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Population Density The number of organisms per unit area.

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Presentation on theme: "Population Density The number of organisms per unit area."— Presentation transcript:

1 Population Density The number of organisms per unit area

2 Which has a higher population size? 1. United States 2. New York City 0 of 5

3 Which has a higher population density? 1. United States 2. New York City 0 of 5

4 3 Types of Dispersion Draw Each 1. Uniform 2. Clumped 3. Random

5 3 Types of Dispersion 1) Uniform 2) Clumped 3) Random Ex: ______ __________________

6 Type of dispersion: White-Tailed Deer 1. Uniform 2. Clumped 3. Random 0 of 5

7 Type of dispersion: Black Bear 1. Uniform 2. Clumped 3. Random 0 of 5

8 Type of dispersion: Bison 1. Uniform 2. Clumped 3. Random 0 of 5

9 Type of dispersion: Mountain Lion 1. Uniform 2. Clumped 3. Random 0 of 5

10 Type of dispersion: Seeds dispersed by wind 1. Uniform 2. Clumped 3. Random 0 of 5

11 Type of dispersion: Caribou 1. Uniform 2. Clumped 3. Random 0 of 5

12 Limiting Factors Items that influence population growth “Limit” growth

13 1. Density-dependent limiting factors “Depends” on “density” a) Affect large, dense populations more than smaller, less- crowded populations

14 Density-dependent limiting factors i. Predation:  Fig. 5-7  Wolves & Moose on Isle Royale

15 Predator - Prey

16 Which increases first? 1. Predator 2. Prey 0 of 5

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18 Density-dependent limiting factors ii. Disease & Parasites:  Easily spread in large, dense populations

19 Density-dependent limiting factors iii. Competition:  Fig Compete for available resources  Food, water, space

20 iv. Crowding & Stress:  The higher population density, the more crowding and stress on individual organisms

21 2. Density-independent factors a) The density of the population DOES NOT MATTER b) It doesn’t matter if the population is 5 or 5,000, they will be affected

22 Density-independent factors i. Hot/Cold Weather ii. Fires iii. Floods/Hurricanes/Tornadoes iv. Human Activities – toxic waste spills, pesticides, deforestation

23 Population Growth Rate How fast a population grows It depends on 4 major factors

24 Population Growth Rate a) Natality = birthrate “neonatal intensive care” – newborns/preemies b) Mortality = death rate

25 Population Growth Rate c) Emigration – “exit” or leaving population d) Immigration – “in” or moving into a population

26 Population Growth Rate Population growth = Natality – Mortality + Immigration - Emigration

27 If natality is 10, mortality is 6, immigration is 3, and emigration is 2……the net effect on the population is… of 5

28 If the original population consisted of 10 individuals, what is the new population size? of 5

29 If birth rate > death rate 1. The population will increase 2. The population will stay the same 3. The population will decrease 0 of 5

30 If birth rate < death rate 1. The population will increase 2. The population will stay the same 3. The population will decrease 0 of 5

31 1. Exponential Growth (J–shaped Curve) a) If ideal conditions continue, the population will continue to grow rapidly b) Doubling and re-doubling a) 1, 2, 3, 8, 16, 32, 64, 128…….. c) Does NOT last long in nature – WHY?

32 Exponential Growth (J–shaped curve) d) This is current human population growth worldwide  How long can it last?  Discuss

33 Exponential Growth e) Draw graph

34 2. Boom and Bust a) As ideal conditions continue, population grows exponentially until it reaches a “peak” size (boom) and then crashes (bust) b) Ex: Rabbit population

35 Boom and Bust c) Draw graphs

36 Yeast Population Growth

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38 3. Logistic Growth (S-shaped curve) a) Exponential growth at first, eventually the population size levels off as the growth rate slows down b) Carrying capacity: Largest number of individuals that the environment can support

39 Logistic Growth c) Draw graph

40 Logistic Growth (S-shaped curve) d) Things that prevent the population from getting too big: Lack of food or water Home/shelter availability

41 Which of the following are NOT true about exponential growth? 1. It occurs at the beginning of logistic growth curves 2. It shows an S-shaped growth curve 3. It occurs only if ideal conditions exist 4. Populations have unlimited resources 0 of 5

42 Reproductive Patterns r-strategy: rate strategy  Generally are small  Short life spans  Produce many offspring  rat, fruit fly, locusts

43 Reproductive Patterns k-strategy: carrying capacity strategy  Larger organisms, long life span  Produces few offspring –better chance of survival  Take care of the offspring, usually for a long time  Kangaroo, elephant

44 Reproductive Pattern: Rabbits & Dolphins 0 of 5 1. Both r-strategists 2. Both k-strategists 3. r-strategist & k- strategist 4. k-strategist & r- strategist

45 Demography The study of human population size, density, distribution, movement, and birth and death rates

46 Demographic Transition A change in a population from high birth and death rates to low birth and death rates

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48 Demographic Transition Stage 1: birth rate & death rate Stage 2: birth rate & death rate Stage 3: birth rate & death rate Stage 4: birth rate & death rate Discuss & answer questions on Notes handout

49 Zero Population Growth Birth rate = Death rate

50 Age-Structure Diagram # of males & females in 3 age groups:  Pre-reproductive stage  Reproductive stage  Post-reproductive stage

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52 Age-Structure Diagrams Fig – predict future population sizes… Pyramid shaped (pre-reproductive larger)  Every age group about the same  Smaller at the bottom (pre-reproductive #’s smaller) 

53 Predict future population sizes: Pyramid shaped (pre-reproductive larger) 1. Population will increase 2. Population will stay the same 3. Population will decrease 0 of 5

54 Predict future population sizes: Every age group about the same size 1. Population will increase 2. Population will stay the same 3. Population will decrease 0 of 5

55 Predict future population sizes: Smaller at the bottom (pre-reproductive smaller) 1. Population will increase 2. Population will stay the same 3. Population will decrease 0 of 5

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57 Education & Demographic Transition 1. What does the first graph tell us? 2. What does the second graph tell us? 3. What is a key factor in reducing the overall worldwide population growth?


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