chap15 - Mechanisms of Evolution Chapter 15 Biological...

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Mechanisms of Evolution Chapter 15
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Biological populations change over time, or evolve . Evolutionary change is observed in laboratory experiments, in natural populations, and in the fossil record.
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Evolutionary theory —understanding the mechanisms of evolutionary change. It has many applications: study and treatment of diseases, development of crops and industrial processes, understanding the diversification of life, and how species interact. It also allows us to make predictions about the biological world.
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Theory —In everyday speech, an untested hypothesis or a guess. Evolutionary theory is not a single hypothesis, but refers to our understanding of the mechanisms that result in genetic changes in populations over time and to our use of that understanding to interpret changes in and interactions among living organisms.
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Charles Darwin was interested in geology and natural history.
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In 1831, Darwin began a 5-year voyage around the world on a Navy survey vessel, the HMS Beagle .
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The Voyage of the Beagle
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From the observations and insights made on the voyage, and new ideas from geologists on the age of the Earth, Darwin developed an explanatory theory for evolutionary change: • Species change over time. • Divergent species share a common ancestor. • The mechanism that produces change is natural selection .
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In 1858, Darwin received a paper from Alfred Russel Wallace with an explanation of natural selection nearly identical to Darwin’s. Both men are credited for the idea of natural selection. Darwin’s book, The Origin of Species , was published in 1859.
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Darwin observed artificial selection of domesticated plants and animals an used these observation to help him understand changes within a population. Darwin bred pigeons and recognized similarities between selection by breeders and selection in nature Selection on different characters in a single species of wild mustard produced many crop plants.
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Figure 15.5 Artificial Selection
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Many Vegetables from One Species
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By 1900, the fact of evolution was established, but the genetic basis of evolution was not yet understood. Then the work of Gregor Mendel was rediscovered, and during the 20 th century, work continued on the genetic basis of evolution. A “modern synthesis” of genetics and evolution took place 1936–1947.
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Milestones in the Development of Evolutionary Theory
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The structure of DNA was established by 1953 by Watson and Crick. In the 1970s, technology developed for sequencing long stretches of DNA and amino acid sequences in proteins. Evolutionary biologists now study gene structure and evolutionary change using molecular techniques.
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Mutation, Selection, Gene Flow, Genetic Drift, and Nonrandom Mating Result in Evolution Biological evolution refers to changes in the genetic makeup of populations over time. Population
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chap15 - Mechanisms of Evolution Chapter 15 Biological...

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