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 populationMacroevolution- 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 thema 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 TheoryTheories are constantly challenged and amended –Have students write down definitions givenVIDEO 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 questionsIn your own opinion, is evolution JUST a theory?
8 EvolutionAll 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 AnatomistCatastrophism-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 GeologistUniformitarianismGeologic 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 ancestorTo 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
17 Charles DarwinFrom 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 TheoriesDescent 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.
23 Favorable TraitsThe 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 marginAdaptation: A favorable trait that helps an organism survive.
24 Steven Jay GouldAmerican 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.
35 The Age of FossilsRelative 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 DatingThe 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
39 The Fossil RecordFossil-bearing strata show that species of organisms appear, existed for awhile, and then disappear or became extinctThe fossil record indicates that there were several mass extinctions, which are brief periods during which large numbers of species disappearede.g trilobites disappeared during the Permian extinction 245 million years ago.
40 Evidence for Evolution by Natural Selection Eastern long neck turtle and desert turtleCommon AncestrySome species have evolvedfrom one common ancestorEx. finches and tortoisesShow COSMOS Episode 2 clip here
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. WingsInsect wings and bird wing
44 4. Vestigial Structures- Organs or structures that have no use any moreex. 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 EvolutionCoevolution- the changes of two or more species in close association with each otherex. Predators and their preyParasites and their hostHerbivores and plantsPlants and animals thatPollinate (flower and bee)
49 Patterns of Evolution2. Convergent Evolution - unrelated species become more and more similar as they adapt to the same kind of envirnoment.ex. sharks and dolphins
50 ConvergentTwo or more species become more similar
51 Patterns of Evolution3. Divergent Evolution- two or more related populations or species become more and more dissimilar; usually occurs as a response to differing habitats.
52 DivergentTwo or more species become more dissimilar
53 Divergent EvolutionAdaptive Radiation- many related species evolve from a single ancestral species. (finches – common ancestory)Artificial Selection- breeding of organisms by humans. (dogs)
54 Industrial MelanismDuring the 1850’s in England there was a species of moth during the time of the industrial revolution – dark moths became more commonDuring 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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