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Today’s AgendaTues
3/18/14
1. Notes: How living things vary
2. Meet at Computer lab tomorrow – bring your earbuds/headphones
Get a paper
at the
front door!
When he was only 22 years old he sailed around the world from England.
His job was to learn as much as he could about the living things he saw on the voyage
Who was Charles Darwin?
HMS Beagle
Darwin’s VoyageI wonder why the species here are so different than those in England?
Darwin’s observations led him to develop a theory
His theory is known as the theory of evolution by natural selection
Darwin sailed from England to S. America and then to the Galapagos Islands
Darwin’s Observations
Darwin was amazed by the tremendous diversity, or variety of living things!!
Galapagos Islands
http://www.youtube.com/watch?v=TzAvFtQv3oQ
Galapagos Islands
They are found in different
locations around the island
If they are the same species of bird – why are the beaks
different?
Species – a group of similar offspring that can mate with each other and produce fertile offspring
These are all different types of
finch birds
http://www.youtube.com/watch?v=cW45C9BY1aU
If they are the same species of bird – why are the beaks
different?
Observations of diversity
Today scientists know that living things are even more diverse than Darwin could ever have imagined.
Scientists have identified more than 1.7 million species of organisms on Earth.
Hmmm…
Natural Selection
Natural selection is the process by which individuals with favorable traits survive and reproduce.
Darwin’s theory of natural selection can be described in four basic steps:
1. Overproduction2. Genetic variation3. Struggle to Survive4. Successful reproduction
Over time, the number of organisms with a trait that helps them survive or reproduce will increase in a population.
Over production
Organisms often have more offspring than will survive long enough to become adults.
Tarantula egg sack
Genetic Variation
Every individual has its
own combination of physical traits.
Some of these traits
improve survival and other traits lower the chances of survival in it’s environment.
No two individuals in a population are exactly alike.
Struggle to survive
Individuals in a population must compete for food, water, living space, and mates.
Some individuals may be killed by predators, or by diseases.
Tarantula hawk
Watching Natural Selection happen
Populations are always responding to changes in their environment.
Whether a new predator moves into an area or the climate changes, some individuals will be better able to adapt than others.
These individuals will be more likely to pass their traits to future generations.
Natural Selection and the
Peppered MothIn the early 1800’s scientists found that most of the peppered moths in England were light colored. Dark colored moths were rare.
The bark on the trees in Europe at the time were light colored.
The light colored moths were hard to see.
The dark peppered moths were easy to see.
England, Early 1800’s
Environmental changes alter the peppered moth population
During the 1850’s, the environment in Europe began to change. Thousands of factories began to burn coal and fill the air with smoke and dark soot.
The bark on the trees in Europe at this time began to become darker.
The dark colored moths were hard to see.
The light colored moths were easy to see.
Birds began to eat more light colored moths because they were easy to find.
England 1850’s
Pollution can affect human lives as well as the lives of other living things.
Smog has killed large numbers of people since the industrial revolution.
In 1952, nearly 4,000 people were killed when a heavy smog hung over London.
Environmental
Issues
Evolution of the whalehttp://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html
Explain the whale theory -