Mitchell Mulks

Doug, I'll do my best to explain how this is possible genetically.

So, it's well documented that the human and chimp genomes are greater than 98% identical because of shared common ancestry. That means, all the dna that comprises the 23 different chromosomes in humans is 98% or greater identical. Therefore, less than 2% of differing dna between humans and chimps is what makes our two species different from one another. Similarly, it's been shown that corns and kings arise from common ancestry, so I'd imagine the difference in their genome is only due to a few percent too.

When a striped cal king x corn cross is performed, yes, the offsprings genomes are comprised of 50% cal king and 50% corn. However, and this is a big deal, very few of the genes handed down from each parental species differs from one another. Most of the time, an F1 hybrid, when chromosomes align, the genes residing at a particular loci on sister chromosomes will be identical; therefore it makes no difference which species passed down that portion of the hatchling's genome. Occasionally though genes at the same loci will differ because they evolved in different directions when cal kings and corns diverged from their most common ancestor. It's those conditions, when the genes are heterozygous with respect to which species donated the genes, that makes hybrids look unlike either of the parental species.

So, if less than 2% of the genome between a corn and king (since they are highly related I'd imagine it's around this number) differs, then even a much smaller fraction of those differences are probably responsible for the phenotype of the animal that we see when we look at them. Some of the genomic differences between species will affect organ function, some maybe on how metabolism functions, but for certain not all the genomic differences between the two species will affect the pattern and physique of the snake.

When you create a jungle corn by breeding a cal king to a corn, the only traits we can artificially select are the ones we can see. The gene responsible for the tessera pattern is one of those genes. It's dominant in that with only one copy of the gene at a single loci, regardless of which copy of the gene (cal king or corn ) sits at the other loci on the sister chromosome, the pattern will forma a thing dorsal stripe and tessellated lateral flanks. After the first hybrid event, from the F1's, the person orchestrating the artificial selection experiments will choose to hold back only those offspring with the tessera pattern, and a body type and pattern that most closely resembles a corn snake. From this choice the breeder is propagating the dominant gene that makes the tessera pattern and any other genes that more closely resemble a corn snake. When that F1 is bred to a pure corn to make the F2 generation we say that ~75% of the genome of the hatchlings will be corn snake and ~25% cal king (however, it's possible for the F1 snake to donate all corn snake genes to the F2 offspring, making the F2's 100% corn...but odds dictate that is HIGHLY unlikely to occur. But what does occur is the F2 offspring are now ~75% corn snake. Of that 75% corn snake genome, only a fraction is actually responsible for creating the phenotype that the breeder selects. Every time the breeder does subsequent pairings he or she is ALWAYS perpetuating the tessera gene, and a greater and greater majority of genes that create the morphological characters we associate with corn snakes. The cal king genes are eliminated from these subsequent lines, therefore greatly reducing any king snake 'noise' you'll see in pattern development. By four or five generations the majority of the genes responsible for actually creating the corn snake phenotype have been selected and perpetuated by the breeder, all the while the king snake genes have been eliminated from the strains. Because the behavior of the tessera gene is dominant when in a heterozygous state, when one of the hatchlings doesn't receive the tessera gene, the majority of the pattern genes are now corn snake...so the F4 and F5's will look almost identical to pure corns.

It's very straight forward how this occurs genetically, and it's very possible to artificially select against the majority of cal king pattern genes that have the largest affect on pattern development. Within a few generations the vast majority of genes actively dictating pattern and physique development will be corn snake in origin, with only the tessera pattern gene always being selected for because it's easy to identify. It's actually quite possible that over four generations you could still have a nearly 50-50 ratio of corn to cal king genes, with the main difference between that being that the breeder has artificially removed the minute number of genes responsible for creating the cal king pattern from the equation! Therefore, you could have created a snake that is identical to the tessera corns we love, but is a 50-50 hybrid genetically!!!! That's the really cool thing about genetics. It also demonstrates the sheer power associated with artificial selection. Humans have been artificially selecting pattern elements of foods and animals for thousands of years. Do you think they were thinking about genes when they held back seeds from corn that produced larger kernels and bigger reproductive fruits? No, they were simply thinking "larger is better". They were unconsciously doing away with the genes for small growth, and favoring the genes for larger fruit! The same thing, in my opinion, has been done with tesseras.

Doug, I hope you see that I've answered your question above. How cool would that be to honestly hold a tessera that is almost exactly 50% cal king and 50% corn snake and not have known it a minute prior?! Like I said, regardless of whether or not they're hybrids or not, I love the morph and I'll continue to work with them. All I'm doing here is presenting to everyone a VERY REALISTIC hypotheses for their "out-of-nowhere" arrival.

Btw, I realize that Don was the one that commercially introduced the morph into the market, and by no means do I at all think he did so thinking they were anything but pure corn. Heck, he got his stock from KJ, whom he got from someone else who got them from the breeder who had them advertised in the classified pages. Can you all see where there can be an issue with really knowing the origin of this morph? Don is one of the most stand-up corn breeders I've had the pleasure of speaking with, and in none of my posts have I, nor would I, ever insinuate that his introduction of these into the corn market wasn't 100% with the best intentions. I just think the original seller of these had some F4 or F5 cal king x corn crosses they tired of and sold off as pure. Like I said, I've heard too many comments from small breeders where they've shared stories of their snakes breeding profits that involved intentionally lying about the genetics (whether locality data or hybrid origins) to the buyer.

I hope that helps Doug!