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Transcript of Population Population Biology and Human Population Essential Question: How many people can...
PopulationPopulation Biology and
Human Population
Essential Question: How many people can sustainably
live on Earth?
Objectives
Students will:
• Apply the power of exponential growth to population problems
• Perform calculations involving doubling of populations (rule of 70)
• Draw a J and S curve and explain the difference between them
• Describe environmental resistance and discuss how it can lead to logistic growth
Objectives, continued
• Define and calculate: fertility rate, birth rate, life expectancy, death rate, population density, and survivorship
• Compare and contrast density-dependent and density independent events
• Explain the results of habitat fragmentation
• Explain how genetic drift, founder effect, and bottleneck effect impact populations
Dynamics
• Exponential growth: Unlimited resources and lack of predators results in unrestricted increase in a population size
• Biotic potential of a population is growth that would occur in absence of interfering factors
• Such organisms are generalists: quantity of individuals ensures survival of some Classic J-curve
World Population Doubling Time Change
First doubling: 1 – 2 billion _________ yearsSecond doubling: 2 – 4 billion _________ yearsThird doubling: 2.5 – 5 billion _________ yearsFourth doubling: 3 – 6 billion _________ years
What is happening to doubling time?
Population doubling
• Exponential growth results in doubling of the population.
• Example: The human population doubled from 2.5 billion to 5 billion between 1950 and 1990 – 40 years
• 70 ÷ r = Doubling time, where r is the percentage growth rate. This is called the RULE OF 70. (It comes from the natural log of 2, which is .70)
• Apply the rule: If the world population doubled in 40 years, what was the growth rate between 1950-1990?
• Use: Doubling time is used by countries to predict the need for resources and infrastructure and to aid in planning.
Limits
• Carrying capacity – maximum number of individuals an ecosystem can support
• Some species naturally limit their population growth when resources are limited
• Logistic growth curve – appears as an S, illustrates population size limited by resource availability
• Other species experience oscillating cycles of growth and decline
J-curve
Oscillation curvesPredator and prey populations often oscillate. Think about it. Host and parasite populations oscillate in a similar manner.
Be familiar with this concept.
Overshoot / Crash
Some species over-reproduce which can lead to a population crash – case study St. Matthew Island
Reproductive Strategies
r and K strategists
- K strategists
- r strategists
Factors that change population
• Nutrition, climate, soil, water are required
• Fecundity: the ability to reproduce
• Natality: production of new individuals
• Total Fertility Rate: measure of offspring produced in an average female’s life time
• Crude Birth Rate: number of births / thousand individuals
• Life expectancy: the number of years an individual is expected to live
• Life span: the longest period of time an organism reaches
Factors that change population
• Population density: number of individuals per square mile or kilometer
• Mortality rate: death rate of a population
• Crude Death Rate: number of deaths / thousand
• Immigration: population growth by individuals coming in
• Emigration: population decrease by individuals exiting
• Migration: movement of populations
• Replacement Rate: the number of offspring required for a couple to replace themselves (accounts for deaths)
Factors that regulate population
DENSITY INDEPENDENT
• Abiotic factors
• Natural disasters, weather, climate change over time
DENSITY DEPENDENT
• Biotic factors
• Predator-prey, territoriality
• Stress, crowding, disease
Conservation Biology
• What is Conservation Biology? A multidisciplinary science that has developed to address the loss of biological diversity.
• Why should we be concerned about conserving biodiversity? For the first time in Earth’s history, a single species, Homo sapiens, could cause a mass extinction. The main cause of loss of biodiversity is loss of habitat caused by human activities.
• What is Phytoremediation? The use of plants and soil bacteria to reduce the concentrations of toxic chemical compounds in the environment. Phytoremediation is widely accepted as a cost-effective environmental restoration technology.
• Is it possible to restore rainforests?
• How to save endangered species
Demographic transition
• Theory of growth and change in population and its characteristics as a result of industrialization
• 4 distinct phases
• Modeled with a graph in which you can see the following three changes over time:• birth rate• death rate• actual population
Demographic transition graph
Population on the Y axis, Time on the X axis.
Phase analysis
• Why are birth and death rates high in Phase I (Pre-industrial)?
• Why does death rate plummet in Phase II (Early Transitional)?
• Why does birth rate begin to decrease in Phase III (Transitional)?
• Why does the population remain high in Phase IV (Industrial) when birth and death rates are low?
• Is there a Phase V? What might it look like?
Phase analysis 1
Thanksgiving Population Project
Research one country’s demographics and report on:1. Population2. Birth rate3. Death rate4. Infant mortality rate5. Life expectancy6. Growth rate 2013 / 19957. Education levels8. Primary Industries (1-3)9. Employment levels10.Income per capita11.Government Type12.Key current events (1-3)
13. State the Demographic Transition Phase your country is in.14. Cite evidence to support your assertion.
Rubric
• Information: concise, up to date, accurate, complete
• Illustrations: demographic transition, population age structure diagram, photos showing life in your country
• Audience: Presentation is professional, interesting, compelling…. makes audience want to write an award-winning screenplay with this country as a setting…. (or visit, or join the Peace Corps)
Logistics
• FORMAT? • Add a page to APESlahs2013.wordpress.com• Poster• Power point
• Where to get info? • http://populationpyramid.net/• https://www.cia.gov/library/publications/the-world-factbo
ok/
• How many students per presentation?
Due date: Monday, December 2Email or text me with questions
Thanksgiving HW
• Define all terms in this ppt
• Population Math Problems B 1-5
• Read and summarize 3 articles on Conservation Biology
• Population Project
• Meet Wednesday, November 27 from 10-noon
Resources
• http://www.worldometers.info/world-population/
• http://www.census.gov/popclock/
• http://worldof7billion.org/
• http://www.worldof7billion.org/index.php/student_video_contest
• http://populationpyramid.net/
• https://www.cia.gov/library/publications/the-world-factbook/