1. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 10 Principles of Evolution

2. Overview: Endless Forms Most Beautiful A new era of biology began in 1859 when Charles Darwin published The Origin of Species The Origin of Species focused biologists’ attention on the great diversity of organisms Darwin noted that current species are descendants of ancestral species Evolution can be defined by Darwin’s phrase descent with modification Evolution can be viewed as both a pattern and a process Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

3. Darwin’s Two Major Points from Origin of Species 1.Presented evidence that many species of organisms presently inhabiting the Earth are descendents of ancestral species (common descent) 2.Proposed a mechanism for the evolutionary process (natural selection)  a population’s allele frequency can change over generations if individuals that possess certain heritable traits leave more offspring than others  results in evolutionary adaptation – accumulation of inherited characteristics that enhance organisms’ ability to survive and reproduce in specific environments  evolution – change over time in genetic composition of a population and could eventually lead to new species Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

4. Fig. 22-1

5. The Historical Context of Darwin’s Life and Ideas

6. Lamarck’s Hypothesis of Evolution Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

7. Fig. 22-4

8. Fig. 22-5 NORTH AMERICA EUROPE AFRICA AUSTRALIA GREAT BRITAIN SOUTH AMERICA ATLANTIC OCEAN PACIFIC OCEAN Cape of Good Hope Tierra del Fuego Cape Horn Tasmania New Zealand Andes Equator The Galápagos Islands Pinta Marchena Genovesa Santiago Daphne Islands Pinzón Fernandina Isabela San Cristobal Santa Fe Santa Cruz Florenza Española

9. Darwin’s Focus on Adaptation In reassessing his observations, Darwin perceived adaptation to the environment and the origin of new species as closely related processes: – An adaptation is a genetic variation that is favored by selection and is manifested as a trait that provides an advantage to an organism in a particular environment. – Any heritable trait that increases an organism’s reproductive capability as compared to those without the trait. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

10. Galapagos Finches

11. The Origin of Species In 1844, Darwin wrote an essay on the origin of species and natural selection but did not introduce his theory publicly, anticipating an uproar In June 1858, Darwin received a manuscript from Alfred Russell Wallace, who had developed a theory of natural selection similar to Darwin’s Darwin quickly finished The Origin of Species and published it the next year In his manuscript, Darwin developed two main ideas: – Descent with modification explains life’s unity and diversity – Natural selection is a cause of adaptive evolution Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

12. Fig. 22-9 Kale Kohlrabi Brussels sprouts Leaves Stem Wild mustard Flowers and stems Broccoli Cauliflower Flower clusters Cabbage Terminal bud Lateral buds

13. Fig. 22-10

14. Fig. 22-11 Spore cloud

15. Inference #1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals Inference #2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Darwin’s Big Ideas – The Inferences

16. Fig. 22-UN1 Observations Over time, favorable traits accumulate in the population. Inferences and Individuals in a population vary in their heritable characteristics. Organisms produce more offspring than the environment can support. Individuals that are well suited to their environment tend to leave more offspring than other individuals

17. Darwin was influenced by Thomas Malthus who noted the potential for human population to increase faster than food supplies and other resources If some heritable traits are advantageous, these will accumulate in the population, and this will increase the frequency of individuals with adaptations This process explains the match between organisms and their environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Competition for Resources

18. Natural Selection: A Summary Individuals with certain heritable characteristics survive and reproduce at a higher rate than other individuals Natural selection increases the adaptation of organisms to their environment over time If an environment changes over time, natural selection may result in adaptation to these new conditions and may give rise to new species Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

19. Natural Selection: A Summary Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings FITNESS is measured as REPRODUCTIVE success. Natural selection is differential success in reproduction - it results from the interaction between individuals that vary in heritable traits and their environment.

20. Fig. 22-12 (b) A stick mantid in Africa (a) A flower mantid in Malaysia

21. Natural Selection: A Summary 1.Overpopulation - more organisms are born than can survive 2.Variation within a population - there will be many variation for different traits among individuals 3.Competition within the population - individuals will compete for survival: food, mates, shelter, etc. 4.Survival of the Fittest - those with traits best suited to the environment will be more likely to survive 5.Reproduction - individuals that survive will pass their traits on to the next generation Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

22. Key Points to Remember 1.Population - group of interbreeding individuals belonging to a particular species and sharing a common geographic area 2.A population is the smallest unit that can evolve 3.Natural selection occurs because of interaction between organisms and their environments 4.Natural selection works to increase or decrease the occurrence of heritable traits 5.Individuals are selected, but populations evolve Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

23. Key Points to Remember 1.Theory - an accepted hypothesis that has been tested over and over again without yet being disproved 2.Definition - Evolution is the change in the overall genetic makeup (allele frequency) of a population over time 3.Three Basic Components a. Individuals cannot evolve. Populations evolve. b. Natural selection is the mechanism of evolution. c. Evolution occurs by chance (NOT GOAL ORIENTED). Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

24. Natural selection does not create new traits, but edits or selects for traits already present in the population The local environment determines which traits will be selected for or selected against in any specific population Because environments change, they act as selective mechanisms on populations – Example: peppered moth Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Evolution and the Environment

25. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Evolution and the Environment Peppered Moth

26. Evidence for Evolution Evolution is supported by an overwhelming amount of scientific evidence New discoveries continue to fill the gaps identified by Darwin in The Origin of Species Three examples provide direct evidence for natural selection: 1.the evolution of insecticide resistance; 2.and the evolution of drug-resistant HIV Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

27. Evolution of Insecticide Resistance Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 1.By spraying crops with poisons to kill insects, humans have unwittingly favored the reproductive success of insects with inherent resistance to poisons. 2.Resistant individuals survive and reproduce, passing the gene for resistance to offspring. 3.Additional applications of the same insecticide will be less effective, and the frequency of resistant insects in the population will grow.

28. The Evolution of Drug-Resistant HIV The use of drugs to combat HIV selects for viruses resistant to these drugs HIV uses the enzyme reverse transcriptase to make a DNA version of its own RNA genome The drug 3TC is designed to interfere and cause errors in the manufacture of DNA from the virus Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

29. Fig. 22-14 Weeks Patient No. 3 Patient No. 2 Patient No. 1 Percent of HIV resistant to 3TC 0 0 25 50 75 100 2 4681012

30. Evidence for Evolution Evidence that the diversity of life is a product of evolution pervades every research field of biology. – Fossil Record Evidence – Succession of Fossil Forms – Comparative Anatomy – Anatomical Homologies – Embryological Homologies – Molecular Homologies – Biogeography – Geographic Distribution of Species – Continental Drift Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

31. Evidence for Evolution Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

32. How Rocks and Fossils Are Dated Sedimentary strata reveal the relative ages of fossils: – In relative dating, the order of rock strata is used to determine the relative age of fossils. Older specimens are found in deeper layers of strata. The absolute ages of fossils can be determined by radiometric dating – Radiometiric dating uses the decay of radioactive isotopes to determine the age of the rocks or fossils. – It is based on the rate of decay, or half-life of the isotope (the time required for half the parent isotope to decay).

33. Fig. 22-17 Humerus Radius Ulna Carpals Metacarpals Phalanges HumanWhale Cat Bat Homology Homologous structures are those found in different species that are similar and result from common ancestry.

34. Fig. 22-18 Human embryoChick embryo (LM) Pharyngeal pouches Post-anal tail Comparative Embryology

35. The skeletons of some snakes retain vestiges of the pelvis and leg bones of walking ancestors. We would not expect to see these structures if snakes had an origin separate from other vertebrate animals. Vestigial Structures

36. Molecular Homologies Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

37. Convergent Evolution Although organisms that are closely related share characteristics because of common descent, distantly related organisms can resemble one another for a different reason: – Convergent evolution is the evolution of similar, or analogous, features in distantly related groups. – Analogous traits arise when groups independently adapt to similar environments in similar ways. – Convergent evolution does not provide information about ancestry! Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

38. Homologous v. Analogous Structures Homologous structures are similar structures occurring in different species that are believed to be derived from a common ancestor. Analogous structures are similar structures occurring in different species that are believed to be the result of convergent evolution (similar environmental pressures). Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

39. Fig. 22-20 Sugar glider Flying squirrel AUSTRALIA NORTH AMERICA

40. Biogeography Darwin’s observations of biogeography, the geographic distribution of species, formed an important part of his theory of evolution – Islands have many endemic species that are often closely related to species on the nearest mainland or island – Earth’s continents were formerly united in a single large continent called Pangaea, but have since separated by continental drift – An understanding of continent movement and modern distribution of species allows us to predict when and where different groups evolved Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

41. The Geographic Distribution of Species Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

42. Continental Drift Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

43. Endemic Species Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

44. Populations of Organisms Continue to Evolve Scientific evidence supports the idea that evolution has occurred in all species. Scientific evidence supports the idea that evolution continues to occur: – Chemical Resistance: mutations for resistance to antibiotics, pesticides, herbicides or chemotherapy drugs occur in the absence of the chemical. – Emergent Diseases: mutations that allow diseases to expand their host range. – Observed Directional Phenotypic Changes: Grant’s observations of Darwin’s finches in the Galapagos. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

45. Summary of Darwin’s Theory http://bcs.whfreeman.com/thelifewire/content/chp23/2302003.html http://bcs.whfreeman.com/thelifewire/content/chp23/2302003.html 1.Individual organisms in nature differ from one another and some of this variation is inherited 2.Organisms in nature produce more offspring than can survive – and many that survive do not reproduce 3.Members of each species must compete for resources 4.Individuals best suited to their environment survive and reproduce most successfully – they pass their traits onto their offspring 5.Species change over time – this is caused by natural selection – new species arise and other species disappear 6.Species alive today have descended with modifications from species that lived in the past 7.All organisms on Earth are united into a single tree of life by common descent Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings