Chapter 4: Population Ecology

1. Essential Questions: EQ: How would changes in populations affect the flow of energy and matter in the ecosystem? EQ: How are populations regulated over time? EQ: How does the growing human population threaten the biosphere? Chapter 4: Population Ecology • Georgia Performance Standards: • Investigate the relationships among organisms, populations, communities, ecosystems, and biomes.

2. Chapter 4 Population Ecology Section 1: Population Dynamics Section2: Human Population

3. A laboratory jar containing a population of beetle larvae (mealworms) has reached a stable population size. We decide to add twice as much food per day to the jar, but this turns out to have no effect on population size. What is the most likely explanation? Warm-up:

4. Defined by different geographical boundaries appropriate to the questions being asked Important characteristics: Density Geographical Distribution Growth Rate Age Structure Populations

5. The number of individuals of a species per unit area or volume. Three factors can affect population size number of births number of deaths number of individuals that enter or leave the population Immigration(im-uh-gray-shun), the movement of individuals into an area, is another factor that can cause a population to grow. Emigration (em-uh-gray-shun), the movement of individuals out of a population, can cause a population to decrease in size. What is POPULATION DENSITY?

6. Population Ecology Chapter 4 4.1 Population Dynamics Population Density • The number of organisms per unit area Spatial Distribution • Dispersion is the pattern of spacing of a population.

7. Population Ecology Chapter 4

8. Population Ecology Chapter 4 4.1 Population Dynamics Population Ranges • A species might not be able to expand its population range because it cannot survive the abiotic conditions found in the expanded region. Common dolphin Pupfish

9. EQ: How are populations regulated over time?

10. Environmental factors that restrict population growth. Some limiting factors depend on the size of the population. Other limiting factors affect all populations in similar ways, regardless of the population size. Warm-up: Population Limiting Factors

11. 1. Imagine a small island that has a population of five rabbits. How might each of the following factors affect the rabbit population? a. climate b. food supply c. predation 2. Now imagine another small island that has a population of 500 rabbits. How would the same factors affect this population? 3. Which of the factors depend on population size? Which factors do not depend on population size? Warm-up: Population Limiting Factors

12. Population Ecology Chapter 4 4.1 Population Dynamics Population-Limiting Factors • There are two categories of limiting factors—density-independent factors and density-dependent factors.

13. Population Ecology Chapter 4 4.1 Population Dynamics Density-Dependent Factors • Any factor in the environment that depends on the number of members in a population per unit area is a density-dependent factor. • Biotic factors • Disease Population Biology • Competition • Parasites

14. Section 5-2 A Density-Dependent Limiting Factor Growth of Aphids Exponential growth Peak population size Rapid decline Steady population size Steady population size

15. Population Ecology Chapter 4 4.1 Population Dynamics Density-Independent Factors • Any factor in the environment that does not depend on the number of members in a population per unit area is a density-independent factor. • Weather events • Fire • Human alterations of the landscape • Air, land, and water pollution

17. 1. Name 2 types of limiting factors for a population. 2. Of the following factors with the potential to limit growth of a human population, which one is most density-independent? Mass drowning caused by hurricane flood Freezing deaths due to a shortage of housing Checkpoint!

18. Population Ecology Chapter 4 4.1 Population Dynamics Population Growth Rate • The population growth rate (PGR) explains how fast a given population grows. • The natality of a population is the birthrate in a given time period.

19. Population Ecology • All populations grow exponentially until some limiting factor slows the population’s growth. Chapter 4 4.1 Population Dynamics Exponential Growth Model • Exponential growth occurs when the growth rate is proportional to the size of the population.

20. Population Ecology Chapter 4 4.1 Population Dynamics Logistic Growth Model • The population’s growth slows or stops following exponential growth, at the population’s carrying capacity.

21. Population Ecology Chapter 4 4.1 Population Dynamics • A population stops increasing • when the number of births is less than the number of deaths • when emigration exceeds immigration.

22. Population Ecology Chapter 4

23. Population Ecology Chapter 4 4.1 Population Dynamics Carrying Capacity • The maximum number of individuals in a species that an environment can support for the long term is the carrying capacity. • Carrying capacity is limited by the energy, water, oxygen, and nutrients available.

24. Logistic growth Exponential growth S-shaped curve Limits on growth J-shaped curve No limits on growth Unlimited resources Constant growth rate Falling growth rate Concept Map Population Growth can be characterized by represented by characterized by represented by which cause a

25. Which of the following is NOT a condition for a population to reach exponential growth? presence of unlimited resources absence of predation and disease movement of individuals out of a population Checkpoint!!!

26. Population Ecology Chapter 4 4.1 Population Dynamics • The rate strategy, or r-strategy, is an adaptation for living in an environment where fluctuation in biotic or abiotic factors occur. • generally a small organism. • Short life span • Produces many offspring

27. Population Ecology Chapter 4 4.1 Population Dynamics • The carrying-capacity strategy, or k-strategy, is an adaptation for living in stable environments. • larger organism • Long life span • reproduce at an older age • Produces few offspring

28. Population Ecology Chapter 4 4.2 Human Population Human Population Growth • The study of human population size, density, distribution, movement, and birth and death rates is demography.

29. Population Ecology Chapter 4 4.2 Human Population Technological Advances • For 1000s of years, environmental conditions kept the size of the human population at a relatively constant number below the environment’s carrying capacity. • Humans have learned to alter the environment in ways that appear to have changed its carrying capacity.

30. Population Ecology Chapter 4 4.2 Human Population Human Population Growth Rate • Although the human population is still growing, the rate of its growth has slowed.

31. Population Ecology • Human population growth is not the same in all countries. Chapter 4 4.2 Human Population Trends in Human Population Growth • Population trends can be altered by events such as disease and war.

32. Population Ecology Chapter 4 4.2 Human Population Zero Population Growth • Zero population growth (ZPG) occurs when the birthrate equals the death rate. • #s at pre-reproductive, reproductive, and post-reproductive ages being approximately equal.

33. A population’s age structure is the number of males and females in each of three age groups: Population Ecology pre-reproductive stage, reproductive stage, and post- reproductive stage. Chapter 4 4.2 Human Population Age Structure

34. Population Ecology Chapter 4 4.2 Human Population Human Carrying Capacity • Scientists are concerned about the human population reaching or exceeding the carrying capacity. • An important factor is the amount of resources from the biosphere that are used by each person.

35. 1. Name 2 types of limiting factors for a population. 2. Of the following factors with the potential to limit growth of a human population, which one is most density-independent? Mass drowning caused by hurricane flood Due to overcrowding in Asian villages, many children did not survive Pop Quiz

36. 3. Which of the following is NOT a condition for a population to reach exponential growth? presence of unlimited resources absence of predation and disease movement of individuals out of a population Pop Quiz

37. Complete chapter 4 study guide in class. Classwork: