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Published byKristina Owen Modified over 8 years ago
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{ Evidence for Evolution Part 1 Fossil records, zoogeographical maps, DNA sequences, homologous, analogous. Warm-up Questions: Which scientist coined the theory of evolution while studying finches? ________________ is the term used for when natural selection leads to the creation of a new species. Charles Darwin Speciation
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There are several places we can see evidence of evolution/evolutionary relationships: -fossils, -comparative anatomy, - biochemistry/DNA, -embryology, - and biogeography. Evidence of Change Over Time
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Fossils are evidence of organisms that lived long ago that are preserved in Earth’s rocks. TYPES OF FOSSILS Fossils TypesFormation Trace fossils Casts Molds Petrified fossils Amber-Preserved or frozen fossils A trace fossil is any indirect evidence left by an animal and may include a footprint, a trail, or a burrow. When minerals in rocks fill a space left by a decayed organism, they make a replica, or cast, of the organism. A mold forms when an organism is buried in sediment and then decays, leaving an empty space. Petrified-minerals sometimes penetrate and replace the hard parts of an organism At times, an entire organism was quickly trapped in ice or tree sap that hardened into amber.
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Scientists who study ancient life by using fossils to understand events that happened long ago. Paleontologist: They use fossils to determine the kinds of organisms that lived during the past and sometimes to learn about their behavior.
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For fossils to form, organisms usually have to be buried in mud, sand, or clay soon after they die. Fossils are not usually found in other types of rock due to the ways those rocks form. Example: the conditions under which metamorphic rocks form often destroy any fossils that were in the original sedimentary rock. Fossil Formation:
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Few organisms become fossilized because, without burial, bacteria and fungi immediately decompose their dead bodies. Occasionally, however, organisms do become fossils in a process that usually takes many years. Fossil Formation Contd. How fossils form
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Scientist use several methods for determining the age of a fossil. This method indicates that the fossils found closer to the surface, in an undisturbed ground, are younger, and the fossils found in deeper strata are older. This method only gives a relative age between the fossils and not a specific age of the fossils. Relative Dating:
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Relative Dating Contd. Using this principle, scientists can determine relative age and the order of appearance of the species that are preserved as fossils in the layers.
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There are two types, homologous and analogous. Anatomical Evidence:
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Structural features with a common evolutionary origin Science sees structural similarities as evidence that organisms evolved from a common ancestor. Homologous parts are similar in structure, but may be very different in specific function. Homologous Structures:
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The body parts of organisms that do not have a common evolutionary origin but are similar in function. Analogous parts are very different in structure, but perform similar functions. Analogous Structures:
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A body structure in a present-day organism that no longer serves its original purpose, but was probably useful to an ancestor. Vestigial Structure: Video
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Scientists believe that the fact that ALL LIVING THINGS have A,T,C, and G in their DNA and all use the same coding for proteins means we are all related in some way. Biochemical Relationships:
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The study of how similar embryos are for different organisms (may be evidence of relation) Embryology:
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Scientists believe the shared features in the young embryos of different species suggest evolution from a distant, common ancestor. Embryology Contd. Fish ReptileBirdMammal Pharyngeal pouches Pharyngeal pouches Tail
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ChickenTurtle Rat
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