Unit 5 : Evolution Chapter 15 - Darwin’s Theory of Evolution

Charles Darwin English Born 1809 HMS Beagle Naturalist Very Religious

Darwin’s Observations Animals and plants were well adapted Diverse reproductive strategies Puzzled by location of animals –Rabbits in Argentina, not in Australia Fossils –similar, dissimilar, Extinction

The Beagle’s Journey

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

The Galapagos Islands DesertLarge rainfall Intermediate Shell Domed Shell Saddle backed Shell Climate variation throughout

Tortoises of the Galapagos Saddleback long neck, curved shell, found on Hood Island, desert like Dome Shaped shorter neck, domed shell, lush vegetation, covers the ground, Isabela island

Many different varieties in different locations Finches

Journey Home Animals and plants varied a great deal from island to island Did the organisms on different islands belong to the same species? Was the ancestor from S. America?

Influences on Darwin Fossil Record

James Hutton Earth - millions of years old, not 5700

Charles Lyell Past events are explained by the processes that scientists can see today.

Jean-Baptiste Lamarck Proposes 1st theory of evolution –use vs. disuse –acquired traits are passed on –leads to changes in species

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

Thomas Malthus Economist - unchecked population growth leads to a lack of space and food Frog Eggs - What detemines survival?

Artificial Selection Farmers and breeders –Selective Breeding

Darwin’s View - On the Origin of the Species Darwin: Reluctant Rebel

Natural Variation passed on to future generations

Struggle for Existence

Fitness Ability to survive and reproduce successfully

Adaptations - physical characteristics or behaviors Camouflage

Survival of the Fittest - (Natural Selection) Individuals that are best suited for their environment have high levels of fitness and therefore survive and reproduce

Descent with Modification Species change overtime All organisms share a common ancestor (common descent)

Darwin’s Evidence of Evolution Fossil Record Distribution of Living Species Homologous Body Structures Embryo Development

Fossil Record Evidence of change over time Age of the Earth

Distribution of Living Species - I Unrelated organisms look similar because of common ecological conditions - Convergent Evolution

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

Distribution of Living Species - II Finches - all share a common mainland ancestor, differences are due to the environment

Homologous Structures - same basic design, modifications

Vestigial Organs - traces of homologous structures

Embryo Development Embryonic Cells develop in the same group and similar patterns

Reviewing Darwin’s Theory Variation Large amounts of offspring Competition Struggle for Existence Survival of the Fittest Descent with Modification via Natural Selection Common Descent How does evolution really work?evolution really work?