Darwin s Theory of Evolution The Puzzle of Life s Diversity Chapter 15-1

Transcription

1 Darwin s Theory of Evolution The Puzzle of Life s Diversity Chapter 15-1

2 WRITE A DEFINITION: EVOLUTION: change over time; the process by which modern organisms have descended from ancient organisms THEORY: a well-supported testable explanation of phenomena that have occurred in the natural world FOSSIL: the preserved remains of ancient organisms

3 Evolution is a ; theory a testable explanation of naturallyoccurring phenomena evolution The fossils that Darwin found caused him to ask questions that led to his proposal of the theory of. evolution Fossils provide evidence to support the theory of. evolution theory The fossil record provides for some of the evidence that supports the theory of evolution fossil

4 REMEMBER! The total variety of all the organisms in the biosphere = BIODIVERSITY Where did all these different organisms come from? How are they related?

5 What scientific explanation can account for the diversity of life? ANSWER: A collection of, Scientific facts, observations and hypotheses known as EVOLUTIONARY THEORY

6 The person who contributed the most to our understanding of evolution was Charles Darwin In 1831, at age 22, he joined the crew of the H.M.S. Beagle as a naturalist for a voyage around the world. 5 year

7 During his travels, Darwin wrote thousands of pages in his journals, drew pictures of the things he saw, and collected a vast amount of evidence that led him to propose a revolutionary hypothesis about the way. life changes

8 DARWIN WONDERED? Why do Argentina and Australia have different animals even though they have similar grassland ecosystems? Why are there no rabbits in Australia and no kangaroos in England? Why have so many species disappeared? How are these extinct species related to living species?

9 Who Was Charles Darwin? While on his voyage around the world aboard the H.M.S., Beagle Charles Darwin spent about one month observing life on the. Galápagos Islands There, he encountered some unique animals, such as finches and. tortoises

10 The Galάpagos Islands are close together but have very different. climates Some were hot and dry, with little vegetation. Others had more rainfall and were rich in vegetation Each island had its own unique assortment of plant and animal species.

11 Giant Tortoises of the Galápagos Section 15-1 Pinta Island Intermediate shell Islands Marchena and on Pinta Island, tortoise necks were somewhere in between Pinta Tower Fernandina James Santa Cruz Isabela Island Dome-shaped shell Isabela Floreana while on the lush rainforest of Isabela Island, tortoises had short necks Santa Fe Hood Hood Island Saddle-backed shell On the desert-like Hood Island, tortoises had long necks

12 After his voyage, Darwin spent a great deal of time thinking about his findings. He began to wonder if animals living on different islands had once been members of the same species that had developed different characteristics after becoming isolated from one another in different habitats.

13 Darwin s Theory of Evolution Ideas that Shaped Darwin s Thinking Chapter 15-2

14 Ideas that shaped Darwin s thinking: In 1785 James Hutton proposes that the Earth was shaped by geological forces occurring over very long periods of time, and is millions of years old.

15 Ideas that shaped Darwin s thinking: In 1833 Charles Lyell explains that the geological processes still occurring now have shaped Earth s features over long periods of time

16 Ideas that shaped Darwin s thinking: Theory of Pangaea and continental drift

17 REMEMBER! Chapter 3 competition Living things must compete for food, shelter, space, mates

18 Ideas that shaped Darwin s thinking: Thomas Malthus (1798) He observed that babies were being born faster than people were dying. He reasoned that if the human population continued to grow, sooner or later there would be insufficient space & food

19 Ideas that shaped Darwin s thinking: Jean-Baptiste Lamarck (1809) was one of first scientists to recognize living things changed over time and that all species were descended from other species. Lamarck published his hypothesis of Inheritance of Acquired traits the year Darwin was born.

20 The male fiddler crab uses its front claw to attract mates and ward off predators. Through repeated use, the front claw becomes larger. The fiddler passes on this acquired characteristic to its offspring

21 What s wrong with Lamarck s hypothesis? Lamarck didn t know about genes and how traits are. inherited If you lifted weights your whole young adult life, and then you had children, would your kids be more muscular? NO! Acquired traits may help an organism, but they won t be passed on to offspring.

22 What s right with Lamarck s hypothesis? Lamarck was first to develop a scientific hypothesis about evolution and recognize that organisms are adapted to their environments

23 Match the letter of the idea with the man or men who proposed it: Malthus Hutton Lyell Lamarck a. The earth is really old, and slowly changes b. Living things pass changes on to their offspring, leading to species changes c. Sooner or later growing populations run out of resources d. Living things change slowly over time because of competition for resources, and pass those changes on to their offspring

24 c. Malthus Hutton a. Lyell Lamarck b. d. a. The earth is really old, and slowly changes b. Living things pass changes on to their offspring, leading to species changes c. Sooner or later growing populations run out of resources d. Living things change slowly over time because of competition for resources, and pass those changes on to their offspring

25 Section 15-3 Concept Map Evidence of Evolution includes The fossil record Geographic distribution of living species Homologous body structures Similarities in early development which is composed of which indicates which implies which implies Physical remains of organisms Common ancestral species Similar genes Similar genes

26 Darwin s Theory of Evolution Darwin Presents his Case Chapter 15-3

27 THINK ABOUT IT What do oranges, broccoli, and Butterball turkeys have to do with EVOLUTION? (Answers to come in this slide show!)

28 After Darwin returned to England in 1836 he filled notebooks with his ideas about species diversity and the process that he would later call. evolution He did not rush to publish his ideas because they disagreed with the fundamental scientific beliefs of his day. He asked his wife to publish his ideas when he died.

29 In 1858 another naturalist, Alfred, Russel Wallace wrote an essay describing his work in Malaysia that summarized the same ideas Darwin had been thinking about for 25 years!

30 Suddenly Darwin had incentive to publish the results of his work! In 1859 On the Origin of Species presented evidence and proposed a mechanism for evolution that he called NATURAL SELECTION

31 WHAT IS DARWIN S THEORY? GENETIC VARIATION is found naturally in all populations

32 WHAT IS DARWIN S THEORY? STRUGGLE FOR EXISTANCE means that members of each species must COMPETE for food, space, and other RESOURCES.

33 WHAT IS DARWIN S THEORY? Some organisms in a population are less likely to survive.

34 WHAT IS DARWIN S THEORY? SURVIVAL OF THE FITTEST organisms which are better adapted to the environment will survive and, reproduce passing on their. genes

35 Ability of an individual to and reproduce in its specific environment = fitness survive

36 Any inherited characteristic that increases an organism s chance of survival = ADAPTATION

37 WHAT IS DARWIN S THEORY? Over time, natural selection results in CHANGES in the inherited characteristics of a POPULATION. These changes increase a species fitness in its environment.

38 WHAT IS DARWIN S THEORY? DESCENT WITH MODIFICATION suggests that each species has, DESCENDED with CHANGES, from other species over time. This idea suggests that all living RELATED TO EACH OTHER species are, and that all species, living and extinct, COMMON ANCESTOR share a.

39 EVIDENCE OF EVOLUTION: 1. Artificial selection 2. Fossil record 3. Geographic Distribution 4. Homologous structures 5. Embryology 6. DNA 7. See Natural selection happen

40 ARTIFICIAL SELECTION WORKS In artificial selection, NATURE provides the variation through mutation and sexual reproduction and humans select those traits that they find. useful EX: We have selected for and bred cows to produce more milk, turkeys with more breast meat, etc.

41 Breeds of Dogs Chihuahua bred from Techichi of Mexico by Mayans, had religious significance Saint Bernard bred by monks around 1050 A.D. to rescue travelers of mountain passes in the Swiss Alps between Italy and Switzerland Irish Wolfhound bred in Ireland to hunt wolves and elk Dachshund bred in Germany as early as the 15 th century to hunt badgers

42 ARTIFICIAL SELECTION WORKS

43 How Do We Know Evolution Happens? 2. The Fossil Record Fossils are the remains of ancient organisms found in layers of rock in the Earth.

44 How Do We Know Evolution Happens? The layers of rock tell the history of the, Earth while the fossils found within the rock tell a history of. life The fossils are thought to be the same age as the rock they are found in.

45 Movement of Earth s Crust Earthquakes and volcanoes cause uplifting of the layers of the Earth, taking the fossils along Sea level Fish die in the ocean and are covered in sediment. Over time and under increasing pressure, the remains becomes fossilized Sedimentary rocks form in horizontal layers. When part of Earth s crust is compressed, a bend in a rock forms, tilting the rock layers. As the surface erodes due to water, wind, waves, or glaciers, the older rock surface is exposed. Fossils of marine fish found on the mountainsides of southwest Wyoming, which at one time was covered by an inland sea

46 TRANSITIONAL FOSSILS HAVE BEEN FOUND

47 If Darwin s theory is correct you would closely related different species living in a geographic expect to find yet region as they spread into nearby habitats and evolve. That s EXACTLY what we do see!

48 REMEMBER THE GALAPAGOS TORTOISES? Intermediate vegetation Intermediate necks Little vegetation Long necks Lots of vegetation Short necks Tortoises adapted to different habitats as they spread from the mainland to the different islands. = DIVERGENT EVOLUTION = ADAPTIVE RADIATION

49 GALAPAGOS FINCHES The beaks of Galapagos finches have adapted to eating a variety of foods.

50 If Darwin s theory is correct you would also expect to find far apart different species living in geographic regions more alike but similar habitats becoming as they adapt to. similar ecosystems That s EXACTLY what we do see!

51 Whales and sharks have a similar body design even though they are very different organisms (one is a fish; the other, a mammal) because they have independently adapted to living in a similar environment. = CONVERGENT EVOLUTION

52 Whales are closely related to wolves, but don t look or act much like them = divergent evolution Conclusion: The pressure of the environment drives evolution Whales are distantly related to sharks, but look and act more like them = convergent evolution

53 4. HOMOLOGOUS Structures

54 4. Homologous Body Structures Structures, like the limbs of vertebrates, look very different, but are made from the, same bones because they are made from the same clump of undifferentiated cells in the. embryo

55 Figure Homologous Body Structures Section 15-3 Turtle Alligator Bird Mammal Ancient lobe-finned fish

56 4. Homologous Body Structures Some homologous body structures are vestigial and have no useful function even though they are still present, like in hipbones whales and boa constrictors.

57 Most mammals have a pouch between their small and large intestine that contains bacteria to digest plants called a. cecum In humans the cecum is shrunken and unused. It is our appendix

58 Why grow a tail and then lose it? HUMAN EMBRYO has a tail at 4 weeks tail Tail disappears at about 8 weeks

59 Skinks are a type of lizard. In some species, legs have become so small they no longer function in walking. Why would an organism possess organs with little? or no function One explanation: The gene code is present to make the organ, but function has been lost through. change over time If the organ is not vital to survival, then natural selection would not cause its elimination.

60 5. Similarities in Embryology Embryos of many animals with backbones are very similar.

61 It is clear that the same groups of undifferentiated cells develop in the same order to produce the same tissues and organs of all vertebrates, suggesting that they all evolved from a. common ancestor

62 6. Similarities in DNA Similarities in DNA and PROTEIN sequences suggest relatedness

63 Human- 46 chromosomes Chimpanzee- 48 chromosomes Similar karyotypes suggest an evolutionary. relationship

64 1. BANDING PATTERN MATCHES If you take the two smaller chromosomes apes have that we don t, and place them end to end, the banding pattern is identical to the #2 human chromosome we have. that they don t

65 2. TELOMERES IN MIDDLE Chromosomes have special sequences called telomeres at their ends to protect the strands during replication.

66 2. TELOMERES IN MIDDLE Telomere sequences are found at the ends and ALSO IN THE MIDDLE of human chromosome #2 suggesting it was made by fusing two other chromosomes together.

67 3. EXTRA CENTROMERE Chromosome #2 has a second INACTIVE CENTROMERE region

68 Did you ever wonder why dogs and cats don t need to eat, fresh fruit but YOU? DO

69 Fish, amphibians, reptiles, and most mammals can make their own VITAMIN C, but humans need to eat fresh fruit or they end up with. SCURVY

70 Human DNA contains the gene that codes for the enzyme to make vitamin C, but it is. NONFUNCTIONAL Guess what other group of organisms lack the ability to make their own Vitamin C? PRIMATES which includes chimpanzees, orangutans, gorillas, and other apes.

71 Humans have many other nonfunctional vestigial genes called. PSEUDOGENES EX: Humans have more than 99 different odor receptor genes, but more than 70% of them are nonfunctional.

72 WHY DOES EVOLUTION MATTER NOW? Can see Natural selection happen 7. EX: Peppered Moths Typica Carbonaria There is a natural variation in populations of peppered moths. Typica form - lighter Carbonaria form - darker

73 The light colored form was the predominant form in England. prior to the Industrial Revolution Around the middle of the 19 th century the darker form began to appear. It was first reported in By % of the moths in Manchester were the dark variety. In recent years, the burning of cleaner fuels and Clean Air regulations has reduced the pollution there and the lighter colored moths have increased in numbers.

74 Can see Natural selection happen 7. EX: Changes in disease-causing microbes that produce new organisms and new. diseases Bird flu HIV Antibiotic-resistant tuberculosis