What is Evolution? – The Process of Evolution

1. What is Evolution? – The Process of Evolution Biological populations Groups of individuals of the same species that are subdivided from other populations by geography Biological evolution Change in the characteristics of a population of organisms that occurs of over the course of generations. Evolutionary changes are inherited via genes.

2. What is Evolution? – The Process of Evolution Pesticide resistant lice are an example of biological evolution.

3. What is Evolution? - The Process of Evolution • Populations evolve, NOT individuals. • In the lice example, the genetic structure of the population of lice changed. • Individuals without a gene for resistance died • Over time, the population changed to mostly resistant individuals

4. What is Evolution? – The Process of Evolution Natural selection – the differential survival and reproduction of individuals in a population Process by which populations adapt to varying environments Examples: Pesticide resistance in crop-eating insects Antibiotic resistance in infectious bacteria

5. What is Evolution? – The Process of Evolution Microevolution – changes that occur within a species and the characteristics of a population. Easily observed, relatively non-controversial. Macroevolution – changes that occur, as a result of microevolution, over long periods of time and result in the origin of new species. Controversial among non-biologists.

6. What is Evolution? – The Theory of Evolution Ambiguity of the word “theory” Everyday usage: theory = best guess, or tentative explanation Scientific usage: theory = body of accepted general principles, supported by many lines of evidence. Examples: atomic theory, gravity, germ theory.

7. What is Evolution? – The Theory of Evolution Theory of evolution All species present on earth today are descendents of a single common ancestor, and all species represent the product of millions of years of accumulated evolutionary changes.

8. What is Evolution? – The Theory of Evolution Theory of common descent

9. Animation: Principles of Evolution Click “Go to Animation” / Click “Play”

10. BioFlix: Mechanisms of Evolution

11. Charles Darwin and the Theory of Evolution Theory of Evolution is sometimes called “Darwinism” because Charles Darwin is largely credited with introducing the concept to mainstream science. Many philosophers of science before Darwin had notions of organisms changing over time. Anaximander – Greek philosopher who suggested that humans evolved from fish that had moved onto land Lamarck – published ideas about inheritance of acquired traits in 1809

12. Charles Darwin and the Theory of Evolution - The Voyage of the Beagle At age 22, Darwin set sail as ship’s naturalist aboard the HMS Beagle on a five year long trip. Darwin’s job was to collect and observe “anything worthy to be noted for natural history.” Darwin had a book by Lyell, Principles of Geology, which postulated earth was old and changes occurred over long periods of time.

13. Charles Darwin and the Theory of Evolution - The Voyage of the Beagle The following had influences on Darwin during the voyage: Rainforests of Brazil Fossils that he collected Birds and reptiles of the Galapagos Islands

14. Charles Darwin and the Theory of Evolution - The Voyage of the Beagle

15. Charles Darwin and the Theory of Evolution - Developing the Hypothesis of Common Descent Darwin returned to England in 1836, but did not publish his ideas immediately. Spent about 20 years refining his ideas Learned about animal husbandry (selective breeding) Finally published On the Origin of Species in 1858

16. Examining the Evidence for Common Descent Several lines of biological evidence point to a common ancestor: Biological classification Anatomical similarities between organisms Useless traits in modern species Shared developmental pathways DNA similarities Distribution of organisms on earth (biogeography) Fossil evidence

17. Examining the Evidence for Common Descent Biological classification implies common ancestry. Linnaean Classification Gives each species a two-part or binomial name in Latin Carolus Linnaeus groups organisms in a hierarchy going from broadest to narrowest groupings

18. Examining the Evidence for Common Descent

19. Examining the Evidence for Common Descent Anatomical homology Mammalian forelimbs have the same set of bones. The underlying structure is similar despite the very different functions.

20. Examining the Evidence for Common Descent Useless traits in modern species Vestigial traits are traits that function in one organism but are greatly reduced in others For example: Ostrich and penguins form wings but do not fly because the wings are non-functional Humans have a tailbone by have no tail

21. Examining the Evidence for Common Descent –Developmental Homologies A consequence of shared developmental pathways is similarity among chordate embryos

22. Examining the Evidence for Common Descent – Molecular Homology DNA similarities: Birds in same genus have DNA that is more similar to one another, while distantly-classified birds have DNA that is less similar. Molecular clock allows the use of DNA sequence differences between species to determine when they diverged from their common ancestor. Ruddy turnstone Ruddy turnstone Black turnstone Red knot Caspian tern 100% 90% 82% 72% % DNA similarityto Ruddy turnstone Same genus(Arenaria) Same family(Scolopacidae) Same order(Charadriiformes)

23. Examining the Evidence for Common Descent – Biogeography Biogeography is the distribution of species on earth. Different species of mockingbird found on Galapagos all resemble another species found on the mainland.

24. Examining the Evidence for Common Descent –The Fossil Record Fossils are remains of living organisms left in soil or rock. Horse fossils provide a good sequence of evolutionary change within a lineage.

25. Examining the Evidence for Common Descent – The Fossil Record Fossilization is the formation of fossils

26. Examining the Evidence for Common Descent –Fossil Record Bipedal humans have some unique anatomical traits, such as features of hips, knees, and skull. Anatomical differences between humans and chimpanzees allow for identification of fossils

27. Examining the Evidence for Common Descent –Radiometric Dating Radiometric dating Used to determine age of rocks Relies on decay of radioactive isotopes into daughter products The rate of decay is measured by the element’s half-life

28. Examining the Evidence for Common Descent –Radiometric Dating Using radiometric dating, scientists have estimated the age of fossil hominims.

29. Examining the Evidence for Common Descent – Radiometric Dating Trends in human evolution Larger brains, Flatter face, Reduced jaw size

30. Are Alternatives to the Theory of Evolution Equally Valid? – The Origin of Life The origin of life Evolution is the study of how life changes. It doesn’t really address issue of how life began. Experiment evidence does give some clues about beginnings of life.

31. Gases (CH4, NH3,H2O, H2) Electrodes Energy applied in theform of heat andelectrical charges Condenser Watervapor Organic moleculescollected from thesystem 3 1 2 Water droplets Inorganic molecules,including water andmethane, added tosystem Water Heat Are Alternatives to the Theory of Evolution Equally Valid? - The Origin of Life • The Miller-Urey experiment demonstrated that complex molecules can spontaneously form from simple chemicals. Figure 9.29

32. Evolutionary theory informs all aspects of modern biology. Evolutionary theory helps us understand the function of human genes. Evolutionary theory is important to understanding species interactions. Evolutionary theory is important for predicting the biological consequences of climate change.

33. The head lice that have become resistant to the pesticide permethrin demonstrate microevolution. True or False: The individual head lice have evolved. • True. • False.

34. Which of the following do not belong in the order Primates. • Monkeys • Humans • Apes • All of the above belong to the order Primates

35. Which of the following is an example of a vestigial trait? • A human tailbone • A dolphin’s blowhole • A gorilla’s opposable thumb • A penguin’s flippers

36. Where did humans evolve? • North America • Europe • Africa • Galapagos Islands

37. True or False: Stanley Miller attempted to recreate conditions on early Earth. After one week, he found that complex organic molecules had formed spontaneously. • True. • False.

38. What is shown by the y-axis of this graph? • Percentage of parent element remaining • Time (in millions of years) • Depth of burial • Number of fossils found