Polyploidy and Hybridization

Polyploidy and Hybridization - Punctuated Equilibrium...

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Polyploidy and Hybridization Polyploidy and hybridization are important speciation mechanisms in plants. Whereas animals tend to be unisexual, plants often have both sexes functional in the same individual. Consequently, plants can (if they lack a self-incompatability mechanism) reproduce with themselves (both sexually and asexually), establishing a reproductively isolated species very rapidly. The Pace of Evolution The pace of evolution is often slow, so slow that all of the stages in species formation cannot be observed. The traditional, or Darwinian, view of evolution was that it was a very slow process, resulting from the gradual accumulation of small differences. Recently, several alternative views on the pace and events in species formation have been proposed. These are collectively called quantum speciation.
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Unformatted text preview: Punctuated Equilibrium According to another model based on the fossil record, speciation occurs rapidly over a short time, followed by a long period of little or no change. "Short" means thousands or hundreds of thousands of years. This differs greatly from Darwin's original view of slow and gradual change continuing over very long periods of time. Evidence for Evolution Evolution, which started out as a hypothesis, is now supported by evidence from many fields of science. Fossils: Evidence of Past Life The fossil record is the history of life recorded by remains from the past. Fossils include skeletons, shells, seeds, insects trapped in amber, dung, DNA and other chemicals, imprints of leaves, and tracks of organisms that lived in the distant past. Most fossils are at least 10,000 years old....
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Polyploidy and Hybridization - Punctuated Equilibrium...

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