1. Evolution

2. Evolution Process by which modern organisms have descended from ancient organisms

3. Voyage of the Beagle Charles Darwin set sail around the world While on his journey, he made many observations and collected evidence that led him to propose a hypothesis about the way life changes over time His ideas are now a theory

4. Voyage of the Beagle Darwin collected specimen of plants and animals He observed that plants and animals were well adapted to the environment they were in He was puzzled by where different species did and did not live

5. Voyage of the Beagle Also on his journey, Darwin picked up fossils he found At one point on his trip, he visited the Galapagos Islands which is west of South America All the islands there had different climates and the turtles there differed by their shells

6. 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

7. Voyage of the Beagle Darwin also found tons of birds on the islands that varied in their beaks Overall he found that the characteristics of many plants and animals varied among the different islands He wondered if the species on the different islands had once been members of the same species from an original South American ancestor species

8. Ideas Behind Darwin’s Thinking In Darwin’s day, people believed that forms of life had been created only a few thousand years ago. They also believed that the planet and living things had not changed at all over time. A fossil record began changing people’s minds!

9. Ideas Behind Darwin’s Thinking Scientists helped to show that Earth is many millions of years old and the processes that changed earth in the years past are the same processes that operate in the present. Hutton (1785) – says that the earth is shaped by geological forces that took place over very long periods of time. The earth is millions of years old!

10. 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

11. Ideas Behind Darwin’s Thinking Malthus (1798) – he reasoned that if the human population continued to grow unchecked, sooner or later, there would be insufficient living space and food for everyone Lamarck – ◦ He said that living things have changed over time and that all species were descended from other species ◦ He also realized the organisms have adapted to their environment

12. Ideas Behind Darwin’s Thinking ◦ Lamarck’s ideas were being shared in 1809 (the year Darwin was born) 1.Tendency toward perfection – all organisms have a tendency to strive complexity and perfection  Organisms are constantly changing and acquiring new features to make them more successful 2.Use and disuse of organs –  Organisms acquired or lost certain traits during their lifetime  These new traits could be passed on to their offspring  This process led to changes in species

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

14. Ideas Behind Darwin’s Thinking The only thing Lamarck was really right about was that organisms are adapted to their environment. Lyell (1833) – “Principles of Geology” – the processes occurring now have shaped earth’s geological features over long periods of time.

15. Darwin’s Origin of Species The birds found on Galapagos Islands belonged to three different species found no where else in the world He found that all the islands species were different from the mainland species Darwin only published his work after he saw that Wallace’s ideas were similar to his.

16. Darwin’s Origin of Species In his work, he described the ideas behind natural selection He said that variation mattered In artificial selection, nature provided the variation and humans selected those variations that they found useful At this time, no one knew about genetics!

17. Natural Selection The struggle for existence Members of each species compete regularly to obtain food, living space and other necessities of life (predator versus prey) Everything centered on the idea of Survival of the Fittest

18. Natural Selection Survival of the Fittest ◦ All depends on how well suited an organism is to its environment ◦ Fitness – the ability of an individual to survive and reproduce in its environment ◦ Adaptations - any inherited characteristic that increases an organism’s chance of survival ◦ A successful adaptation enables organisms to become better suited to their environment and better suited to survive and reproduce

19. Natural Selection Survival of the Fittest cont’d ◦ Survival of the fittest – individuals that are better suited to their environment survive and reproduce most successfully ◦ Natural selection allows for survival of the fittest because only certain individuals in a population produce new individuals ◦ Over time, natural selection results in changes in the inherited characteristics of a population. ◦ These changes increase a species' fitness in its environment

20. Natural Selection Descent with modification ◦ Each living species has descended with changes from other species over time ◦ All living organisms are related to one another (a common decsent)

21. Concept Map 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

22. Evidence of Evolution Darwin said living things have been evolving on Earth for millions of years Evidence – 1. Fossil record ◦ Fossils – the record of the history of life ◦ Compare fossils from older rock layers to those in younger rock layers ◦ Also found in transitional fossils

23. Evidence of Evolution 2. Geographic Distribution of Living Species ◦ Species living on different continents had each descended from different ancestors ◦ Since some animals on each continent were living under similar ecological conditions, they were exposed to similar pressures of natural selection ◦ So different animals end up evolving features in common

24. 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

25. Evidence of Evolution 3. Homologous Body Structure ◦ He found anatomical similarities among the body parts of animals with backbones ◦ Ex – arms, wings, legs and flippers ◦ All differ from the function they perform but they are all from the same basic bones ◦ Limbs have adapted in ways for organisms to survive

26. TurtleAlligatorBirdMammal Ancient lobe-finned fish Figure 15– 15 Homologous Body Structures

27. Evidence of Evolution ◦ Homologous structure – structures that have different mature forms but develop from the same embryonic tissues  This is evidence that all 4-limbed vertebrates have descended from common ancestors ◦ Vestigial organs – homologous structures that serve no important function  They are not eliminated by natural selection because they don’t affect an organism’s ability to survive and reproduce

28. Evidence of Evolution 4. Similarities in embryology ◦ Embryonic stages are similar ◦ They look similar in early stages of development ◦ There are common cells and tissues that grow in similar ways

29. Anatomy and Embryology

33. Summary of Darwin’s Theory 1. Individual organisms differ and some of this variation is heritable (can be passed on). 2. Organisms produce more offspring that can survive and many that do survive do not reproduce 3. Organisms compete for limited resources

34. Summary of Darwin’s Theory 4. Each unique organism has different advantages and disadvantages in the struggle for existence. ◦ Individuals best suited reproduce most successfully. ◦ They pass on their heritable traits. ◦ Others die or leave less offspring. ◦ SO species will change over time.

35. Summary of Darwin’s Theory 5. Species alive today are modifications from ancestral species that lived in the past. ◦ ALL ORGANISMS ARE UNITED!!!!