Reptile & Amphibian Forums

It seems that this has been discussed/debated before over the years, but I can't find a common answer. Do you need to pair 2 leucistics together to get a clutch of all leucistics, or can you pair 1 leucistic and 1 normal (not het) and get a mix? My guess is they will all look normal in the second scenario.

You'll never get ALL leucistics by pairing a leucy with a normal. Depending on the bloodline of leucistic, there is a chance of producing some leucistics and some rusties out of a leucy x normal pairing, but the chances of getting leucies are slim.

Others may tell you it's no possible to get leucistic babies from a leucy x normal pairing, but I've seen it happen.

Only if the normal is a carrier of the gene for leucistic, a het.

I am not too sure of where this gene is carried but if it is a simple recessive trait then you should get about half the babies to be leucistic and half to be heterozygous for leucistic, BUT ONLY if the normal looking parent is heterozygous for leucistic.

If the normal parent is not a carrier of the gene you will not get any leucistic offspring, but all should be carriers of the gene. You would then have to breed one of the offspring back to the leucistic parent to get leucistic offspring.

L L
l Ll Ll
l Ll Ll

Below is how it would work if these genetics are straight forward. LL is homozygous Leucistic and Ll is a heterozygous snake carrying the gene for Leucisism.

L L
L LL LL
l Ll Ll

Again, I am not a genetic expert on Leucistic Texas ratsnakes, but if it is not linked to other genes to be turned on this is the basics. Someone else may have much more information on this.

Good luck!
Chris

Sorry... the genetics charts look like [bleep] after they get posted. Check out these websites though:

http://www.supersnakes.com/gwiz.htm

http://anthro.palomar.edu/mendel/mendel_2.htm

Note: When talking about leucistic before, I was talking about it specifically in BLACK rat snakes. I don't think the strain that was introduced through Texas rats works the same way, because there is no rusty gene in Texas rats, as far as I know.

Leucistic appears to work as a simple recessive trait MOST of the time, but not always. Somehow or another, it's linked with the rusty gene.

Maybe the leucistic gene in Texas rats can be predicted as simple recessive, but in black rats, it can't.

I've heard of people doing several different breeding experiments with leucistic and rusty black rats, and never coming up with anything conclusive. I've heard of rusties being bred together, and never producing a leucistic baby, and then after 10 years of breeding, one leucistic pops up. I've heard of people breeding two leucistics, and getting rusty babies (which shouldn't be possible!). I've heard of people breeding a rusty to a leucistic, and getting rusty/normal babies, then breeding that same rusty to another leucistic, and getting leucistic babies.

It's kind of a crapshoot, even if most of the time it works like a simple recessive trait.

Ronnie Nocera

>>Only if the normal is a carrier of the gene for leucistic, a het.
>>
>>I am not too sure of where this gene is carried but if it is a simple recessive trait then you should get about half the babies to be leucistic and half to be heterozygous for leucistic, BUT ONLY if the normal looking parent is heterozygous for leucistic.
>>
>>If the normal parent is not a carrier of the gene you will not get any leucistic offspring, but all should be carriers of the gene. You would then have to breed one of the offspring back to the leucistic parent to get leucistic offspring.
>>
>> L L
>>l Ll Ll
>>l Ll Ll
>>
>>Below is how it would work if these genetics are straight forward. LL is homozygous Leucistic and Ll is a heterozygous snake carrying the gene for Leucisism.
>>
>> L L
>>L LL LL
>>l Ll Ll
>>
>>Again, I am not a genetic expert on Leucistic Texas ratsnakes, but if it is not linked to other genes to be turned on this is the basics. Someone else may have much more information on this.
>>
>>Good luck!
>>Chris

I bred leucistic black rats many years ago, before they were so popular, and always had a fairly predictable outcome on all offspring. I believe that the rusty is a co-dom mutation, as it always produced (for me) rusties and normals in first gen offspring of rusty to normal pairings. Rusty to rusty would produce rusties, leucistics, and, very rarely, a normal. I believe leucistics to be the super form of the rusty co dom, much as it works in many of the Ball python co doms (see Fire, mojave, etc) This is further supported by leu to leu pairings always yielding only leu offspring and leu to rusty only producing leus and rusties, never any normals.
These are just my observations with 30 or so clutches, if anyone has contradictory findings, I would love to hear your input.

Derek
Cape Fear Reptiles

It seems that's how it works MOST of the time, but not always. I've heard of a bunch of people breeding rusty x rusty, and only ever getting rusty offspring, never a leucistic, so rusty isn't always het. leucistic.

Ronnie

I see your logic, but I still maintain that the leucistic is the super form of the rusty co dominant. As for those that have produced no leucistics from a season or two (or more) of rusty to rusty pairings, think of the odds of producing a leu from this. The chance of getting a leu is 25% in each egg. Add to this the bewildering fact that the gene that you want to produce will always be in the egg that goes bad in the incubator. We have all had this experience at one time or another with simple recessive or co dom. Below are my experiences with different pairings over ten years with no variation:

normal to rusty yields rusty and normals
rusty to rusty yields normal, rusty, and leucistic
rusty to leu yields rusty and leucistic
leu to leu yields only leu
leu to normal yields all rusty

Again, this never varied in the years that I produced this line. Of course, the ratios did vary, but that's what happens. I think you will find that this is what expected from a co dominant mutation.

Again, I welcome any input on breeding experience.

Derek
Cape Fear Reptiles