Elements of Evolution.doc

Elements of Evolution.doc - authorbio Richard E. Lenski,...

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author bio Richard E. Lenski, Ph.D., has written more than 100 articles on ecology,  genetics, and evolution. He is a fellow   of the American Academy of Arts  and . ..     evolution:  evolution theory Evolution: Fact and Theory By Richard E. Lenski An ActionBioscience.org original article article highlights Evolution is both fact and theory, explaining: the major patterns of change in nature how these changes occur fossil and genetic evidence of change more  on author September 2000 Evolution: Fact and Theory By Richard E. Lenski Evolution theory  explains how  organisms have  changed over  time. Scientific understanding requires both facts and theories that can explain  those facts in a coherent manner. Evolution, in this context, is both a fact and  a theory. It is an incontrovertible fact that organisms have changed, or  evolved, during the history of life on Earth. And biologists have identified and  investigated mechanisms that can explain the major patterns of change.  There are four  major patterns of  change. Patterns in Nature The field of evolutionary biology seeks to provide explanations for four  conspicuous patterns that are manifest in nature. The first three concern living  species, whereas the fourth relates to fossils.  Genes are linked  to how  organisms look  and behave. Genetic variation.  There is tremendous genetic diversity within  almost all species, including humans. No two individuals have the  same DNA sequence, with the exception of identical twins or clones.  This genetic variation contributes to phenotypic variation - that is,  diversity in the outward appearance and behavior of individuals of the  same species.  Organisms must  adapt to their  Adaptation.  Living organisms have morphological, biochemical, and  behavioral features that make them well adapted for life in the 
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environment to  survive. environments in which they are usually found. For example, consider  the hollow bones and feathers of birds that enable them to fly, or the  cryptic coloration that allows many organisms to hide from their  predators. These features may give the superficial appearance that  organisms were designed by a creator (or engineer) to live in a  particular environment. Evolutionary biology has demonstrated that  adaptations arise through selection acting on genetic variation.  Species evolved  along different  paths from a  common  ancestor. Divergence.
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This note was uploaded on 06/11/2009 for the course PSYCH 408 taught by Professor Price during the Spring '09 term at Nicholls State.

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Elements of Evolution.doc - authorbio Richard E. Lenski,...

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