Presentation on theme: "Patterns of Change over Time"— Presentation transcript:
1Patterns of Change over Time Evolution:Patterns of Change over Time
2BIOLOGY STANDARDSB5. Students will evaluate the role of natural selection in the development of the theory of evolution.Relate natural selection to changes in organisms.
3EVOLUTIONEvolution is the theory that organisms change over time, a process by which modern organisms have descended from ancient organisms.
4GENETIC VARIATION Evolution is caused by genetic variation. Genetic variation comes from changes in DNA, which can be caused by:
5Crossing over (occurs during Prophase I of meiosis I) The random assortment of genes (during meiosis II)Mutations (in genes and chromosomes)Artificial selectionNatural selection
6ARTIFICIAL SELECTIONArtificial selection takes place with human control or direction.Examples of artificial selectionSelective breedingGenetic engineering
7EXAMPLE OF ARTIFICIAL SELECTION Broccoli, cabbage, kale, cauliflower, and kohlrabi are common vegetables that were cultivated from forms of wild mustard.This is evolution through artificial selection.
13LAMARCK: USE AND DISUSE Any organ that is used more will grow larger & strongerAreas that are used less will become smaller & weaker
14LARMARCK: INHERITANCE OF ACQUIRED TRAITS Any characteristic an organism possesses will be passed on to its offspring.For example:Giraffes have long necks because they had to reach the
15food in trees this caused their necks to become largeraccording to use and disuse.Giraffes with long necks then passed on these long necks to their offspring according to transmission of acquired characteristics.
16Lamarck believed that the long necks of giraffes evolved as generations of giraffes reached for ever higher leaves.
18DARWIN’S THEORY OF EVOLUTION The theory of evolution was proposed by Charles Darwin after observing the plants, animals, and fossils of the Galapagos Islands.Darwin noticed that species varied from island to island.
20ACTIVITIES “Graphing Bird Adaptations” “Comparing Adaptations of Birds”
21SUMMARY OF DARWIN’S THEORY Individual organisms in nature differ from one another. Some of this variation is inherited.Organisms in nature produce more offspring than can survive, and many of those that survive do not reproduce.
22Because more organisms are produced than can survive, members of each species must compete for limited resources.Because each organism is unique, each has different advantages and disadvantages in the struggle for existence.
23Individuals best suited for their environment survive and reproduce most successfully. The characteristics that make them best suited to their environment are passed on to offspring. Individuals whose characteristics are not as well suited to their environment die or leave fewer offspring.
24Species change over time Species change over time. Over long periods, natural selection causes changes in the characteristics of a species, such as in size and form. New species arise, and other species disappear.
25Species alive today have descended with modifications from species that lived in the past. All organisms on Earth are united into a single tree of life by common descent.
27HOMOLOGOUS STRUCTURES structures which have different mature forms but develop from the same embryonic tissue
28ANALOGOUS STRUCTURESstructures which look and function similarly but do not share the same evolutionary history
29Bat wings and bird wings are analogous as flight structures: their structure and function have evolved by different routes from a flightless reptilian ancestor.
30Note that a good portion of the flight surface in bats consists of a membrane stretched between the extended bones, whereas the bones of the bird are relatively small and do not support the flight surface.
31MICROEVOLUTION Evolution that occurs within the species level Microevolution results in the creation of new species.New species evolve as populations become reproductively isolated from each other
33SPECIATIONThe development of one or more species from an existing species.Historical example of speciationDarwin’s finchesCurrent example of speciationDiane Dodd’s fruit fly experiment
34SPECIATION CONT’DDiane Dodd’s fruit fly experiment suggests that isolating populations in different environments (e.g., with different food sources) can lead to the beginning of reproductive isolation. These results are consistent with the idea that geographic isolation is an important step of some speciation events.
36MACROEVOLUTIONlarge scale evolutionary changes that take place over long periods of time; evolution between different species
37Macroevolution can be represented by the evolutionary tree.
38BIOLOGY STANDARDSB5. Students will evaluate the role of natural selection in the development of the theory of evolution.Trace the history of the theory.Explain the history of life in terms of biodiversity, ancestry, and the rates of evolution.Explain how fossil and biochemical evidence support the theory.
40FOSSILSFossils are the mineralized remains of animals or plants or other artifacts such as footprints.The totality of fossils and their placement in rock formations and sedimentary layers (strata) is known as the fossil record.
41The fossil record provides evidence about the history of life on Earth The fossil record provides evidence about the history of life on Earth. It also shows how different groups of organisms have changed over time.The fossil record reveals that fossils occur in a particular order: some only in older rock and some only in more recent rock.The study of fossils is called paleontology.
42DATING FOSSILSRelative dating allows paleontologists to estimate a fossil’s age compared with that of other fossils.In radioactive dating, scientists calculate the age of a sample based on the amount of
43remaining radioactive isotopes it contains. Scientists use the half-life of radioactive isotopes to date fossils.
44HALF-LIFEA half-life is the length of time required for half the radioactive atoms in a sample to decay.
45Radioactive isotope with a short half-life: carbon-14 (5730 years) Used to date younger fossilsRadioactive isotope with a long half-life: potassium-40 (60,000 years)Used to date older fossils
46GEOLOGIC TIME SCALEIn the geologic time scale, time is divided the eon, era, period, and epoch.
47Remember that macroevolution is the large scale evolutionary change that takes place over long periods of time.The events of macroevolution are reflected in the geologic time scale.
48EVOLUTION OF LIFEEarly Earth was hot; atmosphere contained poisonous gases.Earth cooled and oceans condensed.Simple organic molecules may have formed in the oceans.
49Small sequences of RNA may have formed and replicated. First prokaryotes may have formed when RNA or DNA was enclosed in microspheres.Later prokaryotes were photosynthetic and produced oxygen.
50An oxygenated atmosphere capped by the ozone layer protected Earth. First eukaryotes may have been communities of prokaryotes. (endosymbiosis)Multicellular eukaryotes evolved.Sexual reproduction increased genetic variability, hastening evolution.
51The Atmosphere of Early Earth Earth’s early atmosphere probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and water.Thunderstorms predominated.Primitive oceans were brown from dissolved iron deposits.
52Could organic molecules have evolved under the conditions of early Earth? In the 1950s, Stanley Miller and Harold Urey tried to answer this question.
53A flask was filled with hydrogen, methane, ammonia, and water to represent the conditions of early Earth.
54The flask was sealed to eliminate the possibility of contamination by microorganisms (bacteria, viruses, and fungi).
55Electric sparks were passed through the mixture to simulate the lightning strikes of the early atmosphere.
56Over a few days, several amino acids (the building blocks for proteins) began to accumulate. Miller and Urey’s experiments suggested how mixtures of organic compounds could have arisen from simpler compounds present in early Earth.
57Later experiments found that the Miller/Urey simulation was not accurate. However, similar experiments based on current knowledge of Earth’s early atmosphere have also produced organic compounds.
58BIOLOGY STANDARDSB5. Students will evaluate the role of natural selection in the development of the theory of evolution.Explain the history of life in terms of biodiversity, ancestry, and the rates of evolution.Explain how fossil and biochemical evidence support the theory.
63Reading a Geologic Time Scale ACTIVITYReading a Geologic Time Scale
64The Mass Extinction of the Dinosaurs: The Asteroid-Impact Hypothesis
65Luis and Walter Alvarez Luis, along with his son Walter, proposed the asteroid-impact hypothesis.
66At the end of the Cretaceous period, the dinosaurs, along with many species of aquatic and terrestrial organisms, became extinct.In 1980, Luis Alvarez, along with his son Walter, proposed the asteroid-impact hypothesis.
67The asteroid-impact hypothesis suggests that a huge asteroid hit the Earth, sending so much dust into the atmosphere.This dust blocked the sun, which caused a change in the Earth’s climate.This change in climate led to the mass extinction.
68Alvarez and Alvarez noted that sediments from the end of the Cretaceous period contained high concentrations of iridium.Iridium is rare in the Earth’s crust, but it is abundant in asteroids and other extraterrestrial bodies.Quartz crystals, deformed by a powerful force, were also found in sediments of this time period.
69Further evidence for this hypothesis was provided by the possible site of impact, the Chicxulub crater located on the Yucatan Peninsula in southern Mexico.The crater dates from the end of the Cretaceous period and is (180 km) 110 miles across.
71ADAPTIVE RADIATIONA single species or a small group of species has evolved into several different forms that live in different ways.ExamplesDarwin’s finchesThe extinction of dinosaurs cleared the way for the adaptive radiation of many species of mammals.
72Figure legend: Adaptive Radiation Figure legend: Adaptive Radiation. New groups come from a common ancestor. These new groups are suddenly able to exploit new habitats. If these groups eventually become reproductively isolated, they may become new species.
73The process by which unrelated organisms come to resemble each other. CONVERGENT EVOLUTIONThe process by which unrelated organisms come to resemble each other.
74PUNCTUATED EQUILIBRIUM After long stable periods (equilibrium), new species are produced by shorter periods of rapid change.Evolution is believed to occur at different rates for different organisms at different times.
79BIOLOGY STANDARDSB5. Students will evaluate the role of natural selection in the development of the theory of evolution.Recognize the role of evolution to biological resistance (pesticide and antibiotic resistance).