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(Light or
Ermine)
This old Marans variety, which is described and recognized in the breed
Standard, has become one of the rarest varieties today, and is nearly on the
point of extinction.
Even though it has been described for a long time, this
variety has never undergone any important development, and in this respect we
have to resign ourselves to the fact there is little photographic record of it.
From the plumage aspect the phenotype of the Columbian Marans of origin is
close to that of the Light Sussex. The genotype is based
on the Wheaten eWh gene, shown by the presence of its white (or light)
under-color, it should not be like the Brahma and Wyandotte which are Brown, eb
based and have a blue/gray under-color.

The presence of the Columbian Marans white under-color in
the original Standard demonstrates the total absence of the Brown gene, eb.
We don't know if any Marans ever had
the Brown eb gene, but today this gene is not found in the genome of any Marans
variety. So the Columbian Marans genome consists of the Wheaten, eWh, allele
together with the Columbian (Co) and Silver, S. The Columbian gene restricts
the distribution of black pigment in the feathers to the hackle, tail, flights
and possibly the shank feathers. Moreover, Co also suppresses sexual dimorphism
to such an extent that the cocks and the hens have identical plumage colors.
It should be noted that these genes modify the black and white distribution on
the feathers i.e. producing a feather having a black centre with a white border
or edge, and not the opposite.
The genome of the Columbian marans cock is eWh/eWh S/S Co/Co
Id/Id Pti-1/Pti-1 and the hen eWh/eWh S/- Co/Co Id/Id Pti-1/Pti-1.
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