Evolution Darwin’s Voyage http://www.lucidcafe.com/library/96feb/darwin.html

Charles Darwin Was a naturalist – a person who studies the natural world. In 1831 the British naval ship HMS Beagle set sail from England on a five year long trip around the world. Darwin’s job was to learn as much as he could about the living things he saw on the voyage

Darwin’s Voyage

Darwin observed plants and animals he never seen before and wondered why they were so different from those in England. His observations lead to the most important scientific theories of all time: the theory of evolution by natural selection. http://www.darwinfoundation.org/

Darwin’s Observations Scientists now have identified more than 2.5 million species of organisms on Earth. A species is a group of similar organisms that can mate with each other and produce fertile offspring. Darwin observed new plants and animals at each stop in the voyage. He also observed bones of animals that died long ago. In 1835 the Beagle reached the Galapagos Islands and he observed some of the greatest diversity in life forms.

Similarities and Differences Although Darwin was surprised at how different the plants and animals were he also noted some similarities. (how they were the same) Both places had cormorants, for example, however they did not fly on the island.

The iguanas on the mainland had smaller claws and ate leaves. The iguanas on the islands had large claws that allowed them to keep their grip on slippery rocks and fed on seaweed. The iguanas on the mainland had smaller claws and ate leaves. http://www.geo.cornell.edu

He also noticed difference among organism from one island to the next. For example, one tortoise had dome-shaped shells and on another island the tortoise had a saddle-shaped shell. http://www.discovergalapagos.com/family/index.htm

Darwin inferred: A small number of different plant and animal species had come to the Islands from the mainland They might have been blown out during a storm or set adrift on a fallen log. Once on the island they reproduced Eventually, their offspring began to change

Adaptations Finches varied from island to island, in size and shape of their beaks Finches that ate insects had sharp , needlelike beaks Finches that ate seeds had strong, wide beaks. Beak shape is an example of an adaptation, a trait that helps an organism survive and reproduce

http://www.rit.edu/~rhrsbi/GalapagosPages/DarwinFinch.html

Evolution Darwin spent 20 years going over observations with other scientists From observations, he concluded that species gradually changed over many generations and become better adapted to the new conditions. The gradual change in a species over time is called evolution.

Darwin’s ideas are often referred to as the theory of evolution. A scientific theory is a well-tested concept that explains a wide range of observations. Darwin knew that evolution had occurred on the Galapagos Islands, but he did not know how it happened.

Natural Selection The Origin of Species – Darwin’s book that explained natural selection and evolution. Natural Selection – the 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. Factors that affect it are: overproduction, competition, variations and selection.

Variations- Any difference between a species is called a variation. Overproduction – Most species produce many more offspring than can possibly survive. In these species there is not enough resources for all to survive. Example: Sea turtles lay more than 100 eggs Competition - Since food and other resources are limited, offspring have to compete with each other to survive. Variations- Any difference between a species is called a variation.

Some variations make certain individuals better adapted to their environment. Those individuals are more likely to survive and reproduce. Over a long period of time, natural selection can lead to evolution. Helpful variations gradually accumulate in a species, while unfavorable one disappear.