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Evolution explained in this solution

1. Natural selection is not only known mechanism which drives evolution. Other mechanisms include genetic drift, sexual selection, artificial selection, group selection (inclusive fitness) and the neutral theory. Briefly explain how each of these "alternate" evolutionary mechanisms functions.

2. A variety of mechanisms have been proposed to describe how speciation can occur. The two most important mechanisms are undoubtedly allopatric and sumpatric speciation. How do these two processes work to produce new species?

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What is Evolution?
Darwin described evolution as "descent with modification": the change in a lineage of populations between generations.
Functioning of different evolutionary mechanisms:

a.) Genetic Drift

The frequency of alleles with the same fitness may change at random through time in a process called genetic drift.
Genetic drift functions with the change in frequency of alleles within a population leading to variance and thus evolution.
If there are two alleles at a locus, and they have the same fitness, random sampling ...