1. CHAPTER 52 POPULATION ECOLOGY

2. Characteristics  Density  Distribution  Size  Age Structure

3. Density  Direct Counts- –Larger, less numerous organisms  Plankton Population Sampling –Time x velocity x diameter = M 3 –Total # of plankton/ M 3 = # plankton per M 3 –75 plankton/0.5 M 3 = 150/M 3  Mark & Recapture- many animals  Aerial Surveys – –Line transects etc. –observe large areas, large animals by sight  Mist nets for migrating birds

4. Mark & Recapture # marked in 1 st catch = # recaptures in 2 nd catch Population total total # in 2 nd catch Population total total # in 2 nd catchOR: N = # marked in 1 st catch x total # in 2 nd catch # of recaptures in 2 nd catch # of recaptures in 2 nd catch # marked = 50 Total in 2 nd catch = 100 # recaptures = 10 N = 50 x 100/10 N = 500

5. Dispersion  How the individuals are arranged in the landscape.  Uniform – –all parts of the habitat suitable, but has intra- specific competition  Random –all parts of habitat suitable  Clumped- –Habitat is patchy or –Social behaviors

6. Dispersion

7. Population Size  Starting size of population  Add: Births and immigration  Subtract: Deaths and emigration  Gives the New population size,

9. Population Growth Time # Females Eggs/Female # Flies 11100100 2501005,000 32,500100250,000 4125,00010012,500,000 56,250,000100625,000,000 6312,000,00010031,250.000,000 715,625,000,0001001,563,500,000,000

10. Growth curve for field Mice in a cornfield Exponential Growth

11. Fig. 9.4, p. 201 Time (t) Population size (N) Exponential Growth  Biotic Potential – Pop. Grows as fast as physiology allows.  Unlimited resources  No pollution build up  Ideal conditions  Short lived period  Often quickly die out, colonize new areas  R selected species

12. Logistic Growth

13. Time (t) Population size (N) K Logistic Growth  Slower initial growth  Long –term stable pop. At carrying capacity (K).  K is size of pop. Area can sustain.  Growth slowed by limiting factors

14. Fig. 32.2

15. Population Limiting Factors  Density dependent factors –Competition –Predation –Stress/crowding –Waste accumulation –Disease –Space –Resources  Density independent factors –Weather/climate –Periodic disturbances

16. Population Life History Strategies R K

17. Type I vs Type III  Type III (R selected) –Short maturation & lifespan –Many offspring –No parental care –High death rate  Type I (K selected) –Long maturation & lifespan –Few offspring –Extensive parental care –Low death rate

18. Fewer, larger offspring High parental care and protection of offspring Later reproductive age Most offspring survive to reproductive age Larger adults Adapted to stable climate and environmental conditions Lower population growth rate (r) Population size fairly stable and usually close to carrying capacity (K) Specialist niche High ability to compete Late successional species elephantsaguaro K-Selected Species

19. r-Selected Species cockroachdandelion Many small offspring Little or no parental care and protection of offspring Early reproductive age Most offspring die before reaching reproductive age Small adults Adapted to unstable climate and environmental conditions High population growth rate (r) Population size fluctuates wildly above and below carrying capacity (K) Generalist niche Low ability to compete Early successional species

20. European Kestrals

21.  r selected –Population grows at biotic max –Lots of offspring –Little parental care –Reproduce early, often K selected –Population adapted to being at carrying capacity –Few offspring –Lots of parental care –Reproduce late, infrequently

22. Testing a hypothesis

23. Human Population Growth or Go Forth and Multiply

24. Human Population growth  For most of our history a logistic curve.  Currently exponential growth –Not uniform around the globe –Developing nations growing fastest  What has made the change possible? –Drop in death rate. Birth rate has fallen, not increased.  How long will this be sustainable?  Future predictions for growth?

25. Human Population Growth

26. World – Wide Trend??  Growth rates differ within and between countries:

27. Births per woman < 2 2-2.9 3-3.9 4-4.9 5+ Data not available Births per woman

28. Infant deaths per 1,000 live births <10 10-35 36-70 71-100 100+ Data not available Infant deaths

29. Fig. 11.3, p. 240 <1% 1-1.9% 2-2.9% 3+% Data not available Annual world population growth Population Growth

30. GNP per capita, 1998 Low income (Under $1,000) Middle income ($1,000–$10,000) High income (Above $10,000) Fig. 1.5, p. 9 Income and country

32. Rapid GrowthSlow GrowthZero GrowthNegative Growth General age structure diagrams

33. CanadaUnited States IndiaAustralia MexicoChina Males Females

34. Age FemalesMales 1955 20 Millions 24 1985 Millions 24 2035 Millions 2015 24 Millions Yellow= Baby Boomers USA age structure Diagrams

37. NOW WHAT?

38. Where we are:  1930, 2 billion  September 1999, 6 billion –3 people every second –250,000 every day –87 million every year –12 billion by 2050 –8 Billion- if slower rate

39. Influence on environment  More land for agriculture, resource exploitation  More land for cities, roadways, suburbs  Less fish in the sea for the food chain  Deforestation  Oil, gas won’t last forever  Pollution builds up  Better “green” technologies?  Heightened awareness, concern?  Better understanding of ecosystems?

40. Human disturbance Tropic of Capricorn Equator Predominantly natural Partially disturbed Human dominated Antarctic Circle Tropic of Cancer Arctic Circle Arctic Circle Human domination of landscape

41. Every second… 5 people are born and 2 people die, a net gain of 3 people.

42. Improved medical care has dramatically reduced infant mortality and mortality of women during labor.

43. Demographic transition  Larger urban families cost more, birth rate drops  Population now much larger, slows its growth rate  Influence of other (cultural, religious) pressures can slow birth rate decline  Women often lack freedom to determine family size, education employment opportunities

44. Demographic transition  Death rate (infant mortality) drops first  Birth rate remains constant  Population increases quickly  Economy transitions from agriculture to urban

45. Stage 1 Preindustrial Stage 2 Transitional Stage 3 Industrial Stage 4 Postindustrial births deaths relative population size lowincreasing very high decreasinglowzeronegative

47. 32 30 28 26 24 22 20 18 16 14 0 19101920193019401950196019701980199020002010 Births per thousand population Demographic transition DepressionBaby boom Baby bust Echo baby boom World War II Year USA demographic transition & population size

48. 4.0 3.5 3.0 2.5 2.0 2.1 1.5 1.0 0.5 0 1920193019401950196019701980199020002010 Births per woman Total fertility rates in USA 1917-2000 Baby Boom (1946-64) 1975 on ….Below native replacement rate- immigration keeps population growing

49. 1907 1914 New laws restrict immigration Great Depression Legal immigration to the United States between 1820 and 1997