Population Flashcards
population
a group of the same species that occupy the same place at the same time
Population growth rate
how fast a given population grows
Calculate growth rate
Birth rate - death rate
Natality
birthrate in a given time
Mortality
death rate in a given time
immigration
organisms moving into a population
emigration
organisms moving away from a population
Immigration and emigration are usually about ______ in a population
equal
What are the 2 growth models
Exponiental growth
Logistical growth
Organisms moving into or out of a population also effects the of …..
individuals in the population
exponential growth model
occurs under ideal circumstances and that all populations grow exponentially until some limiting factor slows the population growth
examples of ideal circumstances
unlimited resources, no predators/ disease
Logistic growth model
the curve on the exponential growth model where the population growth slows typically due to some environmental pressure
Exponential growth occurs until..
the population reaches its carrying capacity
unrestricted growth
exponiental
restricted growth
logistic
carrying capacity
maximum number of individuals in a species that and environment can support for the long term
carrying capacity is limited by
the energy, oxygen, water, and nutrients available
Population density
the number of organisms per unit area
population limiting factors definition
anything that keeps a population from growing forever
populations reach their carrying capacity due to
limiting factors
2 types of population limiting factors
density-dependent
density- independent
density independent factors
any factor in the environment that does not depend on the number of members in a population per unit area
density independent factors
examples
Weather events
fire
human alterations of the environment
air, land, and water pollution
density dependant factors
any factor in the environment that depends on the number of members in a population per unit area
density dependant factors examples
Biotic factors
disease
competition
parasites
