Blackwell Publishing

Molecular evolution and neutral theory - Why are Kimura's arguments flawed?


Kimura's case against natural selection

Kimura's argument was that neutral drift can explain the high rate of molecular evolution and high levels of polymorphism, whereas natural selection cannot. But his case against natural selection made assumptions about genetic loads that are unrealistic for the following reasons:

1. There is a distinction between hard and soft selection. Proponents of the neutral theory have assumed that selection is too hard.

2. Natural selection can act jointly on many genetic loci. Kimura assumed that selection operates independently at each locus.

3. Frequency-dependent selection can maintain polymorphism.

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