Chapter 15 Darwin’s Theory of Evolution Biology – Fall 2006 Mr. Holmes

Charles Darwin was the man with ideas that drove the theory of evolution. Darwin was an Englishman who set sail on a voyage on the H.M.S. Beagle. While on this trip he made numerous observations and collected data that led him to propose a revolutionary hypothesis.

Evolution is the change over time. A theory is a well-supported, testable explanation of a phenomenon that has occurred in the natural world. Most of Darwin’s observation come from the Galapagos Islands near South America.

One significant observation that Darwin made is the amount of diversity within a species. Another observation was the fact that not all the same species lived in the same places (diversity of species in different locations)

His observations were supported by fossils that he discovered. Fossils are preserved remains of ancient organisms. Some of the animals that Darwin observed were finches (beak shape), beetles and turtles (shell shape).

Before Darwin proposed his ideas, Charles Lyell and James Hutton help realized that the Earth has also undergone geological changes in the millions of years that it has existed. Their work brought Darwin to the realization that if the Earth could change then life on Earth can change as well.

Before the idea of evolution, Jean-Baptiste Lamark introduced his ideas for the obvious change over time. They included: Tendency toward perfection Use and disuse Inheritance of acquired traits Although, his ideas are incorrect, he paved the way for the work of later biologists studying evolution.

Define the vocabulary in Section 3

Darwin wrote a book called On the Origin of Species Natural variation is simply the variation or differences that are found within a specie Artificial selection in the selective breeding of a particular type of organisms used by farmers and breeders.

Struggle for existence is like the idea of competition, except for in this idea survival or life is a component. Competing for food becomes a struggle for life. Fitness is an individual’s ability to reproduce in a certain area. Adaptation is inherited characteristics that allows an organism to survive (being better suited for the environment.)

Survival of the fittest is the idea that specie are suited for an environment and are able to reproduce and survive. Natural selection is a term used to describe survival of the fittest because this type of selection is not manipulated by man, but by nature.

Descent with modification is the idea that living things have descended through time with changes. Common descent is the principle that all or many species share a common ancestor in which they were derived.

Evidence of Evolution Fossil Record is the term used to refer to all fossils that have been discovered and the information gained from them. Geographic Distribution of Living Species Homologous Structures (Structures that have different functions, but come from the same embryonic tissue) Example are arms of human, bird wings, arms of turtles. Vestigial organs are organs that are homologous, but are extremely reduced in size.

Homologous Structures

Vestigial Organs

Vocabulary Evolution Theory Fossil Natural Selection Struggle for Existence Fitness Adaptation Artificial Selection Vestigial organ Common Descent Homologous structure Darwin Lamarck Descent with modification Lyell Hutton Big Bang Theory Survival of the Fittest Meteor Dinosaur(s)