Chapter 22 Descent with Modification

1. James Hutton 1795 A Darwinian View of Life Chapter 22Descent with Modification Thomas Malthus 1798 Charles Darwin 1859 Charles Lyell 1830 Jean-Baptiste Lamarck 1809 Alfred Wallace 1858

2. Descent with Modification Theme • Evolutionary change is based on the interactions between populations & their environment which selects individuals who possess traits that increase fitness, resulting in adaptations (inherited characteristics) that increase in frequency over time • Evolution = change over time in the genetic composition of a population

3. A. Thoughts About Earth Before Darwin • Plato: function of organisms designed to achieve ultimate goodness and harmony imposed by an external creator. • Aristotle: species do not change; are arranged on scale in increasing complexity or scalanatura“scale of nature” of perfectionism Aristotle 384-322 B.C. Plato427-347 B.C.

4. Creationism (Judeo-Christian model): Earth ~6000 years old; populations created are fixed and perfect designed by God (book of Genesis) Natural theology: discovering Creator’s plan by studying nature; to classify nature • Idea strongly held until 20th Century and were followed by scientists

5. Linnaeus: founder of taxonomy; binomial nomenclature (homo sapiens) • Domain – Kingdom – Phylum – Class – Order – Family - Genus – Species • (Do Keep Precious Creatures Organized For Grumpy Scientists) • Domains = Eubacteria, Archaea, Eukarya • Classification based on anatomy & morphology. Similarities in structure ≠ related Carolus Linnaeus1707-1778

6. Cuvier: • Paleontologist – studied fossils • Deeper strata (layers) of sedimentary rocks - very different fossils from current life • From one strata to next, some species appear while others disappear (extinction) • Catastrophism – catastrophe destroyed many living species, then repopulated by immigrant species George Cuvier (1769-1832)

7. Formation of sedimentary strata with fossils

8. James Hutton1726-1797 Hutton / Lyell: Gradualism = geologic change results from slow & gradual, continuous process Uniformitarianism = Earth’s processes same rate in past & present therefore Earth is very old • Slow & subtle changes in organisms  big change Charles Lyell1797-1875

9. Jean-Baptiste Lamarck1744-1829 Lamarck: • Published theory of evolution (1809) • Importance: Recognized species evolved using evidence of fossil record and lines of descent of life (although explanation was flawed) • Use and Disuse : parts of body used  bigger, stronger (ie. Giraffe’s neck) • Inheritance of Acquired Characteristics : can be passed on

10. B. The Origin of Species – Natural Selection Thomas Malthus (1766-1834) Malthus: • More babies born than deaths • Consequences of overproducing within environment = war, famine, disease (limits of human pop.) • Struggle for existence

11. Charles Darwin (1809-1882) • English naturalist • 1831: joined the HMS Beagle for a 5-year research voyage around the world • Collected and studied plant and animal specimens, bones, fossils • Notable stop: Galapagos Islands

12. Darwin’s Research • Job on HMS Beagle was to chart South American coastline • Noted and collected many plants and animals but also their environments • Hypothesized that the Galapagos had been colonized by organisms that strayed from South America

13. HMS Beagle (1831-1836)

14. Galapagos Islands

16. Finches that Darwin collected in the Galapagos Islands The birds were all about the same size, but the shape and size of the beaks of each species were different.

17. Giant Tortoise The vice-governor of the Galapagos Islands told Darwin that he could tell which island a particular tortoise came from by looking at its shell.

18. Galapagos Tortoises

19. What happened after the voyage? • Although Darwin returned to England in 1836, he didn’t write down his ideas until 1844 • Alfred Wallace sent manuscript to Darwin to read. Very similar ideas to Darwin (Wallace did research in East Indies). • Wallace’s manuscript published first in 1858. Wallace agreed Darwin’s work on “natural selection” was better and Darwin should get main credit in his book published in 1859.

20. “On the Origin of Species by Means of Natural Selection”By Charles Darwin(1859)

21. Darwin’s Theory of Natural Selection: • Populations produce more offspring than can possibly survive. They must compete with each other for finite resources. • Individuals in a population vary extensively from each other, mostly due to inheritance. • Struggle to survive: individuals whose inherited characteristics best fit to environment leave more offspring than the less fit. • Unequal ability of individuals to survive and reproduce leads to gradual change in pop, with favorable characteristics accumulating over generations.

22. Lateral buds Terminal bud Brussels sprouts Cabbage Flower cluster Leaves Cauliflower Kale Flower and stems Stem Broccoli Kohlrabi Wild mustard Figure 22.10 Darwin’s Logic • Used Malthus’ essay to make connections • Organisms over reproduce, leading to “struggle for existence” • Used farmers’ selective breeding of plants & animals called artificial selection • Picking only desired traits makes current species have little resemblance to wild ancestors • Traits must be heritable

23. Therefore, if humans can create substantial change over short time, nature can over long period of time.

24. “Descent with modification” was main term used, not evolution. • Populations evolve, not individuals. • Fitness is determined by the environment. In summary: Natural Selection = differential success in reproduction Product of natural selection = adaptations of populations to environment

25. C. Evidence for Evolution • Evidence for evolution can be observed indirectly (things in the past or already present now) or directly (document process in our lifetimes)

26. 1. Direct – Guppies in Aripo River, Trinidad • Pond 1: main predator is killifish – eats small (immature) guppies • Avoid death: mature fast • Pond 2: main predator is pike-cichlid – eats large (mature) guppies • Avoid death: grow slowly, reproduce when small • Pond 3: killifish present, guppies absent • Take guppies from pike-cichlid pond, introduce them here, observe over time

27. POND 1 Killifish Faster-maturing guppies POND 2 Pike-cichlid Slower-maturing guppies Null hypothesis: If evolution does not occur, the transplanted slow-maturing guppies (small) will be eaten by the killifish. POND 3 Killifish Slower-maturing guppies Killifish eats small guppies GROW FAST! Pike-cichlid eats Large guppies STAY SMALL!

29. POND 3 Killifish • Results: guppies started maturing faster to avoid predation! They evolved via natural selection. Slower-maturing guppies Faster-maturing guppies

30. 2. Direct – Drug-resistant HIV • Important drug in war on HIV is 3TC • Blocks HIV enzyme reverse transcriptase from inserting HIV RNA into human DNA • Some HIV have natural 3TC-resistant reverse transcriptase but are rare • When patients go on 3TC treatment, over time, only viruses present are resistant strain Patient No. 1 Patient No. 2 Percent of HIV resistant to 3TC Patient No. 3 Weeks

31. 3. Direct – MRSA bacteria • Staphylococcus aureus (S. aureus) bacteria lives on our skin • A rare strain, Methicillin-resistant S. aureus (MRSA) exists • Patients with compromised immune systems (sick, elderly, infants, HIV, etc.) are at great risk • Common antibiotics won’t work because over time, bacteria have acquired resistance to methicillin-based antibiotics

32. The Rise of MRSA(methicillin-resistant Staphylococcus aureus)

33. 4. Direct - Peppered Moths in England • Light gray camouflaged with light trees (light 98%, dark 2%) • Pollution from factory soot made trees dark • Over time, dark moths better camouflaged (light 2%, dark 98%)

34. 5. Direct - Insects Resistant to DDT • Pesticide DDT was widely used to kill mosquitoes to prevent malaria and other mosquito-borne illnesses (banned in USA in 1972) • Almost half of mosquitoes in areas where DDT is still widely used are resistant

35. 1. INDIRECT - Biogeography • Geographic distribution of a species • Close relatives in close proximity • Geographic, reproductive isolation • Similar niches(similar environment), similar phenotype (physical appearance) even though they may be endemic (unique, found no where else) • “similar problems, similar solutions”

36. 2. INDIRECT – Fossil Record • Fossil record provides a view of past life • Found in sedimentary rocks (many layers) • Increasing complexity • Similarities between past and present • Transitional forms = links to modern species

37. 3. INDIRECT – Comparative Anatomy • Homologous structures (i.e. mammals forelimbs) • Vestigial structures/organs (i.e. appendix, wings in flightless birds)

38. 6 5 4 3 2 1 4. INDIRECT – Embryology WHICH ONE IS WHICH? chick fish human rabbit salamander tortoise Human embryo Chicken embryo • i.e. gill pouches in vertebrates • i.e. Tails in humans Gill pouches Post-anal tail

39. 5. INDIRECT – Molecular Biology • DNA & proteins: similar in species with common ancestors • Hemoglobin protein most similar between humans and rhesus monkeys (closely related) • mRNA codons identical throughout life • Same language – same origin