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The Cultivars (morphs)/Genetics Issues Discussions about genetics issues and/or the various cultivars for cornsnakes commercially available.

king snake influence in tessera morph?
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Old 01-14-2013, 07:58 PM   #91
Carpe Serpentis
I like the idea of breeding them together. If they are located on different alleles it may be possible to get a third phenotype proving that they are indeed different expressions of a similar looking trait.
 
Old 01-14-2013, 08:06 PM   #92
DMong
Quote:
Originally Posted by Carpe Serpentis View Post
Entire clutches are not needed to show that some trait can be line bred into an animal and produce progeny that are within a certain guideline. One need only look at the many breeds of dogs that have all been selectively bred to exhibit certain traits to such an extent that these traits are given names such as poodle, zu, pomeranian, klee kai, etc. Man has been breeding hybridizing for a few years now and to think that snakes are one of those animals that for one reason or another has a strong taboo with some when it regards hybridizing is strange to me personally when so many other animals are hybridized without so much as anyone even blinking an eye in comparison. A good breeder can in fact breed any trait into his line and have it breed true after a few generations. Breeding out the unwanted genes can also be done with a rudimentary understanding of genetics and an eye for detail.
Ahhh yes, you and the ol' mutt dog thing again!..LOL!

I can always count on you for a hybrid 101 lesson. And YES!, entire clutches definitely WOULD be needed in the case ot THOSE snakes Mitch posted to bolster any of this at all, not just locating singled-out examples here and there of some individual Cal. king x corn crosses that looks similar to Tesseras.

Explain then precisely HOW everyone always consistently gets either absolutely NORMAL phenotype corns OR 50% totally whacky Tessera phenotypes every time a Tessera x normal corn is bred??? If this alleged "hybrid" Cal. king gene is so over-powering, then how would 50% textbook phenotypic NORMAL CORNS be produced within every single clutch of these? I assure you and everyone else, if these were hybrids, every single offspring would NOT be either a Tessera phenotype or COMPLETELY NORMAL corn phenotype EVERY SINGLE TIME FOR GENERATION AFTER GENERATION.

I do not see how it is possible that all these snakes would be retaining only the striping pattern of a Cal. king, yet have the entire textbook morphology of 100% cornsnake in the many countless numbers of clutches produced around the world. And IF the hybrid Cal. king striping is so incredibly dominating (as is being portrayed), then how are ANY NORMAL phenotypic corns produced at all, much less 50% textbook corn phenotypes CONSISTENTLY as the sun rising from the east and setting from the west???


~Doug
 
Old 01-14-2013, 08:16 PM   #93
MotleyMedusa7
I'm not sure one way or the other on this,but I did have a question-which Don touched on- if one group of rat snakes(Leopard rat snakes)can develop this striped/tesselated pattern -why is it so implausible that another group can? I read their bellies can also range from white to checkered to black which sounds like a Tessera corn.... not being sarcastic or anything-this is a genuine question--

http://acsnakes.co.uk/acs/leopard.htm



 
Old 01-14-2013, 08:20 PM   #94
DMong
Quote:
Originally Posted by Chip View Post
Those tri-colored hogs look almost exactly like milksnakes.
I heard that Cristopher Columbus and his hybridizing partner created those from their Western Hog x Pueblan milk project...LOL!!

They were bored to death as they sailed on the Nina, Pinta and Santa Maria and needed something useless to do. You know, similar to what they still do today.........do it just because they can.
 
Old 01-14-2013, 08:25 PM   #95
Rich Z
Can anyone remember he LAST new genetic form of the corn snake that was NOT thought to be a hybrid by someone?

So the bulk of Joe Pierce's argument of tesseras being hybrids is based on variable and/or patternless belly pattern? Heck, I can't remember any cultivar of the corn snakes I used to work with that DIDN'T at one time or another, produce some specimens with variable or non patterned bellies. So Motley's are now hybrids? Blood Reds are hybrids? Stripes are hybrids? I produced MANY Miami phase and Silver Queens with completely or partially patternless bellies. Heck, look at the bellies on Upper Keys corns. That is the stock that the Ashy (Cinder) corns originally came from. And of course, the Ultras also had weakly patterned abdomens.

So if it doesn't fit in Box A or Box B, neatly, it MUST be a hybrid? Maybe we just need more boxes defined.

I would imagine it's getting to be close to the point where most people will be scared to death to announce that they have produced something new in corn snakes because of the gauntlet they will have to run to attempt to prove the ancestry or have their reputation suffer.

And I am still waiting for someone to explain to me how it is that new genetic traits in the corn snakes can ONLY be produced via hybridization with another species or genus. That IS what some people seem to be claiming, you know....

Lord have MERCY, I am glad I retired from this.
 
Old 01-14-2013, 08:57 PM   #96
Kevin S.
Quote:
Originally Posted by DMong View Post
I do not see how it is possible that all these snakes would be retaining only the striping pattern of a Cal. king, yet have the entire textbook morphology of 100% cornsnake in the many countless numbers of clutches produced around the world.
Let's say someone breeds an albino cal king to a normal corn. Breed those het jungles together and you get some albino jungles. Breed one of the albino jungles to a normal corn and you get super corns het albino...continue on with this pattern for a few generations and eventually you'll get albino snakes that have the scalation and other morphological characteristics of a corn, but they're not amel corns-they got their albinism from a cal king ancestor. It'd be much simpler with a dominant trait (like tessera) since you'd have no hets to deal with and could just breed a funky patterned offspring to a pure corn and get more of the same pattern with progressively more corn influence each time.

IF the dominant pattern mutation came from a cal king or resulted from the combination of corn and king genes, that's how it would be done. So the question isn't how could you breed away the king traits and keep the pattern, but whether or not a king would be necessary to originate the pattern in the first place. We'll never know at this point and as I said before, I don't see it being a very critical question regardless...makes for some interesting conversation though.
 
Old 01-14-2013, 09:08 PM   #97
Kevin S.
Quote:
Originally Posted by Nanci View Post
I don't think that snake looks anything like a Tessera. But- we have already discussed that particular snake in a different thread.
Nanci, wouldn't you agree that this looks like a pure tessera...


...and this looks like a normal corn?
 
Old 01-14-2013, 09:13 PM   #98
Mitchell Mulks
Quote:
I do not see how it is possible that all these snakes would be retaining only the striping pattern of a Cal. king, yet have the entire textbook morphology of 100% cornsnake in the many countless numbers of clutches produced around the world. And IF the hybrid Cal. king striping is so incredibly dominating (as is being portrayed), then how are ANY NORMAL phenotypic corns produced at all, much less 50% textbook corn phenotypes CONSISTENTLY as the sun rising from the east and setting from the west???
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!
 
Old 01-14-2013, 09:21 PM   #99
Mitchell Mulks
Quote:
So Motley's are now hybrids? Blood Reds are hybrids? Stripes are hybrids? I produced MANY Miami phase and Silver Queens with completely or partially patternless bellies. Heck, look at the bellies on Upper Keys corns. That is the stock that the Ashy (Cinder) corns originally came from. And of course, the Ultras also had weakly patterned abdomens.
No, motleys are not hybrids. I think you're misunderstanding the variation Joe is talking about (variation I also agree about too). Within a single clutch of motleys you get all clear bellies (maybe a little black speckling, but no checkers...with the exception of sunkissed...but those checkers are few and far between). Within a single clutch of bloods you get a clear belly with some lateral color bleeding into the ventral scales (you even have the translucent scales in the center of each ventral scale; which is a 100% way of identifying blood stripes from a stripe het blood x stripe het blood pairing). What you don't get in those examples is what occurs in tesseras. Within a SINGLE CLUTCH you'll have siblings with clear bellies, some with checkers, some completely checkered, and some with the upper half absent of pigment only to have the lower half go to full checkers. That doesn't occur with any other corn morph! It's a marker that's indicative of two genes, both from independent evolutionary origin, that reside at the same loci on sister chromosomes. It's what happens when two genes are having compatibility issues during development; one of the genes is giving instructions for one pattern while the other is giving another. You simply don't see this WITHIN CLUTCHES with any other morph.
 
Old 01-14-2013, 09:22 PM   #100
Nanci
Kevin, I would say the one snake does look like a Tessera, and the other snake does not look like a [pure] normal corn.
 

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