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/