Chapter 6 - Populations

Studies the dynamics of species’ populations and how these populations interact with the environment.
Biotic Potential
* Maximum reproductive capacity of an organism under optimum environmental conditions.
* Often expressed as a percentage.
Carrying Capacity
* Refers to the number of individuals that can be supported in a given area sustainably.
J-Curve
* In a new environment, the population density of an organism increases rapidly in an exponential or logarithmic form, but then stops abruptly as environmental resistance or some other factor becomes effective.
S-Curve
* Occurs when in a new environment, the population density of an organism increases slowly at first, then increases rapidly, reaching an exponential growth rate like the J-Curve, but then slows down to zero when the population stabilizes.
Reproductive Strategies
* Organisms have adapted to maximize growth rates in environments that lack limits or to maintain population size.

Survivorship curves show age distribution characteristics of species, reproductive strategies, and life history.
Reproductive success is measured by how organisms are able to grow up and reproduce.
Type I Survivorship Curve - Reproduction happens early in life.
* Low mortality at birth. Death rates increase with age.
Type II Survivorship Curve
* Individuals at all age categories have uniform death rates.
Type III Survivorship Curve
* Great numbers of offspring and reproduce for most of their lifetime.

Many different factors affect the human population.
Historical Population Sizes
* The rapid growth of population in the world over the past 100 years has been due to the decrease in death rates.
* The Human Population has had 3 surges of growth.
Distribution
  * In 1800, the majority of the world population was in Europe and Asia.
  * By 1900, 25% of the world population lived in Europe during the Industrial Revolution.
  * Now, most growth occurs in developing countries in Africa, Asia, Latin America.
Growth Rates and Doubling Times
* The 20th century showed the biggest growth in world population in human history.

The processes that have occurred during the past century.
Stage 1 - Pre-Industrial
  * Living conditions are severe.
  * Medical care is poor or nonexistent.
  * Food supply is limited.
  * Birth rates are higher due to high mortality rates.
  * Little population growth.
Stage 2 - Transitional
  * Occurs after the start of industrialization.
  * Medical care advances, sanitation is improved.
  * Cleaner water supplies, vaccinations, higher levels of education make death rates lower.
Stage 3 - Industrial
  * Urbanization decreases the economic incentives for large families.
  * Parents are discouraged from having large families due to cost.
  * Decreased birth rates due to jobs for women.
Stage 4 - Post-Industrial
  * Birth rates equal mortality rates.
  * Birth rates and mortality rates are low.
  * There is no population growth.
Strategies for Population Sustainability
  * Provide economic incentives for having fewer children
  * Provide free education, housing subsidies, monthly subsidies, free healthcare, higher pension benefits, tax incentives, or other economic incentives for women with one or two children.
  * Provide more job and employment opportunities to women.
  * Provide government family-planning services.
  * Increase economic development in developing countries.
  * Improve prenatal and infant health care.

Biodiversity - Earth’s biological diversity is crucial to the continued vitality of agriculture and medicine. Human activity is bringing organisms to extinction throughout the word.
Coastline and Oceans - Ocean fisheries are being exploited.
Forests - Half of the world’s original forests have been lost. Forests provide $400 Billion a year and are vital to maintaining healthy ecosystems.
Food Supply and Malnutrition - ¼ of the world today is malnutrition. The issue is the world cannot produce enough food.
Freshwater - Demand for freshwater is soaring as the population grows.
Global Climate Change - Earth’s surface is warming due to greenhouse gases, largely from burning fossil fuels.
Public Health and Increase in Disease - Unclean water kills 12 million people yearly. Air pollution kills 3 million yearly.
Unequal Distribution of wealth and governmental priorities - Rapid population growth can make it politically difficult for countries to raise standard of living.