Group of organisms of the same species occupying a given space at a particular time.
Local populations of interbreeding organisms.
Primary: Population Parameters: Density
: Immigration & Natality
: Mortality & Emigration
Secondary Characterisics of a population
genetic composition and variability
Exponential population Growth Occurs when?
A population has unlimited resources
Logistic Population Growth
Stabilizing Factors which maintain a population at an equilibrium level
Density -independent population growth
Act upon individuals without regard to population density:
Drought, Severe winter, hurricane & fire
Population size exceeds the carrying capacity. ( bacteria & Humans)
Annual rate of natural population Change
(Birth rate - Death rate) / 1,000 persons
Carrying Capacity for Humans
50 billion people
-if the entire ecological capacity of earth was devoted to the maintenance of human populations
-We would have extremely dense human populations.
World population growth trends
Increased proportion living in urban areas. (future 48-60% expected)
-Fast in LDC's
-Slow in MDC's
Increase in the number of megacities (pop> 1million)
Poverty moving from rural to urban problem.
Population Growth Projections
Increase to 8 billion in 20 years
With a majority born in low and middle income nations.