1 / 17

Population Dynamics

Population Dynamics. - the study of how populations change in size, density and age distribution. Populations in Nature. Population Density Most populations clump together: for resources, for protection, for mating, for effective hunting Population Growth =

ziya
Télécharger la présentation

Population Dynamics

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. Population Dynamics - the study of how populations change in size, density and age distribution

  2. Populations in Nature • Population Density • Most populations clump together: for resources, for protection, for mating, for effective hunting • Population Growth = • (births + immigration) – (deaths + emmigration)

  3. R-selected species and Exponential Growth • R = intrinsic rate of increase = biotic potential • Each individual has maximum number of offspring • Population is well below available resources • Reproductive (life-history strategies) • Reproduce early in life span • Reproduce many offspring • Provide minimum care for offspring • Exponential Growth

  4. K-selected species and Logistic Growth • K = carrying capacity= environmental resistance • Maximum population an ecosystem can sustainably support • Population at or near available resources • Reproductive (life-history strategies) • Reproduce late in life span • Reproduce few offspring • Provide a lot of care for offspring • Logistic Growth

  5. Limiting Factors • Resources limit population growth • Density dependent limiting factors • Density-independent limiting factors

  6. History of the Human Population • Hunter Gatherer Societies (5 m.y.a. – 8,000 b.c.) • Food, water, shelter, etc.were limiting factors • Total population less than a few million • Rise of Agriculture (8,000 b.c. – 1800 a.d.) • Ability to store food improved lifespan • First major increase in population • Industrial Revolution (1800 – present) • Rapid population increase due to sanitation, medicine, and transportation technologies

  7. Changes in Population • Change in population = (births + immigration) – (deaths + emigration) • Age structure diagrams (population pyramids) Predict future population growth

  8. Survivorship Curves

  9. What factors determine fertility rate? • Fertility Rate = number of children a woman has • Total fertility rate • What determines fertility rate? • Cost of raising children and how early they begin work • Availability of private & public pension (retirement) • Urbanization: access to medical care, contraceptives education, and employment for women • Culture, religion, including average age of marriage • Availability of legal abortions

  10. What factors affect mortality rates? • Mortality rate = number of deaths • Indicators of quality of life: • Life expectancy • Infant mortality • What determines mortality rate? • Nutrition • Medical advances • Improved sanitation and safe water

  11. Demographic Transition • Stage 1: Pre-Industrial Age • High birth rate, high death rate • Stage 2: Agricultural/Industrial Age • Death rate declines: improved sanitation, nutrition • Stage 3: Industrial Age • Birth rate declines: social changes • Stage 4: Post-Industrial Age • Low birth rate, low death rate

  12. The Classic Stages of Demographic Transition Note: Natural increase is produced from the excess of births over deaths.

  13. Challenges of Population Growth • Infrastructure: public water, sewer, power plants, power lines, roads, schools, etc. • Clean water • Resource shortages (fuel, wood) • Agriculture can deplete soil • Urban sprawl: traffic, habitat destruction

  14. Population Structures by Age and Sex, 2005 Millions Less Developed Regions More Developed Regions Age 80+ 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 Male Female Male Female Source: United Nations, World Population Prospects: The 2004 Revision, 2005.

  15. World Population Growth Through History 12 11 2100 10 9 Modern Age Old 8 Iron Middle Bronze Stone Age New Stone Age Ages Age Age 7 Future 6 2000 Billions 5 4 1975 3 1950 2 1900 1 1800 Black Death — The Plague 2000 1+ million 7000 6000 5000 3000 1000 A.D. 4000 A.D. A.D. A.D. A.D. A.D. years B.C. B.C. B.C. B.C. B.C. B.C. B.C. 1 1000 2000 3000 4000 5000 Source: Population Reference Bureau; and United Nations, World Population Projections to 2100 (1998).

More Related