Population

PopulationPopulation Biology and

Human Population

Essential Question: How many people can sustainably

live on Earth?

ObjectivesStudents 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

timeDENSITY 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 conservin

g 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-factbook/

• 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-w

orld-factbook/