Change over time…… Change over time…..

Today’s Agenda Tues 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 Voyage I 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 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

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. Overproduction 2. Genetic variation 3. Struggle to Survive 4. 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 reproduction Organisms 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 Moth In 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 whale Explain the whale theory -