Download Populations

Bellringer: 4/22/15
1.What do you think is
happening to the
human population?
2.STOTD
The Human Population,
and Biodiversity
Chapters 9 & 10
The Human Population
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Since 1800, the human
population has grown
exponentially
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Because
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Produced More Food
Good Hygiene
It’s estimated, we have
overshot Earth's Carrying
Capacity
The Human Population
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The Human Population
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Demography
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Study of populations and things affecting growth
• Usually human populations
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Predict what populations will look like in the future
• 4 main tools used to make the predictions
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The Human Population
1.
Age Structure
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Distribution of ages in a population
Shown using Population Pyramids
High Growth Rates = More Young People
Low Growth Rates = Even Distribution of Ages
The Human Population
2. Survivorship
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Type I
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Most live to be very old
Type II
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Percentage of newborns, likely to survive to a given age
3 types
50/50 Chance of Death
Type III
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Most die as very young
The Human Population
3. Fertility Rate
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Number of babies born each year per 1,000 women
Populations grow when the Fertility Rate is
above the Replacement Level
Replacement level
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Average number of kids parents must have to “replace”
themselves when they die
~ 2.1
The Human Population
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The Human Population
4. Migration
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Movement of individuals from 1 location to another
Immigration
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Emigration
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Movement into an area
Movement out of an area
Accounts for a big part of population change
Developed nations would have NO population growth
without migration
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The Human Population
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Recent population changes seem to be crazy
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Since 1850 the U.S. population has grown from 20 to
300 million people
By 2050 growth will have completely stopped
To explain these trends, demographers created…
end
The Human Population
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Demographic Transition
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Theory that Industrial Development causes
Economic and Social Progress, which then affects
population growth
4 stages
The Human Population
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Stage 1- Preindustrial
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High birth and death rates
Stable population
Models population growth until the 1700’s
The Human Population
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Stage 2- Transitional
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Death rates decline
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Hygiene, nutrition,
education
Population Explosion
Scientific Revolution,
the Enlightenment
The Human Population
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Stage 3Industrial
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Slower growth
rate
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Fewer births
Population
Stabilized
The 20th century
The Human Population
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Stage 4- Postindustrial
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Birth rate drops below replacement level
Population decreases
The Human Population
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The D.T. shows 2 factors for declining birth rates:
Increasing Education
Economic Independence for Women
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Fertility Rate for:
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Developed countries = 1.6
Developing countries = 3.1
Remember: Replacement Level ~ 2.1
The Human Population
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Rapid Pop. Growth = Environmental Problems
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Natural Resources and Modern Infrastructure are
Overwhelmed
Fuel Shortage- Can’t stay warm or cook
Unsafe Water- diseased water used for cooking/cleaning
Less Land- Expansion means taking over more land
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Wildlife, Agriculture, and Housing compete for the same land
The Human Population
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Countries are trying to slow growth:
U.N. is raising awareness of the dangers of over-population
China, Thailand, and India are trying to reduce fertility rates
– Advertising, Family Planning, Economic, and Criminal Incentives
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China started its 1 baby policy in 1979
Credits the prevention of 250 million births
 Only 36% of the population is under this rule
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The Human Population
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The Human Population
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Current World Population: ~6.79 billion
Fertility rates have been dropping since 1970
By 2050:
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World population will be ~9 billion
World fertility rates will be at the replacement level
Biodiversity
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Biodiversity
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The number of different species in a given area
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Tropical Rain Forest has very high biodiversity
Tundra has very low biodiversity
Essential for Survival
Biodiversity
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~1.7 million known species on Earth
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New species are discovered everyday
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Mostly insects!!!
Estimated there are more than 10 million species
Unknown species usually live in remote places or are part
of a kingdom that get little attention (fungi or bacteria)
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Biodiversity
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There are 3 main types of biodiversity:
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Species diversity
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Ecosystem diversity
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Different habitats and communities within ecosystems
Genetic diversity
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Differences between populations of the same species
Different genes within a specific population
Biodiversity
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Biodiversity keeps ecosystems stable
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Balanced Energy and Nutrient Cycles
Every species is dependent on at least 1 other species
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If species start dying off, how many will it take before the
ecosystem dies?
Biodiversity
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Some species are more critical to an ecosystem than others
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Known as Keystone Species
With out the keystone species the ecosystem will die
Biodiversity
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Genetic diversity is mandatory for a species to survive
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Organisms with the best traits survive = the species survives
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Evolution
If everyone had the same genes, when the ecosystem
changes everyone dies!!!
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Biodiversity
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As a population shrinks, the genetic diversity goes down
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This forces the species through a Bottleneck
Species starts with
10 different genes
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Species ends with
2 different genes
As the population recovers, genetic diseases are inherited
Biodiversity
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We take advantage of the biodiversity everyday
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¼ of all drugs are derived from plants
Almost all antibiotics are derived from fungi
Crops are cross-bred to grow faster, larger and to resist
disease
People pay money to look at pretty things (Ecotourism)
Bellringer: 4/27/15
1.How do humans take
advantage of
biodiversity?
2.STOTD
Biodiversity
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Throughout history there have
been mass extinctions
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Many species die off in a short time
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Due to Natural Disasters
Millions of years to recover
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Biodiversity
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Estimated that from 1800 to 2100, 25% of all
species on Earth may become extinct
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Species that can easily adapt and have large
populations are more likely to survive
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Unlike the past, this is because of humans
Cockroaches, Rats, Bacteria, …
Biodiversity
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Endangered Species
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Threatened Species
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A species, likely to die
off if not protected
A species, likely to
become endangered if
not protected
Biodiversity
Currently there are 1,964 protected species in the U.S.
– 1,214 animals & 750 plants
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In N.C. 64 species are protected
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37 animals and 27 plants
Since 1800, ~1,186 species have become extinct
worldwide
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These are just the ones we knew about before we killed them!
Biodiversity
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Humans cause extinctions in 4 main ways:
Habitat Destruction
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Need land to expand (farm, build houses, parking lots, ...)
Has caused ~75% of current extinctions
Biodiversity
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Invasive Exotic Species
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Species that are not native and are killing native species
Fire ants (1918), Kudzu (1876)
Harvesting, Hunting, Poaching
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Hunting to extinction
Taken for pets or other uses
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Pigeons, bison, medical herbs, exotic pets
Biodiversity
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Pollution
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Dumping into nature
DDT (a pesticide)
almost killed off the
Bald Eagle!!!
Biodiversity
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Areas with more diversity, are more important
These areas have lots of Endemic Species
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The 3 areas that are most important:
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Species that are only found in a small area
Tropical Rain Forests
Coral Reefs and Coastlines
Islands
Biodiversity
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Tropical Rain Forests
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Coral Reefs and Coastlines
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Provide food, protection, tourism revenue
60% of all reefs are in danger from humans
Islands
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Cover < 7% of the Earth surface
Over half of the world’s species live there
Species that colonized islands become isolated and can
evolve into new species
Darwin and the Galapagos Islands
Biodiversity
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A threatened a place of high biodiversity is called a
Biodiversity Hotspot
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Most hotspots have lost ≥ 70% of their natural vegetation
Biodiversity
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3 biodiversity hotspots are located in the US
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Florida Everglades
California Coast
Hawaii
Threatened by Human Population Growth
Biodiversity
What can we do to save biodiversity?
1. Save One Species at a Time
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Captive-Breeding
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Save Genetic Material
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Put species’ DNA on ice
Zoos, Aquariums, Parks, and Gardens
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Raise species in captivity, then release them into the wild
Living museums where species can survive
Biodiversity
2. Preserve Habitats and Ecosystems
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Save the Habitat = Save the Species
Sustainable Land Practices
3. Legal Protection for Species
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Endangered Species Act 1973
Habitat Conservation
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Some land developed, and some is preserved
Biodiversity
4. International Cooperation (IUCN)
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Red Lists- worldwide list of endangered species
CITES Treaty- illegal to trade endangered animals
Biodiversity Treaty- Must consider the
environment before building
World Wildlife Fund, Greenpeace, The Nature
Conservancy, US EPA, US FWS, Sierra Club,…
Biodiversity
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In Summary…
More Biodiversity = Healthier Ecosystem.
A balancing act between humans needs, and
what’s good for nature.
The best thing we can do:
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Become Educated on the Topic
And make smart choices for the future.
Biodiversity Checking on You
Quiz
1. What kind of species is critical to an ecosystem?
2. What type of diversity is mandatory for a species
to survive?
3. When a population gets smaller and loses genetic
diversity the species has just gone through what?
4. Cross-breeding crops allows us to do what? (name
1 thing)
5. By the year 2100 what percentage of species will
be extinct?
6. Who is the cause of this mass extinction?
Diversity Assignment
• Using the list on different types of diversity we
have made in class:
• Pick 5 different types, and use the National
Geographic magazines to illustrate the type of
diversity
• Make sure to label the pictures with the type of
diversity and a short description of the diversity