 6.7 Billion

 Geographic distribution  Density  Growth Rate

 Geographic distribution- area that is inhabited  Density  Growth Rate

 Geographic distribution  Density- number of individuals per unit area  Growth Rate

 Geographic distribution  Density- number of individuals per unit area  Growth Rate

 Geographic distribution  Density  Growth Rate- how fast the population grows

Population size is determined by  Number of births  Number of deaths  Number of individuals that enter or leave the population

 Birth rate- how many are born  Baby Boom  Death rate- how many die  Black Plague

Birth RateDeath RateOverall Rate

 Immigration- movement into area  Emigration- movement out of area  What causes people to immigrate or emigrate?  What causes bears to immigrate or emigrate?

 Where are the high birth rates in the world?  Where are the high death rates in the world?  Many developed nations have a negative growth rate. Why?

-ability to reproduce quickly -nutrients -space -water

Bacteria- divide every 20 minutes one day- 4,720,000,000,000,000,000,000 What is the reproduction rate for a mouse? What is the reproduction rate for a human?

When a population reproduces at a constant rate. This occurs only under ideal conditions with unlimited resources.

Logistic growth- occurs when a population’s growth slows or stops after exponential growth Why does a population stop growing exponentially?  Birth rate decreases  Death rate increases  Immigration decreases  Emigration increases

Carrying capacity- The largest number of individuals that an environment can support

Limiting factor- a factor that causes population growth to decrease Competition Predation Parasitism and disease Human disturbances Drought and other climate extremes

 Density-dependent limiting factor- depends on the population size  Competition- food, water, space, sunlight  Same species  Different species  Competitive exclusion principle  No two species can occupy the same niche in the same habitat at the same time

 Predation predator-prey relationship Parasitism and Disease

Density-Independent Factors- affect all populations, regardless of size Unusual weather Natural disasters Seasonal cycles Human activities- damming rivers and clear- cutting forests

Demography- the scientific study of human populations Demographic transition- a dramatic change in birth and death rates

 1. Birth rates stay same, Death rates decline  2. Birth rates decline, death rates stay low Birth RateDeath RateOverall Rate

 Age-Structure Diagram- graph of the numbers of people in different age groups

 How many people can the world support?  What are the things that people need to live?  -food  -water  -housing  -jobs

Resourcesvs.Population