In addition to the possibility of one morph completely covering another (for example how would you see the stripe in a striped leucistic) there are a couple of other possibilities that we might run into eventually also.



One is that two morphs might turn out to be alleles - different mutations of the same gene. This might actually be a pleasant surprise. When someone goes to cross say albino and caramel if it turns out that they are different mutations of the same gene then neither parent will have a normal copy of that gene so the babies can't be normal. It's hard to know what they might look like though, maybe albino, maybe caramel, maybe half way in-between or something different. This is just an example and with the large number of genes we may not find any allele morphs any time soon but a possibility that one should consider, especially with mutations that seem to have some of the same characteristics.



Another possibility is that two mutations might be linked in that they are different mutations of different genes on the same chromosome. In this situation the babies from the initial homozygous X homozygous cross are normal looking double hets as expected however it becomes harder than the expected 1 in 16 to make the double homozygous in the next generation. This is because when each double het parent is making their copy of that chromosome for the offspring the only way for the the chromosome to get both mutations is if there is an odd number of crossovers between the two source chromosomes between the two mutant genes. Depending on how close together the genes are this might be very difficult. I've heard some information that sounds like this could possibly be happening in leopard geckos and it is documented with the long hair and banded mutations in Syrian hamsters. I've also suspected that green and labyrinth might be linked in Burmese pythons but it could also just be a case of epistasis where the green/patternless mutations just "stands over" or covers the labyrinth appearance.



One other possibility I can think of is that two genes might be a lethal combination. Maybe with the leopard geckos the combined effect of the two mutations results in an animal that it too sickly to live.



Many of the combinations so far have been stunning and I’m sure there will be many more but just keep in mind nothing is a sure thing. Most will likely come off without a hitch as expected but the above possibilities might make a few of them more interesting.

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