1 / 26

Populations

Populations. Chapter 5. 4 important characteristics of a population. Geographic Range Density and Distribution Growth Rate Age Structure. Geographic Range. Describes an area inhabited by a population Can vary Few cubic centimeters Kilometers of the ocean. Density and Distribution.

libby-goff
Télécharger la présentation

Populations

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. Populations Chapter 5

  2. 4 important characteristics of a population • Geographic Range • Density and Distribution • Growth Rate • Age Structure

  3. Geographic Range • Describes an area inhabited by a population • Can vary • Few cubic centimeters • Kilometers of the ocean

  4. Density and Distribution • Population density- the number of individuals per unit area.

  5. Formula for calculating population density • Population density= Number of individuals units area • Suppose there are 150 bullfrogs living in a pond that covers an area of 3 square kilometers. What is the density of the bullfrog population?

  6. 3 Factors that affect population size • # of births • # of deaths • # of individuals that enter or leave a population Population will increase or decrease depending on # of individuals added or removed

  7. What happens to the population when we… • Have more births than deaths? • Have more deaths than births? • Have equal amounts of births and deaths?

  8. Immigration • “im”= in • Migrate= to move from one place to another • Immigration is the individual movement into an area • Animal in search of mates and food in new areas

  9. Emigration • “E” = out • Migrate- to move from one place to another • Emigrate means individuals moving out of one place and into another • Young wolves and bears leaving as they mature • Shortage of food

  10. Two types of growth • Exponential growth • Individuals reproduce at a constant rate • Logistic growth • Occurs when a population growth slows or stops after a period of exponential growth

  11. Exponential Growth • Occurs under ideal conditions with unlimited resources • Think about exponents in math… • Starts slowly then sky rockets to infinity • Our graph would look like a J • Ex. Bacteria

  12. Logistic Growth • As resources become less available, the growth of the population slows or stops • S-shape curve • What we usually see in nature

  13. Carrying Capacity • The largest number of individuals that a given environment can support • The part of the logistic graph after the exponential growth… the flattening out • The point at which this flat line reaches the y-axis is the size of the population when the growth rate reaches zero • This doesn’t mean the population stops growing • Many factors slow the growth of plants and animals.

  14. Limiting Factors • Controls the growth of a population

  15. Density-Dependent Limiting Factors • Competition • Predation and Herbivory • Parasitism and Disease • Stress from Overcrowding

  16. Density- Independent Limiting Factors • Natural occurrences • Wildfires, drought, floods • It is difficult to say that a limiting factor act only in a density independent way.

  17. Human Population Growth • Exponential Growth • As life became easier the human population began to grow rapidly. • http://www.census.gov/main/www/popclock.html

  18. Thomas Malthus • Believed that human populations would be regulated by: • Competition (war) • Limiting resources (famine) • Parasitism (disease) • And Other density-dependent factors

  19. Demography • Examines the characteristics of human populations and attempts to explain how those populations will change over time.

  20. Age Structure and Population Growth

  21. Future Population Growth

More Related