Chapter 15 Darwin’s Theory of Evolution 15-1The puzzle of Life’s Diversity 15-2Ideas That Shaped Darwin’s Thinking 15-3Darwin Presents His Case

15-1The Puzzle of Life’s Diversity Objectives What was Charles Darwin’s contribution to science? What pattern did Darwin observe among organisms of the Galapagos Islands?

Introduction Biological diversity: variety of living things Evolution: (change over time) the process by which modern organisms have descended from ancient organisms Scientific theory: a well-supported testable explanation of phenomena that have occurred in the natural world

Voyage of the Beagle Charles Darwin was the naturalist on board the H.M.S. Beagle in 1831 Made many observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time Has become the theory of evolution

Darwin’s Observations Darwin observed and recorded many different species of organisms each time the Beagle docked

Patterns of Diversity Darwin noticed many plants and animals were equipped to survive in certain environments He questioned why organisms lived in one area but not another

Living Organisms and Fossils Fossils: preserved remains of ancient organisms Some fossils resembled organisms that were still alive

The Galapagos Islands Close together Different climates Lowest islands Hot, dry, little vegetation Higher islands More rainfall, variety of plants and animals, lots of vegetation

The Galapagos Islands Cont’d Organisms varied from island to island Iguanas Land tortoises

Blue Ticket Question How did the fossils Darwin observed compare with the living organisms he studied?

Blue Ticket Answer Some of the fossils resembled organisms that were still alive

The Galapagos Islands Cont’d Collected several types of small, ordinary-looking brown birds hopping around Different shaped beaks

The Journey Home Darwin observed that the characteristics of many animals and plants varied noticeable among the different islands of the Galapagos. He wondered if these organisms had a common ancestor and evolved differently after being isolated from each other

15-1 Exit Ticket