1. Population Dynamics

2. Population Ecology Population: all the individuals of a species that live together in the same area Branch of ecology that studies the interaction between members within the same population

3. Characteristics of Populations 1.Birth and Death rates 2.Sex Ratios 3.Age Distribution 4. Density 5.Dispersion 6.Reproductive Strategies

4. Populations have characteristic birth/death rates 1.Natality - number of births Birthrate - number born in a given time 2. Mortality – number of deaths Deathrate - number that die in a given time

5. Sex Ratios Comparison in numbers of males and females Affects sexual reproductive success – in all species the number of offspring produced is tied more closely to number of females than males More mommas…more babies

6. Age Distribution Number of individuals of each age in the population Used to predict population growth rate

7. PRE- REPRODUCTIVE REPRODUCTIVE POST- REPRODUCTIVE

9. Population Density Number of individuals per unit of area 1 grizzly bear/ 10 square miles 24 students / classroom

10. High Density Low Density

12. Dhaka, Bangladesh 112,700 / sqmi

13. Population Density affects the availability of resources

15. Population Dispersion (Spacing) Dispersion – way in which individuals are spread out, or spaced, in the area they live in.

16. 3 Types of Dispersion

17. Clumped dispersion Grouped around resource Most common pattern in nature Advantages: Offer protection against predators Easier to find mates

18. Uniform Dispersion Even Spacing Advantages Reduces energy wasted in competition Individuals hold territories

19. Random Dispersion Organisms distributed in no real pattern Not common – only occur where: Resources are found evenly throughout an area No significant much competition

20. Watch Video Population Spacing

21. Reproductive Strategies *R strategists *K strategists

22. R strategists  Short life span  Small body size  Reproduce early age  Have many young  Little/no parental care  Ex: cockroaches, weeds, bacteria

23. K strategists  Long life span  Large body size  Later reproductive age  Have few young  Provides parental care  Ex: humans, elephants

24. Factors that affect Population Size and Growth 1.Births - number of individuals born 2.Deaths – number of individuals who died 3. Immigration- movement of individuals into a population 4. Emigration- movement of individuals out of a population

25. Factors that affect Population Growth INCREASES TO POPULATION Births Immigration (In) DECREASES TO POPULATION Deaths Emigration (Exit)

26. Population Growth Rate is determined by: Birth Rate + Immigration Rate minus Death Rate + Emigration Rate Rate is amount per time period. Example: 100 babies are born/mth + 4 Immigrate in/mth - 14 die/mth + 1 Emigrate = 86/mth Growth rate = 89/mth

27. Immigration Emigration Natality Mortality Population Size + + - - Factors That Affect Population Growth

28. Population Growth Rate of population growth is directly determined by the amount of resources available Food Water Space Nesting/Breeding Sites Available Mates

29. Exponential Growth Occurs when resources are abundant and predators may be lacking J shaped growth curve Very few limits to growth Often occurs when species moves to previously uninhabited area. Ex. Invasive Stinkbugs

30. Logistic Growth Most environments have limited resources which limit population growth A typical growth pattern is slow (lag) growth, period of exponential growth, then a leveling as resources deplete and pop. gets to its carrying capacity S – shaped curve

31. Human Population Exponential Growth

32. Carrying Capacity Maximum number of individuals of a species that the environment can support

33. Carrying Capacity is dependent on environmental changes

34. Overshoot and Population Crashes Overshoot occurs when a population exceeds the long term carrying capacity of its environment. The consequence of overshoot is called a collapse, a crash or a die-off.

35. Limiting Factors Many factors affect the carrying capacity The factor that has the greatest effect in restricting the population growth is called the limiting factor.

36. Limiting factor Ex. 20 Rabbits live where they have enough water, nesting spaces, cover but only enough food for 10 rabbits. What’s the limiting factor?

37. Limiting factor – nitrogen fertilizer

38. 2 Groups of Limiting Factors Density–dependent limiting factors Density–independent limiting factors

39. Factors that Population Growth Density-dependent factors- Affect varies depending on population density. Greater population density, factor has greater affect. Smaller population density, factor has lessor affect.

40. Density Dependent Limiting Factors Competition – greater population density causes resources used faster Predation – Greater population density makes it easier on predators to get prey Parasitism – When organisms live more closely together/ densely packed, it allows for easier spread of parasites and disease

41. Density-independent factors- Factor whose affects does not vary with population density Ex. Temperature Drought Natural disasters – fire, volcano, tsunami, Habitat destruction by humans

42. Watch Video Population growth

43. Human Population Growth

45. What does the future hold for human population growth? When will human population growth outstrip the available resources Are we already living unsustainably???

46. Human Population Growth

47. Time unitBirthsDeaths Natural increase Year 130,013,274 56,130,242 73,883,032 Month 10,834,440 4,677,520 6,156,919 Day 356,201153,781 202,419 Hour 14,8426,408 8,434 Minute 247 107141 Second 4.11.8 2.3