1. The B gene (Black pigment gene):
* B (Black): This allele produces black pigment.
* b (Brown): This allele produces brown pigment.
2. The E gene (Extension gene):
* E (Extension): This allele allows the black or brown pigment to be fully expressed, resulting in a solid black or brown coat.
* e (Restriction): This allele restricts the expression of black or brown pigment, resulting in yellow or cream coat colors.
Here's how these genes combine to determine the puppy's color:
Black Lab:
* BBEE or BbEE: Both genes have the dominant alleles for black pigment and full expression.
* BBEe or BbEe: One gene has the dominant allele for black pigment and full expression, while the other has the recessive allele for restricted expression.
Brown Lab:
* bbEE or bbEe: Both genes have the recessive allele for brown pigment and the dominant allele for full expression.
Yellow Lab:
* BBee or Bbee: Both genes have the dominant allele for black pigment but the recessive allele for restricted expression.
* bbee: Both genes have the recessive alleles for brown pigment and restricted expression.
Understanding the different color combinations:
* Two black labs: Can produce black, brown, or yellow puppies.
* Two brown labs: Can only produce brown puppies.
* Two yellow labs: Can produce black, brown, or yellow puppies (depending on the hidden alleles).
* Black lab and brown lab: Can produce black or brown puppies.
* Black lab and yellow lab: Can produce black, brown, or yellow puppies.
* Brown lab and yellow lab: Can produce brown or yellow puppies.
Important note:
* The color of a Labrador Retriever puppy is determined by the genes inherited from both parents.
* Even if both parents are yellow, they can still carry the genes for black or brown pigment, which could be expressed in their offspring.
* Coat color does not affect the temperament or health of a Labrador Retriever.
For a more detailed understanding of Labrador Retriever genetics, you can consult with a veterinarian or a professional breeder.