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Unformatted text preview: Chap 16 Evolution Jean Baptiste de Lamarck First scientist to propose that organisms undergo change over time as a result of some natural phenomenon rather than divine intervention Thought organisms could pass traits acquired during their lifetimes to their offspring The Puzzle of Life's Diversity This variety of living things is called biological diversity. How did all these different organisms arise? How are they related? They Evolved! Evolution , or change over time, is the process by which modern organisms have descended from ancient organisms. A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world. Evolution is a change in allele frequency over time Evolution is a population level process frequency in a population Charles Darwin Theory of evolution based on his observations while voyaging on HMS Beagle Tried to explain similarities between animals and plants of arid Galpagos Islands and humid South American mainland Natural selection rests on three indisputable facts: Organisms produce more offspring than can survive. Individuals vary in their characteristics. Many characteristics are inherited by offspring from their parents. Adaptation: Any trait that increases fitness Selection acts on traits that increase fitness--allows organisms to adapt NATURAL SELECTION Mechanism of evolution in which individuals with inherited characteristics well suited to the environment leave more offspring than do individuals that are less suited to the environment Darwins Premises of Evolution by Natural Selection (1) Overproduction: Each species produces more offspring than will survive to maturity (2) Inherited variation: Individuals in a population exhibit inheritable variation in their traits (3) Limits on population growth: Organisms compete with one another for food, space, water, light, other resources needed for life (4) Differential reproductive success: Offspring with the most favorable combination of characteristics are most likely to survive and reproduce, passing those genetic characteristics to the next generation Descent with Modification Over large amounts of time natural selection produces organisms: with different structures establishes different niches occupies different habitats organisms look different than their ancestors Descent with modification = each living thing has descended with changes, from other species over time. Natural Selection Results from NO human intervention, control, or direction Results in changes in the inherited characteristics of a population Increases a species fitness in the environment (over time!) Sexual Selection Mate Choice maximize reproductive potential Strength Territory Ornaments Etc....
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This note was uploaded on 01/17/2012 for the course NSC 461 taught by Professor Benning during the Fall '11 term at Michigan State University.
- Fall '11