1. Darwin’s Observations and Theory of Evolution

2. After Cambridge, Charles was recommended for a surveying trip on the HMS Beagle. Darwin sailed around the world on the Beagle for 5 years, working as a naturalist.

3. Remember, Evolution Is Cumulative change in heritable characteristics of a population Change in genetic frequencies over time Change with inheritance From http://evolution.berkeley.edu/evosite/evo101/IIntro.shtml

4. The Galapagos Islands 500 miles west of Ecuador in the Pacific Ocean, directly on the equatorVolcanic islands off the coast of South America, 500 miles west of Ecuador in the Pacific Ocean, directly on the equator Island species varied from mainland species & from island-to-island species Each island had long or short neck tortoises

6. The Galapagos Islands Finches on the islands resembled a mainland finch More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) Finches had different types of beaks adapted to their type of food gathering

8. Darwin wondered if the birds and other animals had been created to match their environment, why didn’t these birds look like the birds of the African continent, since the environments of both the Galapagos and Africa were similar.

9. Darwin guessed that some of the birds from South America migrated to the Galapagos. Once on the islands, the birds must have changed over the years.

10. This would explain the numerous species of birds present. woodpecker finch cactus finch large ground finch

11. Darwin’s Observations Patterns of Diversity were shown Unique Adaptations in organisms Species Not Evenly Distributed Australia, Kangaroos, but No Rabbits S. America, Llamas

12. Darwin’s Observations Patterns in the species suggested that the species had changed over time and had given rise to new and different species. Both Living Organisms & Fossils collected Fossils included: Trilobites Giant Ground Sloth of South America This species NO longer existed. What had happened to them?

13. Darwin called this… or over time the slow, gradual change in a species population over time Darwin concluded: Each species has descended, with changes, from other species over time. Descent With Modifications

14. Common Descent with Modification Darwin proposed that organisms descended from common ancestors Idea that organisms change with time, diverging from a common form Caused evolution of new species

15. Descent With Modification Takes Place Over Long Periods of Time Natural Selection Can Be Observed As Changes In –Body Structures –Ecological Niches –Habitats

16. Descent With Modification Species Today Look Different From Their Ancestors Each Living Species Has –Descended –With Changes –From Other Species –Over Time

17. Darwin extended these principles to biology, which helped him form his theory of… …or Survival of the Fittest.

18. Natural selection was the mechanism by which Darwin proposed that evolution took place. Darwin published his theory in the book

19. Natural Selection Driving force for evolution During the struggle for resources, strongest survive & reproduce Idea that at least some of the differences between individuals, which impact their survival and fertility, are inheritable

20. Five basic components of

21. 1. All species have genetic variation. Every species is different, even within itself. Look around you…are you all the same?

22. 2. Organisms produce more offspring than can survive. Many that survive do not produce offspring. The female green sea turtle lays a clutch of about 110 eggs. She may lay several clutches. It is likely that less than 1% of the hatchlings will ever reach sexual maturity.

23. 3. Since more organisms are produced than can survive, there is competition (struggle for existence). Competition exists WITHIN and AMONG species. food Within and Among Species for And Within a Species for water mates shelterspace

24. The constant struggle for survival is affected by short-term natural disasters. (drought, fires, floods, snowstorms, hurricanes, and tornadoes) The constant struggle for survival is also affected by long-term changes in the environment. (ice ages, biome shifts, etc)

25. 4. Survival of the fittest Some organisms are more suited to their environment as a result of variations in the species. the ability of an individual to survive and reproduce in its specific environment. Fitness is a result of adaptations. Fitness: the ability of an individual to survive and reproduce in its specific environment. Fitness is a result of adaptations. He who spreads the most genes wins! 1st Individuals that are fit to their environment survive and leave more offspring than those who aren’t.

26. The result? Organisms with favorable traits are more fit, thus they leave behind more offspring than those who are less fit.

27. 5. Descent with modification: Living species today are descended with modifications from common ancestral species that lived in the past. Over time, genes for less favored characteristics will be eliminated from the gene pool. Example: giraffes and their increasingly longer necks. Characteristics of fit individuals increase in a population over time.

28. Natural Selection: Survival of the Fittest the variation exists first. An adaptation is any inherited characteristic (a genetic variation) that can increase an organism’s chance of survival. the environment changes. a variation may give an advantage to survive environmental change. An organism does not change because of need or desire to survive. The organism either already has the variation that enables it to survive or it dies.

29. The result? These favorable traits persist in the population and will become more frequent.

30. As the environment changes, organisms must have variations that allow them to survive (adapt) to those changes or die. If an entire population of a species cannot adapt, that species becomes extinct, or dies out.

31. In sum… Differential reproductive success leads to change in favorable traits among generations

32. In sum… Natural selection occurs as a result of interactions between the environment and the genetic variability demonstrated in living organisms. It is the result of differential reproductive success.

33. It is estimated that 1/5 or more of the world’s species will become extinct if the rainforests are destroyed. Many scientists say that the earth is currently experiencing a mass extinction crisis.

34. If we are in a period of mass extinction... What animals will your grandchildren be able to see in the wild? Visit the World Wildlife Fund website for more information on endangered species. Photos by MartinHarvey World Wildlife Fund International