Chapter 8 Population Change

1. Chapter 8Population Change

2. Overview of Chapter 8 • Principles of Population Ecology • Reproductive Strategies • The Human Population • Demographics of Countries • Demographics of United States

3. Principles of Population Ecology • Population Ecology • Study of populations and why their numbers change over time • Important for • Endangered species • Invasive species • Population • Group of individuals of same species living in the same geographic area at the same time

4. Population Density • Population density • The number of individuals of a species per unit area or volume at a given time • Ex: minnows per Liter of pond water

5. Change in Population Size

6. Change in Population Size

7. Death rate Growth rate Emigration rate Birth rate Immigration rate Calculating Population Change CRUDE BIRTH/DEATH RATE are calculated per 1000 people r = (b – d) + (i – e)

8. Maximum Population Growth • Intrinsic Rate of Growth (Biotic Potential) • Growth rate under ideal conditions • J- Shaped Curve (exponential growth)

9. Environmental Resistance • Environmental limits (resistance) • Prevent indefinite reproduction • Unfavorable food, water, shelter, predation, etc. • Carrying Capacity (K) • Maximum # of individuals an environment can support • Causes leveling off of exponential growth • S- shaped curve of logistic population growth

11. Check for understanding • 4 - I can explain to my peers why populations cant grow in size forever. • 3 - I understand what limits populations from growing in size unstopped. • 2 - I understand carrying capacity, but need more practice. • 1 - huh? Exponential growth? Carrying capacity?

12. Population Crash • Overshooting carrying capacity can lead to population crash • Abrupt decline in population density

13. Factors That Affect Population Size • Density Dependent Factor • Factor whose effect on population changes as population density changes • Examples: • Predation • Disease • Competition • Sometimes cause Boom-or-Bust Population Cycles

14. Boom-Or-Bust Population Cycles

15. Case Study- Predator Prey Dynamics on Isle Royale • As wolf population increases, moose population decreases (and vice versa)

16. Factors That Affect Population Size • Density Independent Factors • Factors that affects population size, but is not influenced by changes in population density • Examples: • Killing frost • Severe blizzard • Fire

17. Check for understanding • 4 - I can explain to my peers different ways that populations increase in size and factors that limit uncontrollable population growth. • 3 - I understand different ways that populations grow and limitations to their growth. • 2 - I understand how exponential growth, boom and bust, and carrying capacity, but I need more practice. • 1 - I am lost population growth.

18. Reproductive Strategies

19. Survivorship

20. Some populations fit two curves • Herring Gulls • Type III (young) & Type II

21. Check for understanding • 4 - I can explain to my peers how reproductive strategies vary from survivorship types. • 3 - I understand how reproductive strategies vary from survivorship types . • 2 - I understand, I think, but need to review my notes on reproductive strategies and survivorship types. • 1 - Aren’t all organisms the same????

22. Human Population • Demography • Science of population structure and growth • Human Population is J-shaped curve • Thomas Malthus • food for people??  famine & disease!!! • better crop yields

23. Human Population

24. Population Increase in Mexico

25. Projecting Future Populations • Population is increasing; why is death rate going down? • Growth rate (r) has started to decline • Zero-population growth: birth rate and death rate are equal (S –shaped curve) • Projections for 2050 – variation due to fertility rate of less developed countries • Low = 7.7 billion • High = 10.6 billion • Most likely = 9.1 billion

26. Demographics of Countries

27. Highly developed countries – Ex: US, Japan, Germany – • low birth rates, low infant mortality rates (6% US; 54% world), long life expectancy (77 US, 67 world), high per-capita GNI PPP ($34,000, $7,000) • Developing countries: • moderately developed countries (Ex: Mexico, Thailand) – high infant mortality/birth rates, but declining • less developed countries (Bangladesh, Niger, Ethiopia)

29. Growth rate • Doubling time!! – amount of time for an area to double = 70/r (r = growth rate as %) • Which type of country has shorter doubling time? • Replacement-level fertility – typically 2.1 children • Total fertility rate (world) is above replacement level (about 2.5) • Impacting factors: infant mortality rate, population momentum by ## of young females, need/lack of need for children to work (rural), education (especially of women!!)

31. Check for understanding • 4 - I can explain to my peers zero population growth, total fertility rate, replacement level fertility, and doubling time. • 3 - I understand zero population growth, total fertility rate, replacement level fertility, and doubling time. • 2 - I understand, I think, but need to review my notes on zero population growth, total fertility rate, replacement level fertility, and doubling time • 1 - I understand some of the terms, but not all.

32. Demographic Stages • Pre-industrial Stage • Birth and death rates high – poor medical care, limited food supply • Modest population growth • Transitional Stage • Lowered death rate – higher education/improved conditions • Rapid population growth • Industrial Stage • Birth rate decline – urbanization decreases economic reason for many kids, women educated/work, retirement safety nets reduce it • Population growth slow • Post Industrial Stage • Low birth and death rates • Population growth very slow

33. Demographic Stages

35. Age Structure • The number and proportion of people at each age in a population

36. Demographics of Specific Countries

37. World-wide • 29% of human population is under age 15 • Could cause large increase in birth rates

38. Check for understanding • 4 - I can explain to my peers all the different demographic stages, why they occur AND how to read age structure graphs. I should just drop out of HS now . • 3 - I understand all the different demographic stages, why they occur AND how to read age structure graphs . • 2 - I understand demographic transition and age structure graphs, BUT….. • 1 - I am lost and need to hear it all again.