Change over time……Change over time…..

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!

Notes: How living things vary

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

Armadillo found in

Argentina

Armadillo

found in

Texas

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…

There are more than 35,000 known species of spiders, including over 800 tarantula

species.

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

Successful reproductionOrganisms must reproduce to pass their genes to the

next generation.

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 -