One article that I found useful on this topic is "Thinking about genetic
redundancy" by James H. Thomas. Trends in Genetics 9(11):395 - 1993.
Estelle M. Hrabak
Dept. of Plant Biology
University of New Hampshire
On Sun, 22 Sep 1996, Francois Coulier wrote:
>> I am working on a gene family encoding growth factors (the FGF family).
> Several mouse genes have already been knocked out. While one of the KO
> lead to very severe phenotype (embryonic lethal, due to lack of
> implantation), most ko's lead to very mild to no detectable phenotypes. By
> mild phenotype, I mean for example the angora phenotype associated with KO
> of FGF5.
> In addition, in most cases the tissues involved in the observed phenotypes
> are only one (and minor, in term of RNA level for example) site where
> expression of the gene has been observed. For example, FGF5 is highly
> expressed in the blastocyst, and the only observed phenotype is long hair.
> To explain this, one called for redundancy between genes of the family,
> that is other FGF genes expressed in the same tissues and at the same time
> as the knocked out gene, are able to rescue its function. For example,
> other FGFs are expressed at the blastocyst stage, and may replace FGF5.
> I believe this redundancy scheme has been call for in the case of other
> multigene families.
>> The question I have is how such redundancy scheme, if real, can be
> selected for.
> If one assumes the gene is indeed dispensable, should'nt have it been lost
> during evolution (or not kept at all in the first place)?
> If one assumes the mild or undetected phenotypes are such in laboratory
> conditions only, and strongly selected against in the wild (for example
> long hairs may favour parasites), why will redundancy at, say, the
> blastocyst stage, be selected for?
>> Any comment on this redundancy scheme will be highly appreciated! Thanks
> to all of you.
>>> Francois Coulier
> INSERM Unite 119
> 27 bd Lei Roure
> 13009 Marseille
>> tel (33) 91 75 84 11 (October 18, 1996=> 33 (0) 4 91 75 84 11)
> fax (33) 91 26 03 64 (October 18, 1996=> 33 (0) 4 91 26 03 64)
> email: coulier at infobiogen.fr>>>