Population Ecology

 Pop. Density  # organisms per unit area  Pop. Ranges  Areas occupied by a species  Spatial Distribution  Spacing pattern of individuals within the area  3 types:

Uniform Random Clumped

 2 types: 1) Density independent ▪ Usually abiotic, ex. Natural disasters 2) Density dependent ▪ Usually biotic (ex. Disease) ▪ Only relevant when density is high ▪ What are some others examples?

 Natality = birthrate Mortality = death rate  Determined by  (Natality + Immigration) – (Mortality + Emmigration)  Pos. = increase  Neg. = decrease

 Causes of increase:  Causes of decline:

 Exponential Growth Model  Constantly increasing growth  “J” shape  Occurs briefly when colonizing

 Logistic Growth Model  Exponential with a limit (carrying capacity) ▪ Carrying capacity = environment’s long-term max ▪ Limiting factor stops growth ▪ “S” shape

 r = rate of growth (+ or -)  K = carrying capacity  N = number of organisms

 R (rate) strategy:  Have lots of offspring quickly (short lifespan)  Usually small organisms in unstable environments  K (carrying capacity) strategy:  Have few offspring slowly (long lifespan)  Usually large organisms in stable environments

 Demography: study of human population  Human Pop growth  Human pop was stable for most of history (<1B)  Since around 1500 pop grew exponentially (7B)  Why?

 Technology advances (medicine, agriculture)  Allowed more people to live and longer  Pop growth is slowing

 Nearly all growth is in developing nations  Demographic transition occurring:  Poorer countries move from high to low birth and death rates  Most growth occurs in the middle ▪ Death rates fall before birth rates do usually  Zero Pop Growth this century is likely

 More young people = more growth  More old people = decline

 The Earth cannot sustain unlimited people  The # sustainable depends on ▪ total resources ▪ resources used/person  Technology can affect resource amounts/needs  Developed countries use FAR more resources/person

1. A 2. B 3. C 4. D A. disease B. fire C. flooding D. weather 4.1 Formative Questions Which is a density-dependent factor?

1. A 2. B 3. C 4. D A. competition B. extreme cold C. parasites D. predation 4.1 Formative Questions Which is a density-independent factor?

1. A 2. B 3. C 4. D A. emigration B. predation C. available nutrients D. extreme temperatures 4.1 Formative Questions Which factor can limit the carrying capacity of a population?

1. A 2. B 3. C 4. D 4.2 Formative Questions A. bioinformatics B. demography C. ecology D. ethnography The study of the size, density, distribution, and movement of the human population is _______.

1. A 2. B 3. C 4. D 4.2 Formative Questions A. decreased agriculture B. famine and wars C. setbacks in medicine D. voluntary population control Which is a primary reason for the decline in the percent growth of the human population after 1962?

1. A 2. B 3. C 4. D 4.2 Formative Questions A. CDC B. HPG C. PGR D. ZPG What will happen to the human population when the birthrate equals the death rate?

1. A 2. B 3. C 4. D A. emigration B. imitation C. immigration D. migration Chapter Diagnostic Questions What term is used to describe the number of individuals moving into a population?

1. A 2. B 3. C 4. D Chapter Diagnostic Questions B. number of organisms in an area C. characteristics of a population D. manner in which a population grows A. pattern of spacing of a population in anarea What is population density?

1. A 2. B 3. C 4. D Chapter Diagnostic Questions A. when birth rate equals death rate B. when death rate exceeds birth rate C. when birth rate exceeds death rate D. when there are zero births When does zero population growth occur?

1. A 2. B 3. C 4. D A. exponential B. spatial C. genetic D. logistic Chapter Assessment Questions Which type of population growth model does this graph represent?

1. A 2. B 3. C 4. D A. India has very little land for farming. B. Germany is smaller per acre than the United States. C. More land is used to support an individual in the United States. D. A person in Indonesia requires more land than a person in Brazil. Chapter Assessment Questions Based on the information in the graph, infer which statement accurately represents the information provided.

Use the graph to explain the growth of the mice population. Chapter Assessment Questions

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. Chapter Assessment Questions

1. A 2. B 3. C 4. D A B. 23 C. 230 D 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?

1. A 2. B 3. C 4. D Standardized Test Practice A. density B. dispersion C. logistic spacing D. spatial distribution The ecologist finds that over a 1000m 2 plot of tundra, lemmings tend to concentrate in clumps in drier areas. What is the term for this pattern of spacing?

1. A 2. B 3. C 4. D Standardized Test Practice A. It is density-dependent. B. It is limited by biotic factors. C. It has a limited spatial distribution. D. It is randomly dispersed in the environment. 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?

1. A 2. B 3. C 4. D Standardized Test Practice Why does the population growth level off at 10,000? A. Biotic factors have made survival difficult. B. The population has reached its carrying capacity. C. Density-independent factors have slowed the growth of the population. D. Immigration into the population has reached the maximum limit.

1. A 2. B 3. C 4. D Standardized Test Practice Which organism is the best example of a k-strategist? A. wolf B. grasshopper C. rabbit D. whale