In this article, a biallelic reversible mutation model with directional and quadratic selection is analyzed that reconnects to an approach proposed by Kimura 20 . Kimura starts from a diffusion model and derives its equilibrium distribution up to a constant. We use a boundary-mutation Moran model, which approximates general mutation models for small effective mutation rates, and derive its equilibrium distribution for polymorphic and monomorphic variants in small to moderately sized populations. Using this model, we show that biased mutation rates and directional selection alone can cause  polymorphism rates within and substitution rates between populations that are  ascribed to balancing or overdominant selection by the McDonald-Kreitman test 26 . We illustrate this using a data set of short intronic and fourfold degenerate sites from Drosophila simulans and Drosophila melanogaster.
In this article, a biallelic reversible mutation model with linear and quadratic selection is analyzed . The approach reconnects to one proposed by Kimura ( Possibility of extensive neutral evolution under stabilizing selection with special reference to nonrandom use of codons (PNAS,1981)), who starts from a diffusion model and derives its equilibrium distribution up to a constant. We use a boundary-mutation Moran model, which approximates a general mutation model for small effective mutation rates, and derive its equilibrium distribution for polymorphic and monomorphic variants in small to moderately sized populations. Using this model, we show that biased mutation rates and linear selection alone can cause patterns of polymorphism rates within and substitution rates between populations that are usually ascribed to balancing or overdominant selection . We illustrate this using a data set of short introns and fourfold degenerate sites from Drosophila simulans and Drosophila melanogaster.
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directional
linear
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that reconnects to an approach
. The approach reconnects to one
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20
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. Kimura
( Possibility of extensive neutral evolution under stabilizing selection with special reference to nonrandom use of codons (PNAS,1981)), who
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general mutation models
a general mutation model
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directional
linear
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patterns of
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usually
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by the McDonald-Kreitman test
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26
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intronic
introns