Colour Coding!

Definitions

Allele: Variant form of a gene. Alleles come in pairs in all cells EXCEPT gametes (eggs and sperm), which contain alleles singly. An ovum will contain one half of an allele pair, which will combine with the alleles in a sperm cell to form the full genetic code of the offspring at conception. This is why, genetically, every offspring is 50% sire and 50% dam.

Dominant: An allele which is capable of masking the effect of a recessive allele. In this case, dominance will be indicated with an upper-case letter.

Genotype: The genetic makeup, or blueprint, of an organism.

Homozygous: Both alleles at the specific location are the same. This means a homozygous animal will pass on that allele in 100% of its eggs or sperm.

Heterozygous: Both alleles at the specific location are different. This means a heterozygous animal will pass on each of its alleles 50% of the time.

Phenotype: The outward appearance of an organism.

Recessive: An allele which will only be expressed in the absence of a dominant allele. In this case, a recessive allele will be noted with a lower-case letter.

Links

Animal Genetics, Inc. Coat Color Calculator: http://www.animalgenetics.us/CCalculator1.asp

U.C. Davis Veterinary Genetics Laboratory: http://www.vgl.ucdavis.edu/services/horse.php

Householder, D., The Genetics of Equine Coat Color: http://animalscience.tamu.edu/images/pdf/equine/equine-genetics-equine-coat-color.pdf

Introduction to Mendelian Genetics: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookgenintro.html

The Appaloosa Project: http://www.appaloosaproject.info

photos shown in slideshow below

Photo 1: Courtesy of Ashbank Equestrian; dam: EEAaTT, foal: EeAATt

Photo 2: Courtesy of Aloris Miniature Horses; Banner Shadows Moon Cruiser: eeCRCR

Photo 3: Courtesy of Lynaire Sports Horses; Legrande: EeACRcr

Photo 4: Courtesy of Aloris Miniature Horses; Misthaven Arrows High: eeT with SB1 and Z (sabino and silver dapple present)

Photo 5: Courtesy of OFS Horses; The Cullinan Diamond: EAGg

Photo 6: Courtesy of OFS Horses; Ballykett Blue Diamond: EAG, OFS Amiro Blue: EeAGg

Photo 7: Courtesy of OFS Horses; Hobgoblins Late Night: EeA

Photo 8: Courtesy of Ashlan Stud; Ashlan Dreamsong: eeTt

Photo 9: Courtesy of Ashlan Stud; Ashlan Libretto: EeATt