Evolution

1. Evolution

2. Variation in Living Things SPECIES  - Group of organisms that interbreed VARIATION - small differences between individuals of a species   • Some neither helpful nor harmful   • Some enable organism to be better suited to its environment.

3. Variation in Living Things Environment constantly changing   • Some gradual - global warming; change in climates   • Some sudden - eruption of a volcano; landslide   Environmental changes may result in organisms   • Dying   • Migration to new area   Some organisms may have helpful variations that enable them to survive the changes and reproduce.   • Helpful variation inherited by offspring.   • Eventually environment contains a large number of individuals that have the helpful variation

4. Variation in Living Things ADAPTATION   • Process by which an organism becomes better suited to a change in the environment. • Helpful variation - permits survival - individual better suited to its environment.   • Examples :  Body Structure or Function Flat teeth and powerful jaws of horses - chewing grass Sharp pointed teeth of tigers - tearing meat.   Coloration - Tiger's stripes - camouflage   Behavior - Nest building of birds  

5. Evidence of Evolution EVOLUTION - Based on present scientific data • The theory that describes changes in living things and links them to changes in the environment. • Change over a period of time - not rapid.

6. Evidence of Evolution Changes in the Earth and its Environs   • Earth about 4.5 billion years old   • Early planet was ball of hot rock   Bombarded by meteorites   Volcanic eruptions released gases into the atmosphere   Surface cooled - below boiling point of water   Water vapor condensed and fell to earth as rain   Collects forming oceans - 3.8 - 3.9 billion years ago.   • Early atmosphere of the earth.   Contained ammonia, methane, hydrogen, and water vapor   Bombarded by solar radiation particularly ultraviolet

7. Evidence of Evolution Alexander Oparin - Russian scientist, 1924   • Proposed that life molecules formed from materials in early atmosphere   • Theorized that energy from lightning, volcanic eruptions, ultraviolet radiation from sun, and natural radiation of earth may have split some of the molecules of the early atmosphere. • Molecules reformed - larger, more complex organic molecules • Molecules washed from atmosphere; collected in shallow pools and oceans - formed an "organic soup" - complex molecules • Molecules worked together forming first cells.

8. Evidence of Evolution Oparin's idea tested by Stanley Miller - 1953. • Passed mixture of gases through a flask containing electrodes - simulated lightning   • Another flask contained boiling water - provided water vapor for "rain"   • "Rain" washed molecules in a collecting pool.   • Organic molecules found - amino acids  

9. Evidence of Evolution The First Cells • Quite similar to some present-day bacteria   Prokaryotic- no true nucleus   Heterotrophic- "ate" molecules in organic soup   Probably Anaerobic- atmosphere had little or no oxygen   • Primitive cells flourished - food supply abundant   • Numbers increased, food supply used up - competition increased - Cells evolved that could make their own food - autotrophic.   Photosynthetic organisms most successful autotrophs Resembled blue-green bacteria - prokaryotic, no chloroplast.   Autotrophs changed atmosphere - oxygen becomes abundant  

10. Evidence of Evolution Eukaryotic Cells • Probably appeared about 1.5 billion years ago   • Began as a small colony of prokaryotic cells; mutual survival   • Individuals may have become organelles.   Mitochondria - aerobic bacteria Chloroplasts - blue-green bacteria • Theory doesn't explain all differences between eukaryotes and prokaryotes - doesn't explain how nuclear membrane came into being.

11. Evidence of Evolution Major Types of Evidence • Fossil Evidence • Anatomical Evidence • Embryological Evidence • Biochemical Evidence

12. Evidence of Evolution Fossil Evidence   Fossils Remains or traces of organisms that lived in the past.   Found in sedimentary rock - buried in sediment   Must be buried in sediments soon after death – slows/stops decay   Types   Imprints- from soft body parts; usually carbon remains.   Mold- cavity takes shape of trapped hard body parts   Cast- Filled mold.   Petrified Fossils- Hard parts are replaced by minerals.   Whole Organisms   Frozen in ground or ice (glaciers) In amber (hardened plant resin)

13. Evidence of Evolution Interpreting Fossils   Fossils provide evidence that surface/climates have changed.   Fossils of ocean dwelling species in inland areas -   Coral fossils in cold areas - grow in warm areas   Ferns/palm tree fossils in cold areas - warm, humid areas   Fossils used as evidence of changes in life forms   Example - Horse Fossils   Fossils of horses - size of dog to present size   Change from 4 toes on foreleg and 3 toes on hindleg to 1 toe (hoof) on each leg.   Indicate many different living things have existed in the past.   Extinct - organisms that no longer lives on earth.

14. Evidence of Evolution Dating Fossils   • Fossils are useful only if scientists can tell how long ago they lived.   • Relative Age - Putting events in their proper sequence   No reference to age - order event occur Law of Superposition- sedimentary rocks, bottom layers deposited before upper layers - each layer is younger than layers below it and older than the ones above it.   • Absolute Age- how many years ago an event occurred; measured in actual years.   Uses Radioactive Decay- measure of half-life of element.   Half-Life- Time it takes for ½ of quantity of element to breakdown to another element.   Carbon 14 decays to Nitrogen 14 - half-life = 5730 years.  

15. Evidence of Evolution Geologic Time Scale   • Set up by scientist using information gained from various dating methods.   • Divided into 4 large time spans called an ERA   Precambrian Era - formation of earth to about 600 million years ago - 4 billion years long - little fossil evidence   Paleozoic Era - Lasted about 370 million years   Mesozoic Era - (Dinosaurs) - lasted about 160 million years   Cenozoic Era - Has lasted about 70 million years - Present   • 3 most recent Erasdivided into Periods • Some Periodsdivided into Epochs

16. Evidence of Evolution Anatomical Evidence   • Anatomy- Study of the structure of living things   By comparing structures of organisms, similarities are found   Use similarities as evidence of evolution   • Homologous Organs  Body parts of different species that are similar in structure   Examples   Seven neck vertebrae of all mammals   Whale's flipper, human's arm, bird's wing, etc.   Can't be explained by common function; can be by heredity; indicates common ancestor;   • Vestigial Organs Organs that are reduced in size and appear to have no use.   Examples   Human appendix   Remains of hind limbs in whales

17. Evidence of Evolution

18. Evidence of Evolution Embryological Evidence Early vertebrate embryos look very similar Believed to have common genetic material - early development similar.   Gill slits in vertebrates Notochord

19. Evidence of Evolution

20. Evidence of Evolution Biochemical Evidence Similarities between common proteins found in living organisms Similarities indicate a close relationship Indicates similarities between DNA of organisms.

21. Theories of Evolution Lamarck's Theory Jean Baptiste de Lamarck, French biologist; early 1800s   Believed giraffes' long necks result of stretching Low food supply was consumed Stretched their necks to reach higher branches Disuse of an organ could result in its loss.   Based on Inheritance of Acquired Characteristics Acquired traits passed on to the next generation   Not valid, body cells changes not passed to gametes

22. Theories of Evolution

23. Theories of Evolution Darwin's Theory   Background   British naturalist Published book;1859 On the Origin of Species by Means of Natural Selection   Ideas formed during 5 year voyage aboard the HMS Beagle Observed many different plants and animals in South America and The Galapagos Islands.

24. Theories of Evolution

25. Theories of Evolution

26. Theories of Evolution

27. Theories of Evolution

28. Theories of Evolution

29. Theories of Evolution Main Hypotheses • The world is not static but is changing • Living things change through time. • Organisms with many common characteristics descended from a common ancestor. • Evolutionary change is result of natural selection.

30. Theories of Evolution

31. Theories of Evolution Natural Selection – Process by which those organisms that are best suited to their environment survive and reproduce.

32. Theories of Evolution Factors Working in Natural Selection • Overproduction   • Struggle for Existence   • Variation

33. Theories of Evolution Overproduction • Organisms tend to produce more offspring than could survive.   • Assumed number of organisms would increase geometrically (1,2,4,8,16,32,64,128,...)  

34. Theories of Evolution Struggle for Existence   • Even with overproduction, population tended to remain constant.   • Concluded lack of population increase was due to "struggle for existence" - competition for food, space, etc.,   • Some individuals not successful; will die.   • Concluded that individuals and species were "selected" by their environment.  

35. Theories of Evolution Variation • Individuals of a species vary genetically.   • Not able to explain cause of variations.

36. Theories of Evolution Natural Selection and Origin of New Species • Better suited organisms survived and reproduced; passed traits to their offspring.   • Over time many small changes would occur, the whole population would change.   • Eventually populations become significantly different from past populations New species formed.  

37. Processes of Evolution Gene Pool All the genes of a given population Variations in gene pool cause changes in the species.

38. Processes of Evolution Hardy-Weinberg Law The frequency of dominant and recessive genes in a population remains the same from generation to generation.   • Gene Frequency- indication of relative number of individuals in a population that have a particular gene.   • Law applies only under the following conditions   Population must be very large   No new genes enter the gene pool   Mating must be random Natural selection must not be operating Mutations must not occur.

39. Processes of Evolution Major Processes at Work • Gene Mutation   • Adaptation Shifts • Migration • Isolation

40. Processes of Evolution Gene Mutation Change in genetic material Result - change of gene pool

41. Processes of Evolution Adaptation Shifts Changes in frequency of occurrence of certain genes as environment changes.  

42. Processes of Evolution Shift in Color of Peppered Moth in Manchester, England Before 1845, peppered moths were light with dark specks   In 1845 during a survey only 1 black moth was observed.   Light colored moths were difficult to see on light colored tree trunks - not eaten by birds.   Manchester - industrial center in mid 1800s Used coal for energy - large amount of soot; Settled on tree bark making it dark   By 1895, 99% of moths in area were black Black color permitted hiding Light coloration moths stand out on trees - easy food for birds.  

43. Processes of Evolution

44. Processes of Evolution Migration Movement of organisms into and out of a population Brings new genes or removes genes when organism leaves.

45. Processes of Evolution Isolation Separation of members of a population from other members.   Separation may lead to Speciation Formation new and distinct species.   Geographic Isolation- separation of population members by some geographic barrier River, mountain, canyon, etc.   Reproductive Isolation- separation of members of a population by inability to reproduce.  

46. Pathways of Evolution Processes of evolutionary change that have lead to organisms having similarities or differences.

47. Pathways of Evolution Divergent Evolution • Evolutionary pathway where different species have developed from a common ancestor Members of population spread out, adapt to various environments. Different variations are selected Adaptive Radiation - process where species adapts to set of environmental conditions • Divergentmeans "moving apart"   • Example - Darwin's finches on the Galapagos Islands   Ancestor inhabited the islands   Offspring gradually filled various environments of the islands   Some became seed eaters, others ate insects, one even became a type of woodpecker: uses a thorn as a tool.  

48. Pathways of Evolution

49. Pathways of Evolution

50. Pathways of Evolution Convergent Evolution • Process of unrelated species developing similar characteristics.   • Convergentmeans "coming together"   • Examples-   Wings of birds and bats   Body shape of whales, porpoises, and dolphins and fish Flippers of the mammals and fins of fish   • Analogous Organs - organs that are similar in appearance and function but not in origin.