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What is evolution? Evolution basically means change.

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Presentation on theme: "What is evolution? Evolution basically means change."— Presentation transcript:

1 What is evolution? Evolution basically means change.
Several definitions: 1. The process by which different kinds of living organisms are thought to have developed and diversified. 2. The development of new types of organisms from preexisting types. 3. A heritable change in the characteristics within a population from one generation to the next. Have students write down and discuss the three definitions and highlight key words and ideas.

2 Are there different types?
Microevolution- changes in the gene pool of a population over time which result in relatively small changes to the organisms in the population Macroevolution- changes in organisms which are significant enough that, over time, the newer organisms would be considered an entirely new species. Have students write down the types of evolution and discuss them in terms of the definitions for evolution from the previous slide

3 What is a theory? A conclusion that draws observations, hypothesis, inferences and laws together to make sense of them a well-supported explanation for some aspect of the natural world that incorporates many observations, inferences, and tested hypothesis. Examples: Cell Theory, Theory of Gravity or Germ Theory Theories are constantly challenged and amended – Have students write down definitions given VIDEO CLIP

4 Journal Entry Tell me what you know… 1. What is a theory?
2. What is evolution? Write some ideas about both questions.

5 What is a theory? 3. A theory is _______
4. Evolution is considered a theory because _______

6 Put your ideas together…
Using the sentences you just wrote answer the following questions In your own opinion, is evolution JUST a theory?

7 Chapter 15 Theory of Evolution

8 Evolution All the changes that have formed life on earth from its earliest beginnings to the diversity that characterizes today. The heritable changes in the characteristics within a population from one generation to the next.

9 Microevolution vs. Macroevolution
Microevolution: changes within a subspecies or gene pool of a species. Small scale changes; studies changes in populations over a few generations. These changes may be due to several processes: mutation, natural selection, artificial selection, gene flow, and genetic drift.

10 Microevolution vs. Macroevolution
Macroevolution: Large-scale changes over geological era/time. a scale of analysis of evolution in separated gene pools. Studies evolution ranging from thousands to millions of years ago.

11 Geology in the 1800’s George Cuvier (1769-1875) Catastrophism-
French Anatomist Catastrophism- sudden geologic catastrophes caused the extinction of large groups of animals at certain points in the past.

12 Geology in the 1800’s Charles Lyell (1797-1875) Uniformitarianism
English Geologist Uniformitarianism Geologic processes have changed the shape of the earth’s surface in the past and continue to work in the same ways today

13 Jean Lamarck French Scientist (1744-1829)
Proposed that similar species descended from a common ancestor To explain how species changed he hypothesized that acquired traits (not inherited) could be passed on to offspring – Giraffes could stretch to reach foliage in trees and because they did, their offspring would automatically have longer necks. - FALSE

14 Jean Lamarck His hypothesis was fiercely attacked and easily disproved
But, he was the first to clearly state that types of organisms changed over time and that similar types of organisms are modified descendents of older types.

15 Charles Darwin An English Naturalist (1809-1882)
He proposed the hypothesis that species were modified by natural selection

16 Darwin

17 Charles Darwin From he was a naturalist on board the H.M.S. Beagle for a 5 year mapping and collecting expedition to South America and the South Pacific. While on board the ship he collected 100’s of specimens and fossils and kept careful records of his observations.

18 When he returned he analyzed his data over a period of 20 years and finally published his work on evolution by natural selection. He wrote a famous book which was published in 1859 called “On the Origin of Species”

19 Darwin’s Theories Descent with Modification - states that the newer forms appearing in the fossil record are actually the modified descendents of older species. (Describes the process of evolution)

20 Darwin’s Theories 2. Theory of Natural Selection -Describes the mechanism or how evolution occurs. It has five important parts: All organisms produce more offspring than can survive. “Overproduction” All organisms within a species vary. “Genetic Variation” Every organism faces a constant struggle to survive. Organisms best suited for their environment survive. “Survival of the Fittest” e) Organisms that survive pass their traits onto their offspring. Differential Reproduction

21 Darwin’s Theories **The resulting change in the genetic makeup of a population is Evolution. **In an evolving population, a single organism’s genetic contribution to the next generation is termed Fitness.

22 Who is more likely to survive?

23 Favorable Traits The environment “selects” the traits that will increase a population. The kinds of traits that are favorable depend on the demands of the environment. A favorable trait is known as an adaptation or it gives an organism an adaptive advantage. Write this in the margin Adaptation: A favorable trait that helps an organism survive.

24 Steven Jay Gould American Paleontologist and Evolutionary Biologist ( ) He developed the theory called “Punctuated Equilibrium” where evolutionary change occurs suddenly and rapidly followed by longer periods of evolutionary stability.

25 Charles Darwin

26 Who was Charles Darwin? Shoulder partners - A answer, B restate and add to the answer Charles Darwin was _________

27 Why was Charles Darwin revolutionary?
Face partners - B answer, A restate and add to the answer Charles Darwin was considered revolutionary because____________

28 What was Charles Darwin’s contribution?
Using your notes, discuss this at your table and write out one answer to share. The contribution that Charles Darwin made was ______________

29 Trading Cards When the music plays, trade cards as many times as possible. When the music stops, form a group. #1-5 and look up at the screen for more instructions

30 Evidence to support Evolution
Any evidence of life from the past FOSSILS A trace of a long-dead organism (most are hard parts such as bones, teeth, shells, and woody stems.)

31 Where are fossils found?
Sedimentary rock layers (strata) (Grand Canyon, AZ) Frozen in Ice (wooly mammoth) Stuck in tree sap or Amber (insects) Stuck in Tar (Saber Toothed Tigers)

32 Fossils are not always body parts but:
Imprints - a film of carbon remains after an organism decays Mold - an imprint or impression in a rock of the shape or track of an organism

33 Cast - when sediments or hard minerals fill in a cavity left by a fossil mold
Replacement - when sediments or hard minerals replace the whole organism. ex. petrified wood

34 Scientists Who Study Fossils…

35 The Age of Fossils Relative Age - the fossil’s age compared or related to another fossil. (because a fossil was found in a rock layer below another fossil, we could say it is older.) Absolute Age - can be estimated from the amount of sediment deposited above the fossil. (numerical age)

36 Radioactive Dating The age of fossils can be determined by measuring the amount of a particular isotope it contains. This quantity is then compared with the amount of some other substance in the fossil that remains constant over time. Carbon > Carbon 12

37 The Geologic Time Scale
A time scale for the history of the Earth

38 Geologic Time Scale Precambrian Paleozoic Mesozoic Cenozoic
4.5 bya-600 mya Paleozoic 600 mya- 225 mya Mesozoic 225 mya-2.5 mya Cenozoic 2.5mya– present

39 The Fossil Record Fossil-bearing strata show that species of organisms appear, existed for awhile, and then disappear or became extinct The fossil record indicates that there were several mass extinctions, which are brief periods during which large numbers of species disappeared e.g trilobites disappeared during the Permian extinction 245 million years ago.

40 Evidence for Evolution by Natural Selection
Eastern long neck turtle and desert turtle Common Ancestry Some species have evolved from one common ancestor Ex. finches and tortoises Show COSMOS Episode 2 clip here

41 COSMOS Episode 2 clip

42 2. Homologous Structures-
Structures that are embryologically and structurally similar, but have different functions ( SAME STRUCTURE, DIFFERENT FUNCTION) ex. human arm and bat wing

43 3. Analogous Structures-
Structures that are similar in their function, but have very different embryological development and different anatomy or structures. (DIFFERENT STRUCTURE, SAME FUNCTION) ex. Wings Insect wings and bird wing

44 4. Vestigial Structures-
Organs or structures that have no use any more ex. human tailbone, whale pelvic bone

45 5. Embryological Similarities-
Similarities in embryos can be considered evidence of common ancestry

46 6. Similarities in Macromolecules-
RNA, DNA, and proteins (amino acid sequence) from different species are very similar.

47 Patterns of Evolution Coevolution- the changes of two or more species in close association with each other ex. Predators and their prey Parasites and their host Herbivores and plants Plants and animals that Pollinate (flower and bee)

48 Coevolution Two or more species evolve together

49 Patterns of Evolution 2. Convergent Evolution - unrelated species become more and more similar as they adapt to the same kind of envirnoment. ex. sharks and dolphins

50 Convergent Two or more species become more similar

51 Patterns of Evolution 3. Divergent Evolution- two or more related populations or species become more and more dissimilar; usually occurs as a response to differing habitats.

52 Divergent Two or more species become more dissimilar

53 Divergent Evolution Adaptive Radiation- many related species evolve from a single ancestral species. (finches – common ancestory) Artificial Selection- breeding of organisms by humans. (dogs)

54 Industrial Melanism During the 1850’s in England there was a species of moth during the time of the industrial revolution – dark moths became more common During the period when the number of coal-burning factories in England was increasing (during the Industrial Revolution) it was noticed that the number of melanic individuals of the species of Peppered Moth (Biston betularia) was becoming more common. Originally rare in the population of normally light-colored moths, the frequency of the melanic form increased in polluted areas until it was over 90%. This change in color has come to be known as "industrial melanism." The change was presumed to be a result of natural selection since the melanic moths in polluted areas better matched the blackened tree trunks where they rested during the day. In unpolluted forests distant from industrial centers the tree trunks were not blackened and the lighter colored moths were present in higher frequencies. We know that the difference between the two forms of moth is controlled by a pair of alleles at a single chromosome locus. Hint: the line that forms the boundary of the grey shaded area shows the smoke level, units for which (micrograms per cubic meter) are indicated on the right side of the graph. The line dropping through the white area shows the number of melanic moths as a percentage of the moth population. Source:

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