>i was thinking today about if co-dom visable morphs could be latent(not-visable) given certain circumstances.

Yes, indeed. There are two possible answers to this:

1. The genetic principle of epistasis, in which a mutant gene at one location in the genome masks the expression of a mutant gene at another location in the genome. For example, in mice, the albino mutant gene (a recessive mutant) can prevent the expression of the sombre mutant gene (a dominant mutant), which produces a nearly black mouse. An albino sombre mouse has the sombre gene and can pass it on to the offspring. But such a mouse looks just like an albino mouse that is normal at the sombre mutant's location in the genome.

Inheritance pattern of the mutants has nothing to do with epistasis. In other words, depending of what the mutants do, a dominant mutant can mask the presence of a dominant mutant, a codominant mutant or a recessive mutant. Or a codominant mutant can mask the presence of a dominant mutant, a codominant mutant or a recessive mutant. Or a recessive mutant can mask the presence of a dominant mutant, a codominant mutant or a recessive mutant.

2. The genetic principle of incomplete penetrance. In this, because of other genes or environmental factors, a dominant mutant simply is not physically manifested. For example, in a percentage of humans with the polydactyl (extra fingers) mutant gene, the person just has five fingers on each hand and five toes on each foot. Yet this person's children who inherit the mutant have six fingers/toes.

For both principles, the biochemistry has to be worked out individually for every example. And in most cases, the biochemistry has yet to be worked out, as far as I know.

Hope this helps.

Paul Hollander

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