3rd litter born today- 25 big healthy babies

[chris-uk]

You wouldn't necessarily have to test any of the nonviable pairings - just check the parents vs. the living offspring and see if the ratios line up i.e. if Yy x Yy doesn't ever produce yy, there's something wrong with the yy pairing.

Yes with a large enough sample you could just test the living and identify whether there are any yy individuals with a statistical confidence.

Some lethal gene pairings are lethal from the start so you'd never see anything from them. In that situation, humans tend to spontaneously abort so early that the woman never even knows about it. I'm not sure how it works in herps but I would suspect it's something similar, possibly a very small ovum excreted with normal digestive waste.

I don't know how the mechanism for this works in herps either. I'd assume either expelled shortly after conception, or retained and expelled during the birth.

It's possible a lethal gene could be located near the gene in question and so they tend to travel together... but to tease that out using mendelian methods could require a tremendous sample size.

I think it could be a case of missing genetic material. In that a axanthic mutation has some vital genetic material from a nearby loci missing, this would explain why you don't get yy and also why a axanthic phenotype is only displayed when paired with an anerythristic gene - the anery expression is "weak" enough that the axanthic can dominate, but the anery genes aren't missing the genetic material that the axanthic gene does so the combination is viable.

Sorry for diverting your new litter thread Jeff. The genetics are quite interesting with this one.