1. Darwin’s Theory of Evolution Chapter 10

2. The Puzzle of Life’s Diversity Charles Darwin – THEORY OF EVOLUTION BY MEANS OF NATURAL SELECTION Made observations and devised a theory on how life changes over time

3. Voyage of the HMS Beagle Galapagos Islands and Beyond

4. Darwin was influenced by several other scientists: -James Hutton and Charles Lyell – Studied rock formations and changes in the earth -Alfred Wegner - began theory of coined term “Pangaea continental drift; coined term “Pangaea” -Jean Baptiste de Lamarck – Theory of Inheritance of Acquired Characteristics

5. Darwin’s Observations a)Patterns of Diversity were shown b)Unique Adaptations in organisms c)Species Not Evenly Distributed i.Australia, Kangaroos, but No Rabbits ii.S. America, Llamas

6. Darwin’s Observations Both Living Organisms & Fossils collected Fossils included: Trilobites Giant Ground Sloth of South America This species NO longer existed. What had happened to them?

7. Vocab Extinct species = a species is no longer living on this earth –EX: the Dodo Bird Extant species = a species that is currently living and reproducing on earth

8. Definition Evolution is the slow, gradual change in a population of organisms over time

9. Darwin’s Observations Left unchecked, the number of organisms of each species will increase exponentially (overproduction In nature, populations tend to remain stable in size Environmental resources are limited (competition) Only the best-suited organisms survive (survival of the fittest)

10. LIMITING FACTORS keep populations in check Food or water Competition for mates Space (spreads disease) Presence or absence of antibiotics Change in temperature/ climate

11. Darwin’s Conclusion Production of more individuals than can be supported by the environment leads to a struggle for existence among individuals Only a fraction of offspring survive each generation Survival of the Fittest

12. Darwin’s Big Ideas Overproduction –More offspring are produced than can survive Competition –Resources are limited; competition ensues Survival of the Fittest –Only the individuals best suited for their environment will survive and reproduce

13. Darwin’s Observations Individuals of a population vary extensively in their characteristics with no two individuals being exactly alike. Much of this variation between individuals is inheritable.

14. Darwin’s Conclusion Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals Called Natural Selection Acts on phenotype

15. The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection)The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection) New species evolve (SPECIATION)New species evolve (SPECIATION) Darwin’s Theory of Evolution

16. Natural Selection 1.Individuals vary within a species 2.Individuals compete for resources in the struggle for existence 3.Fitness is the ability of an individual to survive and reproduce in its environment

17. Natural Selection cont. 4.Fitness is the result of adaptations 5.Adaptations are inherited characteristics or traits that increase an organisms ability to survive (or increase fitness) 6.Adaptations can be physical OR behavioral 7.Individuals that are most fit are able to survive and reproduce - “survival of the fittest.”

18. Natural Selection cont. 8.Natural Selection – results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in its environment

19. Over Time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in its environment.

20. How Evolution Works

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

22. Artificial Selection: Roses

23. III. Descent with Modification Each living species has descended with changes from other species over time

24. IV. Evidence of Evolution 1.Fossil Record 2.Biogeography (Geographic Distribution of Living Species) 3.Anatomical Homologies (Similar Body Structures) 4.Developmental Homologies (Similarities in Embryology) 5.Molecular Homologies (Similarities in DNA sequences)

25. Evidence of Evolution A. Fossil Record Fossils are preserved remains of ancient organisms By comparing fossils from older rocks with fossils from younger layers, could see life on Earth has changed over time. Darwin view the fossil record as a record of evolution while others in his time only viewed them as preserved remains.

26. Evidence of Evolution B. Biogeography: Geographic Distribution of Living Species –Different environments contain similar organisms with distinct differences. Ex. Flying squirrel (N. America) and sugar glider (Australia) –Alfred Wallace

27. Evidence of Evolution C. Homologous Body structures –Structures that have different mature forms but develop from the same embryonic tissues e.g. Wing of bat, human arm, leg of turtle –vestigial organs – traces of homologous organs from other species having no apparent function e.g. Appendix (digest cellulose), pelvic girdle in whales –recapitulation- structures lost during development e.g. Gill slits Turtle Alligat or Bird Mammal Ancient lobe- finned fish http://cas.bellarmine.edu/tietjen/Ec&Ev_Distance_learning/Evidence/evidence_pix.htm

28. Ontogeny recapitulates phylogeny ontogeny is the process of embryo development (from the Greek onto, meaning "being" or "existence" and genesis meaning "origin") phylogeny is a species' evolutionary history (from the Greek phyla, meaning "tribe" and genesis meaning "origin")

29. Homologous Structures

30. Evidence of Evolution D. Developmental Homologies: Similarities in Embryology –In their early stages of development, chickens, turtles and rats look similar, providing evidence that they shared a common ancestry.

31. Evidence for Evolution - Comparative Embryology Similarities In Embryonic Development

32. E. Molecular Homologies: Similar DNA sequences Organisms in the same taxonomic categories share similar DNA sequences and proteins.

33. Patterns of Evolution Charles Darwin understood that evolution was a slow and gradual process. Still, if evolution is gradual, there should be a fossilized record of small, incremental changes on the way to a new species. His conclusion was that the fossil record lacked these transitional stages because it was incomplete. In 1972, evolutionary scientists Stephen Jay Gould and Niles Eldredge proposed another explanation, which they called "punctuated equilibrium."

34. Gradualism and Punctuated Stephen Jay Gould and Niles Eldredge

35. Summary of Darwin’s Theory: Evolution by Natural Selection –Variations occur within populations, and some of the variations are favorable. –More offspring are produced than can possibly survive –Organisms compete for resources and individuals with favorable variations are more likely to survive. –Natural Selection causes species to changes over time. –Species alive today are descended with modification from ancestors Survival of the Fittest!