A chief difficulty in arguing for macroevolution by mutations is the fact that most expressed mutations are either lethal or semi-lethal. |
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Pokey, a sex-linked recessive semi-lethal gene in Tribolium castaneum has been described. |
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Some of the genes that gives the mouse its common colours or markings also makes the mouse sick, or unfit to live. These genes are called semi-lethal or lethal. |
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