1. Who Was Charles Darwin? Label your paper : 1. 2. 3. 4. 5. Write 5 facts from the short video clip on Darwin… http://www.pbs.org/wgbh/evolution/library/11/2/e_s_2.html

3. Darwin’s Observations Animals on the coast of South America: Resembled those on the nearby islands Evolved differences Or Descended w/ modification after separating from a common ancestor.

4. Darwin’s Great Voyage!!! http://www.pbs.org/wgbh/evolution/educators/lessons/lesson2/act1.html

5. Evolution of Populations: Natural Selection

6. Gene Pools A gene pool refers to all the genes, including the different alleles, that are present in a population genetic diversity was the sum total of all genetic information carried by ALL organisms living on Earth.

7. Gene Pools Genetic diversity is the total of all genetic information carried by ALL organisms living on Earth. The relative frequency of an allele is the number of times that allele occurs in a gene pool.

8. Gene Pools Evolution is any change in the relative frequency of alleles in a population

9. Sources of Genetic Variation The two main sources of genetic variation are mutations and the genetic shuffling that results from sexual reproduction.

10. Sources of Genetic Variation 1.Mutations are changes in a sequence of DNA, due to mistakes in the replication of the DNA or due to damage from radiation or chemicals in the environment.

11. Sources of Genetic Variation 2.Gene shuffling occurs during the production of gametes – you do not look exactly like either of your parents due to the independent assortment of alleles that occurs during meiosis.

12. Changes in the Gene Pool Evolution is the change in frequency of alleles in the gene pool. Natural selection can lead to changes in allele frequencies and thus to evolution.

13. Natural Selection Evolutionary fitness is an organism’s success in passing genes to the next generation. An adaptation is any inherited trait that increases an individuals chance of surviving and reproducing.

14. How Does Evolution Really Work

15. Types of Natural Selection There are three types of natural selection that can occur in populations: 1.Directional 2.Stabilizing 3.Disruptive

16. Types of Natural Selection - Directional 1.Directional – when individuals with one of the extreme forms of a trait has better fitness than other forms of the trait, the range of phenotypes shifts as the individuals with lower “fitness” die out. If the supply of small seeds runs out, only birds with larger beaks will be able to eat the larger seeds and survive. Overall beak size will increase.

17. Types of Natural Selection 2. Stabilizing – the moderate form of a trait outcompetes the two extremes. Birds with intermediate sized beaks can eat a wide range of seeds (both big and small) so they have a survival advantage.

18. Types of Natural Selection 3. Disruptive – when individuals of both extreme forms of a trait outcompete the middle/moderate form.

19. DirectionalDisruptiveStabilizing

20. Genetic Drift Natural selection is not the only source of evolutionary change. In small populations, an allele can become more or less common simply by chance. This kind of random change in allele frequency is called genetic drift.

21. Genetic Drift A situation in which the allele frequencies change as a result of the migration of a small subgroup of a population is known as the founder effect.

22. How Do We Know If Evolution Is Occurring? Evolution occurs when there is a change in allele frequencies. If the allele frequencies do not change, the population is not evolving (it is in genetic equilibrium). There are five conditions that must be met for a population to be in genetic equilibrium. If any of these five conditions are not met then the population is evolving!

23. 5 Conditions for Genetic Equilibrium 1. Random Mating – every member of the population must have an equal opportunity to produce offspring. Note: Random mating is rare. Many species, including lions and wolves, select mates based on a particular heritable trait, such as size or strength. 2. Large Population – a large population size is important because genetic drift will have less of an effect.

24. 5 Conditions for Genetic Equilibrium 3. No Movement Into or Out of the Population – if individuals move into or out of a population they are taking away or bringing in genes and may upset the frequencies. 4. No Mutations – if genes mutate this will cause a change in the frequency of alleles. 5. No Natural Selection – no trait can have a specific advantage over another.

27. Evidence Supporting Evolution There are many areas of study that provide evidence for biological evolution: 1.Fossil record 2.Homologous body structures 3.Vestigial structures 4.Similarity in embryology 5.Biochemistry

28. Fossils are traces of once living organisms. When fossils are arranged by age, they show a gradual changes. Fossil Record

29. By comparing fossils from older rock layers with fossils from younger layers, scientists can document the fact that life on Earth has changed over time.

30. Fossil Record Similar organisms found in different locations, both dating to the same time period, help verify the fossil record.

31. Becoming a Fossil

32. Homologous Structures Homologous structures body parts that have similar skeletal structure but different functions. Homologous structures provide strong evidence that all four-limbed vertebrates descended from common ancestors.

33. Fish with Fingers

34. Analogous Structures A structure that has the same function but different construction and was NOT inherited from a common ancestor. Analogous structures may evolve during parallel adaptation, where similar environmental conditions in two different regions of the world cause selection for the same type of traits (like the ability to fly).

35. Vestigial Structures Vestigial Structure – body parts that have no apparent function, but resemble useful body parts of another organism. Example: appendix, tailbone, snake pelvis

36. Vestigial Structures Vestigial structures are evidence of evolution because they show structural change over time.

37. How Do We Know Evolution Really Happens?

38. Embryonic Development During embryonic development, embryos and fetuses of different species show similar characteristics.

39. Embryonic Development The same groups of embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all vertebrates. These common cells and tissues, growing in similar ways, produce the homologous structures.

40. Biochemistry Biochemical evidence for evolution is seen in the similarities in the DNA and protein molecules found in living organisms. Cytochrome C is an essential protein in the electron transfer chain of the mitochondria

41. Biochemistry Scientists have similarly compared the biochemistry of universal blood proteins. Their studies reveal evidence of degrees of relatedness between different species. This evidence implies that some species share a more recent common ancestor than other species do.

42. Cladograms A cladogram shows the relationships among organisms. It is a branching diagram depicting the points of species divergence from a common ancestral line.

45. Speciation and patterns of evolution Where do new species come from?

46. Speciation What must happen for a species to evolve into two new species? The gene pools must become separated. When the members of two populations can no longer interbreed and produce fertile offspring, reproductive isolation has occurred. At this point, there are two separate gene pools.

47. Speciation Reproductive isolation can occur in three ways: 1. Geographical Isolation – physical separation and isolation of a population from another by land bridges, earthquakes, volcanic eruptions, floods, droughts, fire, ice age, or the Grand Canyon!

48. Speciation 2. Behavioral Isolation – separation and isolation of a population from another due to differences in behavior such as courting rituals or other sexual behaviors. Example: Eastern and Western Meadowlarks sing separate mating songs

49. Speciation 3. Temporal Isolation – separation and isolation of a population from another due to different reproductive times. Example: orchids bloom in different seasons, so flowers cannot pollinate each other

50. Patterns of Evolution Certain patterns are often seen in the evolution of new species over time. 1.Adaptive Radiation (divergent evolution) - one species or a small group of species evolves into several different forms that become less and less like each other as time passes. Example: Darwin’s Finches

52. Patterns of Evolution 2. Convergent Evolution – unrelated species start to resemble each other more and more as time passes. This is due to different organisms facing the same type of environmental demands (such as moving through water), therefore they develop similar modifications Example: dolphins, penguins, sharks

53. Sharks are fish, penguins are birds, and dolphins are mammals, yet they all must move through water. Thus, their differently structured limbs have all evolved into similar looking appendages (analogous structures)

54. Patterns of Evolution 3. Coevolution – two species evolve in response to changes in each other over time. Coevolution involving flowers and insects is very common. The Madagascar orchid has a 40 centimeter spur with a supply of nectar at the tip. The hawk moth from Madagascar has an equally long feeding tube to be able to reach the nectar.

55. Patterns of Evolution There are two main thoughts on how natural selection has progressed in populations over time. Gradualism - evolution through natural selection occurs in a slow and steady nature; populations change gradually over time. Darwin favored this idea, and the fossil record confirms that many organisms have changed slowly over time.

56. Patterns of Evolution Some species, however, like the horseshoe crab, have changed very little since the time they appeared in the fossil record. They appear to be in a state of genetic equilibrium (not evolving). Some biologist suggest that most new species are produced by sudden periods of rapid change after a long period of genetic equilibrium, what they call punctuated equilibrium. This may occur when a small group of organisms becomes isolated from the main group, or after periods of mass extinction.

58. Theories of Evolution

59. Evolution Evolution is a change in the frequency of alleles over time.

60. How Did Current Organisms Develop? The first scientist to hypothesize about organisms changing over time was Jean- Baptiste Lamarck (1809). His hypothesis, called the Inheritance of Acquired Traits, proposed that by use or disuse of organs, certain traits were acquired or lost during a lifetime and that these traits could then be passed on to their offspring.

62. Natural Selection Another theory on how organisms changed over time that was proposed by Charles Darwin and Alfred Wallace (~1850). Natural selection is defined as the process by which individuals that are better suited to their environment survive and reproduce most successfully. This is also sometimes referred to as “survival of the fittest.”

63. How Does Natural Selection Work? Within every species there is variation of traits or characteristics. Organisms in nature produce more offspring than can survive, and many of those that do survive do not reproduce. Because more organisms are produced than can survive, members of each species must compete for limited resources.

64. Individuals best suited to their environment survive and reproduce the most successfully. The characteristics that make them best suited to their environment are passed on to their offspring.

65. How Does Natural Selection Work? These offspring with the advantageous trait will survive, reproduce, and pass on the advantageous trait to their offspring. This pattern continues over several generations.

66. How Does Natural Selection Work? Over a long period of time, all surviving members of a species will have the advantageous trait. This changes the characteristics or traits of a population and can lead to a change in the species. New species arise, and other species disappear. Species alive today have descended with modifications from species that lived in the past.

68. The History Life On Earth: Current Theories

69. What is a Theory? A theory is a proposed explanation for something observed in the natural world. Theories are supported by evidence from many different sources. A theory can be modified as new data becomes available.

70. How old is Earth? Geologic evidence shows that Earth, which is about 4.6 billion years old, was not born in a single event.

71. It wasn’t until 3.8 billion years ago that the Earth cooled enough so that the water vapor would condense into liquid water.

72. The Origins of Life Oparin’s Theory – Abiogenesis (1924) Aleksandr Oparin hypothesized that the origins of all life on Earth came from nonliving chemical substances which spontaneously formed in Earth's early atmosphere, then combined to make more complex chemicals until eventually living cells were formed.

73. Earth’s ancient atmosphere probably contained the gases nitrogen, methane, and ammonia but little free oxygen. Oparin theorized that energy from the sun, volcanoes, and lighting fueled chemical reactions among these gases, which eventually combined into small organic molecules. In the “primordial soup” of organic molecules, present- day cells formed.

74. Could Oparin’s Theory Be Correct? Scientists Miller and Urey conducted an experiment in the 1950’s that recreated earth’s early atmosphere in a laboratory to see if organic molecules could form, The results showed that the “primordial soup” contained amino acids (the building blocks of proteins) and two nucleotides (the building blocks of nucleic acids).

75. Miller and Urey’s Experiment 1950’s

76. What were the first cells on Earth? The first cells on Earth were single-celled prokaryotic autotrophic aquatic organisms that didn’t require oxygen. Since these bacterial cells were photosynthetic they were increasing the amount of oxygen gas in the Earth’s atmosphere.

77. How did eukaryotic cells begin? According to the endosymbiotic theory, eukaryotic cells formed when smaller eukaryotes began living inside the larger prokaryotic cells