Darwin’s Theory

Ch. 6

Section 1

Learning Target

• I can describe important observations Darwin made on his voyage and explain how natural selection leads to evolution.

Charles Darwin

• Darwin was 22 years old when he set sail on the British ship HMS Beagle in 1831.

• A naturalist on the ship. (someone who studies the natural world).

• Observed many types of plants and animals and wondered why they were so different from the plants and animals in England.

• Led to the theory of Evolution by Natural Selection.

Darwin’s Observations

• Included…

• Diversity of living things, remains of ancient organisms, and characteristics of organisms on the Galapagos Islands.

Diversity and Fossils

• Darwin Noticed that animals were diverse and that they adapted to the environment in which they lived in.

• Fossil- preserved remains or traces of an organism that lived in the past.

Galapagos Organisms

• Many similarities were found between the Galapagos Organisms and the South American Organisms. (plants and animals)

• There are differences too. • Ex. Galapagos iguanas have longer claws

than South American.

> This is so they can grip on the slippery rocks on the cost.

Adaptations

• Finches beaks varied between islands.

• Some had narrow beaks for eating insects

• Others had wide beaks for eating seeds.

• Adaptation: trait that helps an organism survive and reproduce.

Evolution

• When animals arrived on the Galapagos Islands they had to adapt to new conditions and environment.

• The species gradually changed over many generations.

Natural Selection

• Darwin’s Book “the Origin of Species” proposed that evolution occurs by means of natural selection.

• Natural Selection: process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species.

Natural Selection with turtles

• Overproduction: Turtles lay many eggs, not all of the young survive.

• Variation: each turtle has slightly different traits. • Competition: turtles compete with one another. A

faster turtle may escape a predator. • Selection: variation such as speed make some

turtles better able to survive in their environment. • Survival and Reproduction: only few turtles

survive long enough to reproduce. The offspring may inherit the favorable traits of the parents.

Learning Target

• I can describe important observations Darwin made and explain how natural selection leads to evolution.