3. Charles Darwin Proposed a way how evolution works – How did creatures change over time? – by natural selection Collected a lot of evidence to support his ideas – 1809-1882 – British naturalist

4. Charles Darwin English naturalist 1831- Began 5 year voyage on HMS Beagle – Traveled to various places in South America and to the Galapagos IslandsGalapagos Islands – Detailed his observations, took specimens – Concluded that all living things are related VERY CONTROVERSIAL

5. Galapagos Turtles

6. 1859- The Origin of Species Other naturalists were developing the same theory that Darwin did. Even though he was afraid of the Church’s reaction to his book he wanted to get credit for his work.

7. What did Darwin’s Travels reveal The diversity of living species was far greater than anyone had previously known!! These observations led him to develop the theory of evolution by natural selection!!

8. 2006-2007 Insect eaters Bud eater Seed eaters Cactus eater Warbler finch Tree finches Ground finches Darwin & Evolution by Natural Selection

9. Robert Fitzroy Voyage of the HMS Beagle Invited to travel around the world – 1831-1836 (22 years old!) – makes many observations of nature main mission of the Beagle was to chart South American coastline

10. Voyage of the HMS Beagle Stopped in Galapagos Islands – 500 miles off coast of Ecuador

11. Galapagos Recently formed volcanic islands. Most of animals on the Galápagos live nowhere else in world, but they look like species living on South American mainland. 800 km west of Ecuador

12. Many of Darwin ’ s observations made him wonder… Why? Darwin asked: Why were these creatures found only on the Galapagos Islands? Darwin found…many unique species

13. present day Armadillos Darwin found: that creatures have changed over time Evidence that creatures have changed over time ancient Armadillo Darwin asked: Why should extinct armadillos & modern armadillos be found on same continent? Darwin found…clues in the fossils

14. Darwin found: Different shells on tortoises on different islands Darwin asked: Is there a relationship between the environment & what an animal looks like?

15. Finch?Sparrow? Woodpecker? Warbler? Darwin found… birds Finch?Sparrow? Woodpecker? Warbler? Darwin found: Many different birds on the Galapagos Islands. He thought he found very different kinds…

16. Darwin was amazed to find out: All 14 species of birds were finches… Finch?Sparrow? Woodpecker? Warbler? Finch?Sparrow? Woodpecker? Warbler? But Darwin found… a lot of finches Large ground finch Small ground finch Warbler finchTree finch But there is only one species of finch on the mainland! Darwin asked: If the Galapagos finches came from the mainland, why are they so different now?

17. Finch?Sparrow? Woodpecker? Warbler? The finches cinched it! Large ground finch Small ground finch Warbler finchTree finch Big seed eaterSmall seed eater Insect eaterLeaf & bud eater Darwin said: Ahaaaa! A flock of South American finches were stranded on the Galapagos… Darwin found: The differences between species of finches were associated with the different food they ate. different beaks are inherited variations serve as adaptations that help birds compete for food these birds survive & reproduce pass on the genes for those more fit beaks over time nature selected for different species with different beaks

18. Relationship between species (beaks) & food

19. Darwin ’ s finches Darwin ’ s conclusions – variations in beaks differences in beaks in the original flock adaptations to foods available on islands – natural selection for most fit over many generations, the finches were selected for specific beaks & behaviors – offspring inherit successful traits accumulation of winning traits: both beaks & behaviors – separate into different species

20. Warbler finch Woodpecker finch Small insectivorous tree finch Large insectivorous tree finch Vegetarian tree finch Cactus finch Sharp-beaked finch Small ground finch Medium ground finch Large ground finch Insect eaters Bud eater Seed eaters Cactus eater Warbler finch Tree finches Ground finches variation natural selection for best survival & reproduction From 1 species to 14 species…

21. Lamarck - Theory of acquired traits Organisms develop traits during their lifetime and pass on those traits to their offspring

22. Malthus Reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone

23. LaMarck – evolution by acquired traits creatures developed traits during their lifetime give those traits to their offspring – example in reaching higher leaves giraffes stretch their necks & give the acquired longer neck to offspring – not accepted as valid Earlier ideas on Evolution

24. Darwin ’ s view of Evolution Darwin – giraffes that already have long necks survive better – leave more offspring who inherit their long necks variation selection & survival reproduction & inheritance of more fit traits

25. Darwin’s Postulates There is variation among individuals Like begets like (traits are inherited)

26. Postulates cont’d Some individuals are most successful at surviving and reproducing than others Survival and reproductive success are not random – some characteristics enhance probability of success

27. Upshot of Darwin’s Postulates Those characteristics more common in next generations =CHANGE

28. Artificial Selection nature provides variation, humans select variations that are useful. Example - a farmer breeds only his best livestock

29. Natural Selection The traits that help an organism survive in a particular environment are “selected” in natural selection. “Survival of the fittest” Peppered Moth

31. Natural Selection and Species Fitness Overtime, natural selection results in changes in the inherited characteristics of a population. These changes increase a species fitness (survival rate)

32. Evidence for Evolution Homologous Structures Embryology Fossil Record

33. Homologous Structures

34. Embryology

35. Fossil Record