Chapter 4 Population Ecology

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

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

4. Population Ecology Chapter 4

5. Patterns of distribution Uniform Random Clumped

6. Clumped distribution • Clumped distribution is the most common in nature • found in environments that are characterized by patchy resources • Animals need certain resources to survive, and when these resources become rare during certain parts of the year animals tend to “clump” together around these crucial resources. • Organisms that usually serve as prey form clumped distributions in areas where they can hide and detect predators easily. • schools of fish aggregate to minimize the chance that any one fish will be eaten. • Hunting-- Hyenas, lions, and cheetahs hunt in packs • Humans exhibit a clumped distribution • Cities, towns, neighborhoods, households

7. Uniform Distribution • Also known as even distribution • Characterized by the maximization of distance between any two individuals. • Typically found in plants; they compete for a resource such as soil nutrients or moisture • Space themselves far apart in order to maximize the amount of resource consumption. I • Can also be a result of territorial behavior as in penguin colonies.

8. Random Distribution • Also known as unpredictable spacing • Least common form of distribution in nature • Occurs when the members of a given species are found in homogeneous environments in which the position of each individual is independent of the other individuals • Neither attract nor repel one another • Dandelion seeds are dispersed by wind, random distribution will often occur as the seedlings land in random places determined by uncontrollable factors.

9. 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

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

11. 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

12. 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

13. 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.

14. 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.

15. Exponential Growth Model Equation • dN = Change in population • dt = Change in time • r = rate of increase • N = # of individuals • r = b-d • b = birth rate (b = B/N) • d = death rate (d = D/N) • B= # of births • D = # of deaths

16. 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.

17. Logistic Growth Model Equation • dN = Change in population • dt = Change in time • r = rate of increase • N = # of individuals • K = Carrying Capacity • r = b-d • b = birth rate (b = B/N) • d = death rate (d = D/N) • B= # of births • D = # of deaths

18. Population Ecology Chapter 4 4.1 Population Dynamics • A population stops increasing when the number of • births is less than the number of deaths or when • emigration exceeds immigration. • Births < deaths • Emigration (exit) > immigration (into)

19. Population Ecology Chapter 4

20. 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.

21. Population Ecology Chapter 4 4.1 Population Dynamics Reproductive Patterns • Species of organisms vary in the number of births per reproduction cycle, in the age that reproduction begins, and in the life span of the organism.

22. 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. • Unstable environment • An r-strategist is generally a small organism. • Short life span • Produces many offspring • Little parental care • Example—spiders, flies, insects

23. Population Ecology Chapter 4 4.1 Population Dynamics • The carrying-capacity strategy, or k-strategy, is an adaptation for living in stable environments. • A k-strategist is generally a larger organism. • Long life span • Produces few offspring • Lots of parental care • Examples: Elephants, humans, Artic turns

24. 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.

25. Population Ecology Chapter 4 4.2 Human Population Technological Advances • For thousands 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.

26. 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.

27. 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.

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29. Population Ecology Chapter 4 4.2 Human Population Zero Population Growth • Zero population growth (ZPG) occurs when the birthrate equals the death rate. • The age structure eventually should be more balanced with numbers at pre-reproductive, reproductive, and post-reproductive ages being approximately equal.

30. 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

31. 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.

32. Population Ecology Chapter 4 Chapter Resource Menu Chapter Diagnostic Questions Formative Test Questions Chapter Assessment Questions Standardized Test Practice biologygmh.com Glencoe Biology Transparencies Image Bank Vocabulary Animation Click on a hyperlink to view the corresponding feature.

33. A B C D Population Ecology Chapter 4 CDQ 1 Chapter Diagnostic Questions What term is used to describe the number ofindividuals moving into a population? emigration imitation immigration migration

34. A B C D Population Ecology Chapter 4 CDQ 2 Chapter Diagnostic Questions What is population density? pattern of spacing of a population in an area number of organisms in an area characteristics of a population manner in which a population grows

35. A B C D Population Ecology Chapter 4 CDQ 3 Chapter Diagnostic Questions When does zero population growth occur? when birth rate equals death rate when death rate exceeds birth rate when birth rate exceeds death rate when there are zero births

36. A B C D Population Ecology Chapter 4 FQ 1 4.1 Formative Questions Which is a density-dependent factor? disease fire flooding weather

37. A B C D Population Ecology Chapter 4 FQ 2 4.1 Formative Questions Which is a density-independent factor? competition extreme cold parasites predation

38. A B C D Population Ecology Chapter 4 FQ 3 4.1 Formative Questions Which factor can limit the carrying capacity of a population? emigration predation available nutrients extreme temperatures

39. A B C D Population Ecology Chapter 4 FQ 4 4.2 Formative Questions The study of the size, density, distribution, and movement of the human population is _______. bioinformatics demography ecology ethnography

40. A B C D Population Ecology decreased agriculture famine and wars setbacks in medicine voluntary population control Chapter 4 FQ 5 4.2 Formative Questions Which is a primary reason for the decline in the percent growth of the human population after 1962?

41. A B C D Population Ecology Chapter 4 FQ 6 4.2 Formative Questions What will happen to the human population when the birthrate equals the death rate? CDC HPG PGR ZPG

42. A B C D Population Ecology Chapter 4 CAQ 1 Chapter Assessment Questions Which type of population growth model does this graph represent? exponential spatial genetic logistic

43. A B C D Population Ecology Chapter 4 CAQ 2 Chapter Assessment Questions Based on the information in the graph, infer which statement accurately represents the information provided. India has very little land for farming. Germany is smaller per acre than the United States. More land is used to support an individual in the United States. A person in Indonesia requires more land than a person in Brazil.

44. Population Ecology Chapter 4 CAQ 3 Chapter Assessment Questions Use the graph to explain the growth of the mice population.

45. Answer: If two adult mice breed and produce a litter and their offspring survive to breed, then the population grows slowly at first. This slow growth is defined as the lag phase. The rate of population growth begins to increase rapidly because the total number of organisms that are able to reproduce has increased. Exponential growth occurs when the growth rate is proportional to the size of the population. All populations grow exponentially until some limiting factor slows the population’s growth. Population Ecology Chapter 4 CAQ 4 Chapter Assessment Questions

46. A B C D Population Ecology Chapter 4 STP 1 Standardized Test Practice An ecologist estimates a population density of 2.3 lemmings per square meter of tundra. What would be the approximate number of lemmings over 1000 square meters of tundra? 0.23 23 230 2300

47. A B C D Population Ecology Chapter 4 STP 2 Standardized Test Practice The ecologist finds that over a 1000m2 plot of tundra, lemmings tend to concentrate in clumps in drier areas. What is the term for this pattern of spacing? density dispersion logistic spacing spatial distribution

48. A B C D Population Ecology Chapter 4 STP 3 Standardized Test Practice Brine shrimp are able to survive only in certain lakes that have a very high salt concentration. Which is the correct population characteristic of brine shrimp? It is density-dependent. It is limited by biotic factors. It has a limited spatial distribution. It is randomly dispersed in the environment.

49. A B C D Population Ecology Chapter 4 STP 4 Standardized Test Practice Why does the population growth level off at 10,000? Biotic factors have made survival difficult. The population has reached its carrying capacity. Density-independent factors have slowed the growth of the population. Immigration into the population has reached the maximum limit.

50. A B C D Population Ecology Chapter 4 STP 5 Standardized Test Practice Which organism is the best example of a k-strategist? wolf grasshopper rabbit whale