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Originally Posted by navillusc  Pardon me for mentioning this, but...and I know I am not a geneticist nor a breeder of the Yorkshire Terrier...but it is my understanding that recessives only express when a homozygous gene pair exists. Otherwise, when a heterozygous pair exists, the recessive gene remains visibly 'invisible' unless it or a modifier can create a 'blended' outcome.
So, if short hair is dominant, and long hair is recessive in the Yorkshire Terrier, then wouldn't all Yorkshire Terriers with long hair be, by default, homozygous for that recessive gene pair?
If so, how exactly, without a mutation or modifier, or non-Yorkshire Terrier in the immediate parental mix, could two (2) homozygous recessive long-haired dogs produce a dominate homo-or-heterozygous short-haired dog? |
Good question! Either the breeder lied about the appearance or identity of Minnie's parents (i. e. one of them was a heterozygous short-haired Yorkie), or Minnie underwent a spontaneous mutation early in her development and acquired the dominant gene in that way (in which case she would be heterozygous). A third possibility is that Minnie's parents carry an unknown recessive gene for short hair that hasn't been widely published on. I searched the literature and didn't come across anything, but that doesn't mean that such a gene doesn't exist. That's why I encourage Minnie's breeder to stop breeding her parents.