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Basic Color Genetics Primer...
The following pages are a very basic introduction to shetland colors and patterns. It has been designed with the beginner in mind. Only the more common patterns seen in North America are shown.
   Terms tend to differ by region and personal opinion. I hope you will find this information easy to understand and useful. 

   When following discussions about shetland color genetics, one will commonly come across a color "genotype" and wonder what it means. I will show you an example:
     Note: A locus is just a "location" or site, of a certain gene, in this case, a color gene, on the chromosome that controls color.


     


  


"A" locus

Aa/Aa
"B" locus

Bb/Bb
"S" locus

Ss/Ss
"M" locus

Mm/Mm
The A locus is where pattern genes are located.
See below for the different patterns.		 The B locus is where the base color, either black or brown, is located.
The S locus is where the spotting genes are located. The M locus is where the modified genes are located.
The beginning two letters are the phenotype, which is the color gene that has been expressed. The phenotype is what color the sheep looks like.
The second set of letters are the genotype, the recessive color gene that may or may not influence the color on the surface.
   A sheep inherits one color gene from each parent, for a total of two at each locus. One gene can be dominant to another gene, making it more likely to express, or the gene may be have incomplete dominance, where both genes express at the same time.
    If the lamb inherits the same color genes from each parent, then the lamb is homozygous for that color. If the lamb inherits two different color genes, one from each parent, then the lamb is heterozygous for that color.  
  
Patterns at the A locus are as follows, listed from dominant to recessive:
Click on each for photos and more info.		 Click here to see shetland colors.
Includes pheomelanin and breakthrough base color.
Awt-    White
Ag-   Agouti (fading gene)
Ab-  katmoget
At-  gulmoget
Aa-  self color