Interest Grabber A Trip Around the World While on his voyage around the world aboard the H.M.S. Beagle, Charles Darwin spent about one month observing life on the Galápagos Islands. There, he encountered some unique animals, such as finches and tortoises. Section On a sheet of paper, list five animals that you have encountered in the past two days. 2. How do these animals differ from the finches and tortoises of the Galápagos Islands? (Examine Figures 15–3 and 15–4 in your textbook.) 3. Propose a hypothesis to account for the differences between the animals that you observed and the finches and tortoises of the Galápagos Islands.

Section Outline 15–1The Puzzle of Life’s Diversity A.Voyage of the Beagle (1831) B.Darwin’s Observations 1.Patterns of Diversity 2.Living Organisms and Fossils 3.The Galápagos Islands C.The Journey Home Section 15-1

Words to Know Evolution – change over time Theory – well-supported testable explanation of natural phenomena Fossils - preserved remains of ancient organisms Hutton and Lyell – this geologic understanding influenced Darwin; recognized that Earth is millions of years old, and the processes that changed Earth in the past are the same processes that operate in the present Principles of Geology – Lyell’s book

Lamarck Jean-Baptiste Lamarck French naturalist Selective use or disuse of organs (1809) Inheritance of acquired traits Theory is incorrect: he did not know that an organism’s behavior has no effect on its inheritable characteristics Book-System of Invertebrate Animals

Thomas Malthus Thomas Malthus (1798) Reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone Proposed that war, famine, and disease limited the growth of human populations

Section 15-1 Figure 15–1 Darwin’s Voyage

Pinta Island Intermediate shell Pinta Isabela Island Dome-shaped shell Hood Island Saddle-backed shell Hood Floreana Santa Fe Santa Cruz James Marchena Fernandina Isabela Tower Giant Tortoises of the Galápagos Islands Section 15-1

Interest Grabber My, How You’ve Changed! Prior to the 1800s, life scientists knew that living things changed over generations. They just didn’t know how these changes were brought about. Section Divide a sheet of paper into two columns and title the first one Inherited Characteristics. Title the second column Acquired Characteristics. In the first column, list the characteristics that you believe you have always had. For example, you may have brown eyes or curly hair. 2. In the second column, list your acquired characteristics. For example, you may have learned how to play a musical instrument. 3. Which of the items in your lists do you think you might pass on to your children? Explain your answer.

Section Outline 15–2Ideas That Shaped Darwin’s Thinking A.An Ancient, Changing Earth 1.Hutton’s Theory of Geological Change 2.Lyell’s Principles of Geology B.Lamarck’s Theory of Evolution 1.Tendency Toward Perfection 2.Use and Disuse 3.Inheritance of Acquired Traits 4.Evaluating Lamarck’s Theory C.Population Growth Section 15-2

Sea level Sedimentary rocks form in horizontal layers. When part of Earth’s crust is compressed, a bend in a rock forms, tilting the rock layers. As the surface erodes due to water, wind, waves, or glaciers, the older rock surface is exposed. New sediment is then deposited above the exposed older rock surface. Movement of Earth’s Crust Section 15-2 Sea level

Figure 15–7 Lamarck’s Theory of Evolution Section 15-2

Interest Grabber When Is a Flipper a Wing? All living things are related. Some relationships are easy to see— your pet cat may not roar like a lion, but it clearly resembles one. Other relationships are less obvious. Section 15-3

Interest Grabber continued 1. On a sheet of paper, construct a table that has five columns and six rows. In the columns, write the following heads: Animal Group, Example, Legs, Fins, and Tail. Then, place the following animal groups in their own row: Mammal, Bird, Fish, Amphibian, Reptile, and Insect. 2. Give one example for each group, and then fill in the information for that example. For Legs, write in the number of legs that each animal has. Do animals with fins have legs? Do animals with wings have legs? If so, how many? 3. Can you tell from your table if a fish is more closely related to a bird or to an amphibian? Explain your answer. Section 15-3

Section Outline 15–3Darwin Presents His Case A.Publication of On the Origin of Species B.Natural Variation and Artificial Selection C.Evolution by Natural Selection 1.The Struggle for Existence 2.Survival of the Fittest 3.Descent With Modification D.Evidence of Evolution 1.The Fossil Record 2.Geographic Distribution of Living Species 3.Homologous Body Structures 4.Similarities in Early Development E.Summary of Darwin’s Theory Section 15-3

Words to know Natural variation – differences among individuals of a species (physical strength, resistance to disease, vision, hearing, etc.) Artificial selection – selection by humans for breeding of useful traits from the natural variation among different organisms (breed largest hogs, fastest horses) Struggle for existence – members of each species compete regularly to obtain food, living space, and other necessities of life Fitness – ability of an individual to survive and reproduce in its specific environment (a result of adaptation)

Adaptation – any inherited characteristic that increases an organism’s chance of survival (sharp quills, behavior in which some animals live and hunt in groups) Survival of the fittest – individuals best suited to their environment survive and reproduce most successfully Natural selection – survival of the fittest; over time, it results in changes in the inherited characteristics of a population (These changes increase a species’ fitness in its environment.) Descent with Modification – each living species has descended, with changes, from other species over time; implies common descent (structures, niches, habitats)

Evidence of Evolution 1.Fossil record (fossils from sequential layers of rock) 2.Geographic distribution of living species – common mainland ancestors 3.Homologous body structures – structures that have different mature forms but develop from the same embryonic tissue; the greater the similarities among homologous structures, the more recently particular species last shared a common ancestor Vestigial structures – traces of homologous structures that do not affect the organism’s ability to survive

4. Similarities in early development (Embryos) In their early stages of development, embryos of chickens, turtles, and rats look similar

Concept Map Section 15-3 includes Evidence of Evolution Physical remains of organisms Common ancestral species Similar genes which is composed ofwhich indicateswhich implies The fossil record Geographic distribution of living species Homologous body structures Similarities in early development

Beaver NORTH AMERICA Muskrat Capybara SOUTH AMERICA Coypu Figure 15–14Geographic Distribution of Living Species Section 15-3 Beaver Muskrat Beaver and Muskrat Coypu Capybara Coypu and Capybara

TurtleAlligatorBirdMammals Typical primitive fish Figure 15–15 Homologous Body Structures Section 15-3

Summary of Darwin’s Theory Struggle for existence Survival of the fittest Descent with modification Natural selection Common ancestry