Color Genetics in Horses

Coat Color Genetics

• Theory– Coat colors are just that, a theory. • Research on coat color and genetics is an ongoing

research as new things are developed and discovered.

Genes

• Colors are passed on to offspring through genes.

• The offspring receive genes from each of the parents, creating their own set of chromosomes.

• Cell division- Sperm and Eggs

Genes• Dominant Genes- Just that, they are dominant. This is

the gene that is going to show. Dominant is represented with a capitol letter (D).

• Recessive Genes- This gene is submissive to the the dominant gene. Recessive is represented with lower case letters (d).

• There are three possible outcomes. – Two dominant genes. Example AA– Two recessive genes. Example aa

• When there are two recessive genes, this is the color that will show.

– One dominant, one recessive. Example Aa• The dominant gene will be the color to show.

Gene Relationships

• Homozygous- referring to a gene pair that is the same.– Homozygous Dominant- gene pair with two

dominant genes (AA).– Homozygous Recessive- gene pair with two

recessive genes (aa).• Heterozygous- referring to a gene pair that has

one dominant and one recessive (Aa).

Punnett Square

• Punnett Square is a way of determining a genetic make-up. In this situation, horse color.

• Punnett Square uses both the genetic make-up of the stallion and the mare and helps us to determine the possible outcomes of the offspring.

Stallion

Mare e e

E Ee Ee

e ee ee

Stallion is Homozygous Recessive for the red gene (red based pigment) and represented with lower case letters (ee).Mare is Heterozygous with the black gene (black based pigment) being dominant and is represented with a capitol and lowercase letter (Ee)

In this situation, there is a 50% chance of the colt have black based pigment and a 50% chance of the colt having red based pigment.

Dilutions and Modifiers• These are the genes that create

colors such as Duns, Buckskins, Palominos and Gray.

• Gray is a dominant gene. Gray can affect any color both red and black pigmented colors. Gray is represented (G). – Homozygous gray (GG)

• Will “gray-out”

– Homozygous Recessive (gg)• This gray will not “gray-out”

however they carry the gray gene.

– Heterozygous gray (Gg)• Will “gray-out”, though generally

not as much as a GG will.

Dilution and Modifiers Cont.

• Dun horses are represented with (D). Horses that are DD or Dd will have diluted color throughout their body but the points such as legs, ears, mane, and tail will not be affected by the dilution. A horse that is dd will NOT be a dun.

• Dun horses can be both red based or black based and represent the colors buckskin dun, red dun, or grulla.

• Dun horses are factored with base colored points and a stripe down their back known as a dorsal stripe. They may occasionally have striping in their points.– A true buckskin will NOT have a dorsal stripe.

Red Dun

Buckskin Dun

Grulla

Cream Gene• Cream is represented by (Cr)• A horse carrying CrCr will be

more diluted than a horse with an nCr (normal cream). CrCr horses are colors such as cremellos, perlinos, and smoky creams.

• nCr horses are colors such as palomino, buckskin and smoky black.

• nn (normal color) can be represented as black, sorrel, or bay.

Punnett SquarenCr X nCr

(Palomino X Palomino)

Stallion

Maren Cr

n nn nCr

Cr nCr CrCr

In this case there is 25% chance of nn (sorrel, black or bay) 25% chance of CrCr (Cremello) and 50% chance of nCr (Palomino).

References

http://www.coquatranch.com/colorpatternsgenetics.htm#283709091

http://www.equinestudiesinstitute.com/sample_genetics.htm