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Chapters 14-18

Chapters 14-18 - Chapter 14 Principles of Evolution What is...

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Chapter 14 Principles of Evolution What is Evolution? Evolution Change in the proportion of genotypes in a population over time o With time measured in generations Decent of modern organisms with modifications from preexisting organisms Misconceptions About Science and Evolution 1. Scientists PROVE things 2. Evolution is “just a theory” 3. Science vs. Religion 4. “Intelligent Design” is a scientific theory Scientific Assumptions 1. All events can be attributed to natural causes a. Explanations don’t invoke supernatural causes b. Creationism; Intelligent Design 2. Natural laws apply at all places and at all times 3. People perceive events in similar ways Exploration of new lands = staggering number of species Similarities among species led to thoughts that they could change Similar species are descended from a common ancestor Fossil discoveries showed that life had changed over time Cuvier - catastrophism o Catastrophes caused extinct species & strata o Where were fossils of species that are around today? Agassiz - new creations o 50 different creations? LeClerc o Creation of small number of organisms which evolved over time o Old Testament said Earth 4000-6000 years old, not enough time Geologists showed that the Earth is old Hutton and Lyell o Uniformitarianism – slow natural forces (wind, water, earthquakes, volcanoes) caused stratification of rock Observations of geological formations + rates processes occur = Earth at least millions of year old Plenty of time for evolution, but still need a mechanism Pre-Darwinian Theory of Evolution Lamarck - Inheritance of acquired characteristics o Bodies of living organisms are modified through the use or disuse of parts o These modifications are inherited by offspring o This idea turned out to be wrong Evolution by Natural Selection Darwin and Wallace o Developed the theory independently o Darwin – voyage of the Beagle o Wallace – naturalist in Indonesia Darwin’s Finches See Figure 14-4
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How Does Natural Selection Work? Natural Selection o The unequal survival and reproduction of organisms due to environmental forces resulting in the preservation of favorable adaptations o Process “selects” from what is available in the gene pool o New genes are not created on demand Mechanism Behind Natural Selection See Figure 14-5 How do we know that evolution has occurred? Models of the origins of modern organisms 1. Static Model 2. Transformation 3. Separate types 4. Common descent Fossils of Extinct Organisms Fossils often found in sedimentary rock Rocks laid down by the deposition of sediments o Deepest strata = oldest o Shallow strata = younger Fossils from deeper strata differ from modern organisms Anatomy Homologous structures (See Figure 14-7) o May differ in function, but have similar anatomy Analogous structures o Have similar functions and superficially similar appearance, but different anatomies Vestigial structures (See Figure 14-8) o
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