Campbell & reece : Chapter 22

1. Campbell & reece:Chapter 22 Descent with Modification: A Darwinian View of Life

2. 3 key observations about life Striking ways organisms are suited to their environment Unity of living things(so many common features) Rich diversity of life

3. EVOLUTION DESCENT WITH MODIFICATION

4. EVOLUTION A CHANGE in the GENETIC COMPOSITION of a POPULATION from GENERATION to GENERATION

5. EVOLUTION • CAN BE VIEWED IN 2 WAYS • A PATTERN • OBSERVATIONS FROM NATURAL WORLD • A PROCESS • MECHANISMS THAT PRODUCED THE OBSERVED PATTERNS

6. ARISTOTLE(384 – 322 BCE) • DID NOT BELIEVE ORGANISMS CHANGED OVER TIME (some Greeks did) • Viewed organisms as fixed: could be arranged on ladder from least complex  most complex

7. SCALAE NATURAE

8. CAROLUS LINNAEUS(1701 – 1778) • DEVELOPED BINOMIAL NOMENCLATURE • WITH A “NESTED” CLASSIFICATION SYSTEM

10. LINNAEUS CLASSIFICATIONSYSTEM

11. PALEONTOLOGY • STUDY OF FOSSILS • GEORGES CUVIER (1769 – 1832) • OLDER THE STRATUM OF SEDEMENTARY ROCK THE OLDER & MORE DISSIMILAR THE FOSSILS WERE TO CURRENT LIFE • NEW SPECIES APPEARED, SOME DISAPPEARED

12. GEORGES CUVIER CATASTOPHISM: EVENTS IN THE PAST OCCURRED SUDDENLY & WERE CAUSED BY DIFFERENT MECHANISMS THAN SEEN NOW

13. JAMES HUTTON(1726 – 1797) • Scottish Geologist • Explain geologic features by gradual mechanisms still going on now

14. CHARLES LYELL(1797 – 1875) • Principle of Uniformitarianism • Mechanisms of change are constant over time

15. Hutton & Lyell’s ideas influenced Darwin • Both indicated Earth had to be much older than previously believed • Darwin reasoned: slow & subtle processes could produce biological changes

16. Lamarck’s Hypothesis of Evolution • 1st to propose mechanism of evolution • Parts of body used the most become larger, stronger; parts not used deteriorate • Inheritance of Acquired Traits

17. LAMARCK(1744 – 1829) • EVOLUTION HAPPENS BECAUSE ORGANISMS INATELY WANT TO BECOME MORE COMPLEX

19. CHARLES DARWIN(1809 -1882)

20. VOYAGE of the BEAGLE1831 - 1836

21. Darwin’s Observations • Plants & animals in temperate zones of SA closely resembled plants & animals of temperate regions of Europe • Fossils in SA resembled living organisms in SA

22. GALPÁGOS

23. Darwin’s Observations: Descent with Modification • Took note of many adaptations  saw adaptations & the origin of a new species as closely related processes

24. Darwin’s Finches • 14 different species each clearly adapted to a specific niche • all similar to finches on mainland SA (common ancestor)

26. Darwin’s Theory • Proposed that natural selection over long periods of time could cause an ancestral species to give rise to 2 or more descendant species

27. Natural Selection: a process in which individuals with certain inherited traits tend to survive & reproduce at higher rates than other individuals without those traits

28. The Origin of the Species by Means of Natural Selection • Darwin provided massive amounts of evidence that descent with modification by natural selection explains : • Unity of Life • Diversity of Life • Match between Organisms & their Environment

29. Natural selection Artificial selection

30. Darwin’s Reasoning Observations Inferences • There are variations of traits in populations • Individual with variations that are favorable will leave more offspring than one without those traits

31. Darwin’s Reasoning Observation inference 2. Species produce more offspring than can survive 2. overpopulation leads to competition, those with traits that will help them survive  reproduce more  passing along favorable traits

32. SURVIVAL of the FITTEST

33. Over time natural selection increases the match between organisms & their environment

34. When the environment changes natural selection may result in adaptations that give rise to a new species

35. Natural Selection in response to invasive species Balloon vine Goldenrain Tree

36. SOAPBERRY BUGS • SEEDS BURIED DEEPER IN PODS OF NATIVE PLANT, BALLOON VINE • BUGS THAT FEED ON INVASIVE GOLDENRAIN PODS NOW HAVE SHORTER BEAKS

37. CONCLUSION • CHANGING THE ENVIRONMENT CAN RESULT IN EVOLUTION BY NATURAL SELECTION FOR MATCHING BEAK SIZE

38. DRUG-RESISTANTBACTERIA • Normal for 1 out of 3 people to have Staph aureus on skin • MRSA • (methicillin-resistant staph aureus) • Can be fatal

39. Developing drug-resistance

41. Rise of MRSA hospital acquired infections 1993 - 2005

42. From study done in Atlanta area in 2006

43. Soapberry bug & MRSA both examples of • 1. natural selection does not “create” it “selects” for variants already present in population • 2. natural selection depends on time & place

44. HOMOLOGY • SIMILARITY RESULTING FROM COMMON ANCESTORS

45. Homologous Structures: Embryology • Similarities in early stages of development suggest common ancestry • At some point in development all vertebrates have a tail

46. VESTIGIAL STRUCTURES • REMNANTS OF FEATURES THAT WERE IMPORTANT IN EVOLUTIONARY ANCESTOR

47. Molecular Homologies • All life forms use DNA & RNA • Genetic code is universal • Some human genes code for exact same protein as bacterial gene • +/- have same function • Some organisms carry “vestigial genes”

48. Evolutionary Tree • Can organize organisms with shared characteristics in nested groups • Deepest layer all living things share • Each successive smaller group have their own unique homologies

50. Evolutionary Trees • are hypotheses that summarize our current understanding of patterns of descent