- 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.
- 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.
The main points of Darwin's theory are:
- Organisms usually produce more offspring than can survive.
- Competition exists among organisms. Those organisms that survive the competition are the only ones to reporduce and pass on their traits to offspring.
- Organisms best adapted to their environments are the ones most likely to survivie long enough to reproduce.
- Parent organisms pass traits on to their offspring. Offspring usually look like their parents, but variations may occur.
- 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.
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.