 Characteristics of Populations  Population Density-The number of individuals per unit of area.  Geographic Distribution- The area inhabited by a population.  Growth Rate- How fast a population of a given species grows or increases in number.

 Factors that influence population growth rate.  Number of births  Number of deaths  Number of individuals that enter or leave the population ▪ Immigration- The movement of individuals into an area. ▪ Emigration- The movement of individuals out of an area.

 Exponential Growth: A growth pattern on which the individuals in a population reproduce at a constant rate.  Under ideal conditions with unlimited resources a population can grow this way  Logistic Growth: A growth pattern in which a population’s growth rate slows or stops following a period of exponential growth.  When a resource becomes less available and begins to slow or stop a population from growing  Carrying Capacity: Largest number of individuals of a population that a given environment can support

 Limiting growth factors are factors that cause population growth to decrease.  1.)Density Dependent Factors: Depend on population size. ▪ Competition ( resources) ▪ Predation (predator vs. prey) ▪ Parasitism/Disease  2.)Density-Independent Factors: Affects all populations regardless of size. Organism population will “crash”. ▪ Climate Extremes (Drought, Flood) ▪ Human Disturbance

 Like the population of other living things the size of the human population tends to increase with time.  Demography- The scientific study of the human population.  Like other population; Births, deaths, etc. affect the human population.  Historical Overview:  Life was different years ago, medicine and technology not as advanced.  Only half of the human population made it to adulthood.  The Industrial Revolution changed that and humans began to grow exponentially.

 Demographic Transition- Change in population from high birth and death rates to low birth and death rates.  Societies modernize: Education, Medicine, Tech.  Demographic transition is complete when birth rate fails to meet death rate, population growth stops.  Hasn’t happen yet in most countries.

 Age structure(diagram)- The numbers of males and females of different ages groups of a population.  Use a diagram to study the age structure of a population.  Future Population Growth????  Populations keep growing  If growth doesn’t slow down serious damage to the global environment is inevitable.