationship
Prey increase – predator increase
Prey decrease – predator decrease
Parasitism & disease: organisms feed while killing their hosts
Stress from overcrowding
Density Independent: affect population regardless of population size & density
Behavior/Preferences
Biotic
Invasive Species
Drought/Weather
What is demography?
the statistical study of human populations
What is a demographic transition? Example
tendency of a population to shift from high birth & death rates to low birth & death rates (population grows slowly)
Ex. While improving medicine & sanitation decreases death rates, people then choose to limit the size of their families - decreasing birth rates
