1 / 18

TOPIC 2F How Populations Grow

TOPIC 2F How Populations Grow. Characteristics of Populations A. Geographic Distribution – Range or Area where species lives. B. Density - Number of organisms in an area Growth Rate - How fast # of organisms increases or decrease

stevie
Download Presentation

TOPIC 2F How Populations Grow

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. TOPIC 2F How Populations Grow

  2. Characteristics of Populations • A. Geographic Distribution – Range or Area where species lives. • B. Density - Number of organisms in an area • Growth Rate - How fast # of organisms increases or decrease • Age Structure - # of individuals within each age range

  3. Geographic Distribution – • Every organism has a specific set of needs such as type of food, type of shelter, type of breeding grounds. As a result each organism has a different requirement for space and ecosystem type. • Ex: Range of Bacteria – 1 apple • Range of a Whale – ThePacific Ocean

  4. Population Density • For any given species population density can change with geographic region

  5. Example: Saguaro cactus densities shown below are different. 1/area 5/area

  6. C. Population of Growth 1. Factors that influence population size: A. Birth rate - # of births in a given time B. Death Rate - # of deaths in a given time C. Individuals moving in (Immigration) D. Individuals moving out (Emigration)

  7. 2. Types of Growth: • Exponential Growth – (unlimited growth) When individuals within a population reproduce at a constant rate. • At first the size of population increases slowly • Rate speeds up once a high level of individuals have reached reproductive age. • Occurs when there is no limitation on resources

  8. B. Logistic Growth – Growth that is limited by resources. • Growth is initially exponential • Resources become less available growth slows or stops to the CARRYING CAPACITY

  9. Carrying Capacity – The largest number of individuals that a given geographic region can support.

  10. D. Age Structure- How many individuals of each age group make up a population.

  11. II. Limits to Population Growth Remember from last chapter: A limiting nutrient prevents an individual from growing. Ex: Nitrogen, Phosphorus A limiting factor prevents a population from growing.

  12. Types of Limiting Factors A. Density dependent limiting factors only limit growth rate of a population when the number of organism in an area is large. Examples: 1. Competition 2. Predation 3. Parasitism 4. Disease

  13. Competition – struggle for resources becomes greater with more individuals. • Predation – An increase in # of prey is followed by an increase in # of predators. • 3. Parasitism and Disease – Spread quickly through dense populations.

  14. Density independent limiting factors limit a population regardless of density • Examples: • Natural disaster such as storm, flood, or drought, clear cutting forests, damming a body of water

  15. III. Human Population Growth- For most of human existence population increased slowly because of limiting factors but increased rapidly in the last 500 years. Industrial Revolution begins Agriculture begins Bubonic plague Plowing and irrigation

  16. In the year 1900 the human population was 1.6 billion people • By the year 1999 the human population reached 6 billion people. • Scientists estimate the population will increase to 9 billion by 2050 • Can the human population grow like this forever?

  17. What could be the limits to growth of the human population? Earth’s resources are limited. Therefore population growth cannot continue exponentially. But we don’t know for certain when population will exceed resources.

  18. We can analyze graph data on the past human population and the projections for the future to determine how the rate of human population growth has been changing.

More Related