Chapter 3-Lesson 3 Notes

How Do New Species Evolve?

Charles Darwin

• Charles Darwin observed many unusual species of animals during a trip in 1835 through the Galapagos Islands.
• Darwin sailed on the HMS Beagle from 1831-1836
• Darwin noticed that similar species on different islands had adaptations that enabled them to survive in their different environments.

Example:

• Tortoises on different islands had shells of different shapes.  Their legs and necks of different lengths enabled them to find food or survive the environmental conditions on the various islands.

• Darwin also observed 13 different species of finches in the Galapogos  Islands.
• He noticed that the beaks of the finches on each island matched the available food.
• Through his research and observations, Darwin proposed the theory of natural selection.

Natural Selection is the idea that those organisms best adapted to their environment will be the ones most likely to survive. (Survival of the fittest!)

The main points of Darwin's theory are:

1. Organisms usually produce more offspring than can survive.
2. Competition exists among organisms. Those organisms that survive the competition are the only ones to reporduce and pass on their traits to offspring.
3. Organisms best adapted to their environments are the ones most likely to survivie long enough to reproduce.
4. Parent organisms pass traits on to their offspring.  Offspring usually look like their parents, but variations may occur.

Adaptations Over Time

• Certain traits may help an organism survive in its environment better than organisms that lack those traits.
• Long front teeth, claws, and sensative hairs are physical traits (structural adaptations) that help mole rats survive in their environment.

• A structural adaptation is an adaptation that involves body parts or color.
• Structural adaptations can take thousands or millions of years to evolve or they can evolve quickly.

New Species over Time

Populations are all the organisms of one species that live in a certain place.

• A population can become isolated when a barrier, such as a widened river, seperates some members of a population from others.
• Isolation can also occur when groups of animals migrate and become permanently seperated.
• When a population becomes isolated, each population adapts to its environment through natural selection.
• Successful traits are passed on to future generations.

Chapter 3-Lesson 2 Notes

How Do We Know Species Change Over Time?

Fossils-Clues to the Past

• Fossils are the remains of organisms that once lived.  They provide a record of the past life on earth.

• Fossils can be the preserved remains or an imprint of a once-living organism.

• Scientists use the fossil record together with what they know about present-day life on earth to draw conclusions, or "fill in the gaps"

• Scientists usually find only fossilized parts of an organism because the soft parts usually decay before the organism becomes fossilized .

Change Over Time

• Mutations,which are changes in an organisms DNA, may pass on helpful traits or some other adaptive advantage to an organism, which can be passed on to future generations.

• Over a long period of time, mutations can lead to a genetic change within a species.

• Evolution is a process that results in changes in the genetic makeup of a species over very long periods.

Unit A-Chapter 3-Lesson 1 Notes

What Are Adaptations?

Life Processes

1.) All living things carry out 6 life processes:

• Taking in energy
• Releasing energy in food
• Using Energy for body processes
• Producing and excreting wastes
• Responding to change in the environment
• Reproducing

2.) All organisms need energy to carry on life processes.

3.) Plants get their energy from the sun.

4.) Animals get their energy by eating other organisms

Adaptations

1.) A trait is a characteristic of an organism

Adaptations are inherited traits that help a species survive in its environment.

2.) Species do not adapt quickly.  Adaptations take a long time to develop.  Generation after generation reproduces before a trait becomes an adaptation of an entire species.