1. 1 Evolution “Change Over Time” June 6 th and 7 th Dr. Block and Mr. Libretto

2. 2 I. Charles Darwin Discovered the theory of evolution which we base the Discovered the theory of evolution which we base the modern theory on today. First person to define natural selection as the driving force of evolution. First person to define natural selection as the driving force of evolution. His theories threatened the ideas proposed by religion and was very different than theories before. His theories threatened the ideas proposed by religion and was very different than theories before. Researched the wildlife of the Galapagos Islands, where he saw similarities between the species there. Researched the wildlife of the Galapagos Islands, where he saw similarities between the species there. He was reluctant to share his ideas because it was different than what people believed, and suggested a relationship between humans and other organisms. He was reluctant to share his ideas because it was different than what people believed, and suggested a relationship between humans and other organisms. If Darwin was right, this meant that humans were related to other primates (monkeys, etc.) and that they were a result of evolution, not religion. If Darwin was right, this meant that humans were related to other primates (monkeys, etc.) and that they were a result of evolution, not religion.

3. 3 II. Evidence for Evolution 1 st Source - Fossil Record The organisms alive in the past are much different than the organisms alive today. The organisms alive in the past are much different than the organisms alive today. Life on Earth changes over time. Life on Earth changes over time. The modern theory uses fossil records to identify intermediate species. This uses identifiable similarities and differences located on the fossils. The modern theory uses fossil records to identify intermediate species. This uses identifiable similarities and differences located on the fossils.

4. 4 II. Evidence of Evolution 2 nd Source – Embryonic Development (AKA: Comparative Embryology) Related organisms Related organisms look identical during early development. The similarities in The similarities in organisms during development suggest all life on Earth is related.

5. 5 II. Evidence of Evolution 3 rd Source – Homologous Structures Two body parts with similar structure but serve different functions. Two body parts with similar structure but serve different functions. Ex – The fin of a whale and arm of a human have a very similar bone structure, but have adaptation to fit different environments. This shows there is a relationship between species. (Common Ancestor) This shows there is a relationship between species. (Common Ancestor)

6. 6 Typical primitive fish TurtleAlligatorBirdMammals Homologous Body Structures Homologous Body Structures

7. 7 II. Evidence of Evolution (Modern theory) 4 th Source – Molecular Similarities All living things on Earth use the same DNA and RNA code. All living things on Earth use the same DNA and RNA code. All living things build proteins and use DNA or RNA to store their genetic material. All living things build proteins and use DNA or RNA to store their genetic material. Darwin was not aware of this evidence, since DNA wasn’t identified yet. Darwin was not aware of this evidence, since DNA wasn’t identified yet.

8. 8 includes Evidence of Evolution Physical remains of organisms Common ancestral species Similar genes which is composed ofwhich indicateswhich implies The fossil record Geographic distribution of living species Homologous body structures Similarities in early development The Modern Theory of Evolution uses all of these as Evidence of Evolution (Darwin didn’t know about genes.)

9. 9 III. Cladograms Cladograms are used to illustrate the relationships between different species. Cladograms are used to illustrate the relationships between different species. A cladogram is drawn based how close two species are related. A cladogram is drawn based how close two species are related. All species on a cladogram are eventually related to one another, some closer than others. All species on a cladogram are eventually related to one another, some closer than others.

10. 10 A B C D E F PAST Present 1.Which of the following species has the most recent common ancestor? 2.Which two species are the most closely related? 3.Which species is now extinct? 4.Species B is a common ancestor for which other species? G You will need to answer questions similar to these. An example of a Cladogram – They can be drawn in any direction

11. 11 IV. Adaptation A species will change to survive in its changing environment over time. A species will change to survive in its changing environment over time. Abiotic Factors (nonliving factors like rain or temperature changes) and Biotic Factors (living factors such as availability of prey, or new competition for food or a home) are the two sources of environmental change that will put pressure on a species. Abiotic Factors (nonliving factors like rain or temperature changes) and Biotic Factors (living factors such as availability of prey, or new competition for food or a home) are the two sources of environmental change that will put pressure on a species.

12. 12 IV. Adaptation Each time there is an environmental change, those individuals who cannot survive will die, while those who can survive, live to reproduce – this is Survival of the Fittest. Each time there is an environmental change, those individuals who cannot survive will die, while those who can survive, live to reproduce – this is Survival of the Fittest. If none of the individuals of a species has a trait that allows the species to survive, it will die out and become extinct. If none of the individuals of a species has a trait that allows the species to survive, it will die out and become extinct.

13. 13 IV. Adaptation Adaptation applies to all living things: Adaptation applies to all living things: Ex - If a colony bacteria are treated with a powerful antibiotic, all the bacteria will die except the few that are immune. The immune bacteria will reproduce, their offspring will be immune, soon the antibiotic will be useless.

14. 14 V. Mutation The source of all changes in species over time. The source of all changes in species over time. A mutation is any change in the sequence of DNA bases. A mutation is any change in the sequence of DNA bases. A mutation can be at the DNA level, the gene level, or the chromosome level. A mutation can be at the DNA level, the gene level, or the chromosome level. Since DNA codes for the amino acids which build our proteins, a change in the DNA would alter our proteins and change our traits. Since DNA codes for the amino acids which build our proteins, a change in the DNA would alter our proteins and change our traits. Mutations can be caused naturally by mistakes when DNA is copied, or by environmental factors: Mutations can be caused naturally by mistakes when DNA is copied, or by environmental factors: (Ultraviolet light, radiation, toxic chemicals, cigarette smoke, etc.) (Ultraviolet light, radiation, toxic chemicals, cigarette smoke, etc.)

15. 15 V. Mutation Depending on the environmental pressures, these changes can be positive, negative or indifferent. Depending on the environmental pressures, these changes can be positive, negative or indifferent. This status can change based on the changes in the environmental pressures (Ex: Being a long necked giraffe was not a benefit until the need arose) This status can change based on the changes in the environmental pressures (Ex: Being a long necked giraffe was not a benefit until the need arose) A mutation of the DNA in a body cell will not carry over to the next generation, but the mutation of a sex cell can be passed on to offspring. A mutation of the DNA in a body cell will not carry over to the next generation, but the mutation of a sex cell can be passed on to offspring.

16. 16 VI. Genetic Variation No two people have exactly the same DNA (except identical twins), so no two people can show the exact same traits. No two people have exactly the same DNA (except identical twins), so no two people can show the exact same traits. If a population has many individuals, all with different traits, then if the environment changes there is a better chance that someone will have the traits to survive. If a population has many individuals, all with different traits, then if the environment changes there is a better chance that someone will have the traits to survive.

17. 17 VI. Genetic Variation Ex- A very small segment of the human population is immune to HIV. If HIV spreads to infect every human, only those with the immunity would survive. Ex- A very small segment of the human population is immune to HIV. If HIV spreads to infect every human, only those with the immunity would survive. If there is more variety there is more biodiversity amongst members of a species. If there is more variety there is more biodiversity amongst members of a species.

18. 18 BIODIVERSITY Can be thought of on the ecological level as the difference between all living things Can be thought of on the ecological level as the difference between all living things Can be thought of on the evolutionary level as the difference between individuals of one species. Can be thought of on the evolutionary level as the difference between individuals of one species. Without these differences within a species, some environmental pressures may wipe out the entire species causing extinction. Without these differences within a species, some environmental pressures may wipe out the entire species causing extinction.

19. 19 VII. Gene Pool The gene pool is the sum of all the possible traits that exist in a species. The gene pool is the sum of all the possible traits that exist in a species. The larger the gene pool the more the traits, and the better chance a species has of surviving an environmental change. The larger the gene pool the more the traits, and the better chance a species has of surviving an environmental change. As the gene pool becomes larger there is more biodiversity and more genetic variation. As the gene pool becomes larger there is more biodiversity and more genetic variation.

20. 20 VII. Gene Pool As a population gets larger there will be more mutations which both cause the gene pool to grow. As a population gets larger there will be more mutations which both cause the gene pool to grow. If large numbers of a species die off or are killed the gene pool will shrink. If large numbers of a species die off or are killed the gene pool will shrink.

21. 21 VIII. Natural Selection Natural Selection is the force that drives evolution. Natural Selection is the force that drives evolution. Natural Selection states that those individuals with the best traits will produce more offspring than those with bad traits. Natural Selection states that those individuals with the best traits will produce more offspring than those with bad traits. Individuals with the best traits will out- compete other individuals for food and other resources. Individuals with the best traits will out- compete other individuals for food and other resources.

22. 22 IX. Overproduction All species produce more offspring than can survive – there are limiting factors such as food, space, competition, predators or mates. All species produce more offspring than can survive – there are limiting factors such as food, space, competition, predators or mates. Only those individuals the best at getting the resources they need will survive. Only those individuals the best at getting the resources they need will survive. Overproduction helps ensure only the best of a species will live. Overproduction helps ensure only the best of a species will live.

23. 23 X. Speciation Geographic Isolation – If a groups is separated from the rest of their species they will evolve separately. Geographic Isolation – If a groups is separated from the rest of their species they will evolve separately. Since they can no longer reproduce with others, they will evolve different traits to fit their environment. Since they can no longer reproduce with others, they will evolve different traits to fit their environment. Ex – Darwin’s Finches – each species had a different beak which was a result of the food on that island.

24. 24 The Process of Speciation The Process of Speciation A.Isolating Mechanisms 1.Behavioral Isolation 2.Geographic Isolation 3.Temporal Isolation B.Testing Natural Selection in Nature 1.Variation 2.Natural Selection 3.Rapid Evolution C.Speciation of Darwin’s Finches 1.Founders Arrive 2.Separation of Populations 3.Changes in the Gene Pool 4.Reproductive Isolation 5.Ecological Competition 6.Continued Evolution

25. 25 results from which include produced by which result in Reproductive Isolation Isolating mechanisms Behavioral isolationTemporal isolation Geographic isolation Behavioral differencesDifferent mating times Physical separation Independently evolving populations Formation of new species