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Current Competing Theories of the Origin of Life on Earth: It Arrived from an Extraterrestrial Source; It Originated as a Heterotrophy; It Originated as an Autotrophy.

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Submitted By passipeiris
Words 848
Pages 4
Genetic diversity is always changing both across space and through time. Typically, the amount and type of genetic diversity within a species vary across its natural range. Additionally, its genetic diversity changes over time. At least in the long-term, and sometimes even over shorter time frames such as a few generations of the species. These natural changes in the genetic diversity of a species create a dynamic landscape upon which any influences that we exert are superimposed. To better understand our impacts, and to decide if management actions are warranted, it is useful to understand the natural dynamics of genetic diversity. Genetic diversity is affected by several ongoing natural processes. These processes are: mutation, migration, genetic drift, and selection.

Mutation is the origin of all new genetic diversity, occurring when there are occasional errors in the replication of DNA or other elements of the production and packaging of genetic information within the cells. Although implies something negative, mutations can have positive, neutral, or deleterious impacts Mutations occur rather slowly but continuously. Mutations at one level, for example, in the nucleotides that are the basis of DNA, May not all is expressed at other levels — such as protein differences or observable changes in the appearance of a plant. The rate of mutation is useful in determining evolutionary relationships.
Mutations can be beneficial, neutral, or harmful for the organism, but mutations do not "try" to supply what the organism "needs." Factors in the environment may influence the rate of mutation but are not generally thought to influence the direction of mutation. For example, exposure to harmful chemicals may increase the mutation rate, but will not cause more mutations that make the organism resistant to those chemicals. In this respect, mutations are random whether a

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