1. Evolution and Natural Selection Introduction to Biology

2. Topic: Evolution

3. Topic: The Human BodyTopic: Evolution

4. Topic: The Human BodyTopic: Evolution

5. The “Fog-Basking” Beetle The “Fog-Basking” Beetle is a species that only lives in the deserts of southwestern Africa. This beetle has an unusual behavior – it stands on its head. o This allows the beetle to collect water from the fog that passes by on its body. o The water then runs down into its mouth.

6. This is a behavioral adaptation, a specific action that increases its chances of survival. Most of the beetle’s other characteristics are the same as every other beetle on Earth. o Hard shell o Six legs o Two pairs of wings How did this new species of beetle evolve? What is its relationship with other beetles?

7. Evolution Evolution is the theory that every species that exists on Earth is a descendent of an ancient ancestor. o If you were to trace the history of any two species back far enough, they will eventually intersect. All species have a common ancestor.

8. Vegetable Evolution Many of the green vegetables we eat came from the same original ancestor, and were bred for different characteristics. This is an example of selective breeding, because these breeds were created by human action.

9. Before Darwin Philosopher Lamarck hypothesized that can evolve new traits based on their actions and lifestyle. According to his theory, the giraffe developed its long neck by stretching it to eat from trees. o This is called an acquired trait because it developed over a single lifetime.

10. Before Darwin As the 19th century dawned, it was generally believed that species had remained unchanged since their creation However, a few doubts about the permanence of species were beginning to arise

11. Darwin’s Research As a boy and into adulthood, Charles Darwin had a consuming interest in nature After graduation, he went on a voyage around the world on a ship called the HMS Beagle as the ship’s naturalist. This meant he made careful observations and kept detailed notebooks of what he saw on the journey.

12. The Voyage of the Beagle During his travels on the Beagle, Darwin was able to observe adaptations of plants and animals from many diverse environments. o Rainforests of Brazil o Grasslands of Argentina o Mountains of Peru One of the most important visits he made was to the Galápagos Islands west of South America

13. NORTH AMERICA SOUTH AMERICA AFRICA EUROPE AUSTRALIA PACIFIC OCEAN ATLANTIC OCEAN England Cape of Good Hope Cape Horn Tierra del Fuego Galápagos Islands Darwin in 1840, after his return HMS Beagle in port Equator Tasmania New Zealand Andes

14. The Galapagos Islands Darwin found animals on these islands that weren’t found anywhere else in the entire world. He theorized that the animals had migrated from South America and then began developing specific adaptations to their new environment.

15. The Galapagos Islands Darwin noticed that the plants and animals changed as he went from island to island. For example, the shape of a tortoise’s shell could be used to identify which island the tortoise lived on.

16. The Galapagos Islands Darwin also noted that the animals on the Galapagos islands were amazingly unafraid of humans. After watching a lizard that was partly buried in the sand, he wrote this: “I then walked up and pulled it by the tail; at this it was greatly astonished, and soon shuffled up to see what was the matter; and then stared me in the face, as much as to say, “What made you pull my tail?”

17. Darwin’s Focus on Adaptation Darwin noted many adaptations, or characteristics that enhanced the organisms chances of survival. He began to form a theory that as organisms gradually accumulated new adaptations, they would form a new species. o One of the best examples of this theory is the different species of finches on the islands. o The birds were all very similar except for their beaks.

18. The long, sharp beak of the cactus ground finch (Geospiza scandens) helps it tear and eat cactus flowers and pulp. The large ground finch (Geospiza magnirostris) has a large beak adapted for cracking seeds that fall from plants to the ground. The green warbler finch (Certhidea olivacea) used its narrow, pointed beak to grasp insects.

19. The Origin of Species In 1844, Darwin wrote an essay on the origin of species and natural selection. The ideas of Origin of Species can be summarized with these two main points: o Evolution explains life’s unity and diversity. o Natural selection is a cause of evolution.

20. Descent with Modification Darwin did not call his theory “evolution”. He used the phrase descent with modification. o This means that all organisms are related. o All species came from a common ancestor. In the Darwinian view, the history of life is like a tree with branches representing each new species. o Each new species is simply a “modified” version of its ancestor.

21. Hyracoidea (Hyraxes) Sirenia (Manatees and relatives) Years ago 0 10,000 2 5.5 Millions of years ago 24 34 Moeritherium Barytherium Deinotherium Mammut Platybelodon Stegodon Mammuthus Elephas maximus (Asia) Loxodonta africana (Africa) Loxodonta cyclotis (Africa)

22. You are done with notes today.

23. Natural Selection According to Darwin, evolution occurs because of natural selection : over time, changes occur in the inherited characteristics of a population in order to increase a species’ fitness in the environment. An organism’s FITNESS is how well adapted they are to their environment. An organism with a high level of fitness is “a good fit” to their environment and will live and reproduce successfully. An organism with a low level of fitness is “not a good fit” and will not live as long, and most likely to live to pass their traits to future generations.

24. Fitness Which organisms have a higher level of fitness? Which organisms will live to pass their traits onto offspring?

25. Components of Darwin’s Theory 1) Survival of the fittest: Organisms that are better adapted to the environment survive and therefore live to reproduce more successfully than organisms not well adapted

26. Components of Darwin’s Theory 2) Adaptation : changes that occur in a population as it responds to environmental changes Example: camouflage

28. Components of Darwin’s Theory 3) Overproduction: more offspring are usually produced than can survive Example: fish produce millions of eggs since only 1% actually survive

29. Components of Darwin’s Theory 4) Competition : Due to overproduction, there is competition, or a struggle for survival between organisms for resources (space, food, water, light, minerals, etc.)

30. Components of Darwin’s Theory 5) Variation : certain members of a population have different traits (variations) that make them better adapted to survive. Traits that help an organism survive in a changing environment are passed on to the next generation, and the beneficial traits gradually become part of the species.

31. Components of Darwin’s Theory 6) Evolution of new species ( speciation ) Over long periods of time, variations accumulate in a population. Eventually, there are so many that the population becomes a new species.

32. Key Points The most change occurs in sexually reproducing organisms with many mutations. Individual organisms do not change to meet their needs. Groups of organisms or an entire species may change in response to a change in the environment through a succession of tiny changes over many generations.

33. You are done with notes today.

34. Evidence of Evolution Evolution is a theory. As a theory, some aspects of it may be changed as new discoveries are made, but there is a large amount of evidence to support the idea in general. There are 6 main reasons why scientists support evolution: Fossil EvidenceCellular Evidence Skeletal EvidenceMolecular Evidence Embryonic EvidenceVestigial Evidence

35. The Fossil Record The fossil record is the most important evidence of evolution. If two species are related, then transitional forms of species should exist. These are organisms that have characteristics of the ancient ancestor and the modern organism. o For example, if snakes and lizards are related, there should be evidence of snakes gradually losing their limbs.

36. Python with tiny hind leg bones (vestigial) 95 million year-old snake fossil

37. Skeletal Evidence Homologous structures are specific parts of the anatomy that show small variations on a common design. o Example: Human arm: Used for lifting and using tools Cat leg – Used for walking and climbing Whale fin – Used for swimming Bat wing – Used for flying

38. LE 22-14 Human Cat Whale Bat

39. Embryonic Evidence Comparative embryology is the common characteristics of two organisms in the embryo stage.

40. LE 22-15 Chick embryo (LM) Human embryo Pharyngeal pouches (gill slits) Tail

41. Cellular Evidence Despite major outward differences, all cells are basically similar in structure. For instance, all cells have DNA, cytoplasm, and cell membranes. In terms of evolution, this is evidence that different kinds of living things may share a common ancestor.

42. Molecular Evidence Similarities can also be present at the molecular level. Sequences of DNA in chromosomes, or sequences of amino acids in proteins can be compared to see how closely related two organisms may be.

43. LE 22-16 Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide 100% 95% 87% 69% 54% 14% Rhesus monkey Species Human Mouse Chicken Frog Lamprey

44. Vestigial Evidence Vestigial structures are remnants of structures that were important in the organism’s ancestors, but are no longer necessary. o In humans, examples of vestigial organs would include: The appendix Tailbone Wisdom teeth

45. Vestigial Structures

46. You are done with notes today.

47. Population Genetics Darwin’s theory of evolution is still widely accepted today, but modern evolutionary theory combines Darwin’s ideas of variations and natural selection with our knowledge of genetics. In genetic terms, evolution is any change in the relative frequency of alleles in a population’s genes.

48. Population Genetics The gene pool is the set of all genes in any population, usually of a particular species. The larger the gene pool, the greater the genetic diversity and the better chance a species has of surviving an environmental change.

49. Boar Gene Pool

50. Dog Gene Pool

51. Genetic Diversity There are two main sources of genetic diversity: o sexual reproduction (gene shuffling and recombination) o mutations

52. You are done with notes today.

53. The History of Life The study of fossils helped to lay the groundwork for the development of the theory of evolution. Fossils are remains or traces of organisms from the past, usually found in layers of rock.

54. Grand Canyon

55. The Fossil Record Fossils are formed in layers by age, with the oldest layers on the bottom and more recent layers on top, closer to Earth’s surface.

56. The Fossil Record Fossils tell the history of the Earth: Life began 4.6 billion years ago as simple, unicellular prokaryotic organisms. Around 1.5 billion years ago, life diversified as increasingly complex multicellular organisms appeared on Earth.

57. The Earth’s Timeline

58. The Fossil Record Fossils tell how life has changed on Earth: Of all the species that have existed on earth, 99% have become extinct, or completely disappeared. Extinctions usually occur when the environment changes and species cannot adapt fast enough to survive.

59. You are done with notes today.

60. Human Evolution Very little is known about human evolution, due to the lack of fossil evidence. People often incorrectly assume that Darwin believed humans evolved from apes. Darwin only suggested that humans, along with other mammals, could have shared a common ancestor.

61. Human Evolution Scientists agree that humans have evolved into a dominant force on earth today because we have certain physical characteristics that enable us to function more efficiently than other mammals.

62. Human Evolution Examples include: superior brain that allow reasoning, speaking, and the use of tools prehensile hand (hand with opposable thumb), used to grasp tools

63. Human Evolution More examples: upright posture that frees the arms for use in activities other than support and movement excellent vision – able to see things in 3-d

64. You are done with notes today.

65. Pesticide-Resistant Insects The theory of evolution can be observed around us today. Examples include: Insect resistance to DDT (ex. mosquitoes & black flies)

66. Antibiotic-Resistant Bacteria Antibiotic- resistant bacteria (for example: MRSA)

67. Drug-Resistant HIV Drug-resistant HIV

68. English Peppered Moths 150 years ago, the peppered moth was light colored. As pollution increased during the Industrial Revolution in England the trees became blackened by soot and most of the light colored moths died out. The mutation for dark coloration became beneficial, and these moths increased in number.

69. You are done with notes today.

70. The Evolution of Darwin’s Finches There are now at least 13 species of finches on the Galapagos Islands, each filling a different niche on different islands. All of them evolved from one ancestral species, which colonized the islands only a few million years ago. This process, whereby species evolve rapidly to exploit empty ecospace, is known as adaptive radiation.

72. Darwin’s Finches The original finches on the Galapagos Islands ate seeds (plant food). As competition for seeds increased, some finches evolved to fit new habitats, their beaks changing to eat different types of food. Some Galapagos finches now also eat insects (animal food).

74. How to Read the Finch Food Wheel

75. You are done with notes today.

76. Cladograms Cladograms are diagrams used to show evolutionary relationships. Much like a family tree, the closer two species are on the tree, the more closely they are related.

77. Cladograms Since cladogram branches are similar to life lines, if a branch stops short and does not extend to the top of the tree, that species has become extinct. If two lines converge (come together), two species have become one. If two lines diverge (split), one species has become two, indicating speciation has occurred.

78. Cladograms

79. You are done with notes today.

80. Classification Classification is the grouping of different organisms based upon similarities in structure and evolutionary relationships. Organisms are classified into 7 different (groups): Kingdom(largest group: has the most organisms) Phylum Class Order Family Genus Species(most specific group: only 1 organism)

81. Classification Scientists have developed a tool to help classify organisms called a dichotomous key. A dichotomous key uses a series of 2-part questions to figure out what species an organism is. To use a dichotomous key, begin at question one and answer the questions. Each answer will end in another direction or the name of the species.

83. You are done with notes today.