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Out crossing

MesoCorney

New member
I have seen this term used in several different contexts and am confused on the meaning. I have read that it is introducing genes of another species then continued breeding to the original species to dilute the "borrowed" genes. I have also seen out crossed with snakes from seemingly pure stock. I am wondering if I am confused about the meaning or if I am just confused about the snakes. I see it quite often so would be pretty surprised if all the snakes labeled this are in fact hybrids.
 
From what I understand, it does not mean introducing a new species. Some of the morphs are line bred to get a certain look, but eventually they might start having genetic problems from being bred from a limited gene pool, so an unrelated snake can be brought in to breed, and then they try to breed it back to the look they want.

Some purebred dogs, like Cavalier King Charles spaniels often have severe heart issues because today's CKCSs came from a very small original group of dogs that were not outcrossed (or else they wouldn't be considered 'purebred').

I might be completely wrong, that's just what I've always believed it meant.
 
No that makes sense. In that case you could use the term with both a pure and a hybrid snake. It also explains why I see it so often as many breeders seemed obsessed with line breeding. Breeding an animal to a related animal in a line over time can lead to some pretty nasty health problems. It would not surprise me at all if the stargazer gene was due to line breeding.
 
By definition, if used to identify a hybrid, it is a misuses of the word.
out·cross (out′krôs′, -krŏs′)
v. out·crossed, out·cross·ing, out·cross·es
v.tr.
1. To mate (an animal) to an unrelated individual of the same species or breed.
 
Stargazing is not due to line breeding. It is a simple recessive mutation, just as amel, anery, hypo, motley, etc are simple recessive mutations.

I have a couple line breeding projects waiting in the wings. I will be outcrossing every few generations to keep the line healthy.
 
The problems that come from line breeding are more like enlarged hearts or in the case of chihuahua a larger then normal soft spot on the top of the head. They are almost never simple recessive traits. In a canary breeding project I was part of about 10 years ago. we were trying to improve the spangles and the cap. In the case of the cap as we were selecting for a clearer cap which only showed the ground color. as we held back and start selecting for a clearer cap we started get bold spots that prove to be hard to eliminate. So we had to outcross to fix the problem and not lose all the benefits. it add a couple extra seasons but turned out really nice.
 
Another definition:
out-cross
[v. out-kraws, -kros; n. out-kraws, -kros]
verb (used with object)
1. to cross (animals or plants) by breeding individuals of different strains but, usually, of the same breed.
2.to produce (a hybrid) by this method.
noun
3.a hybrid animal or plant so produced.
4. an act of outcrossing.

I am pretty sure any recessive trait will be propagated by line breeding. The chance of two alleles being the same in two related animals is much higher. In fact all of those morphs were more then likely line bred to get a certain look. This is the reason you don't find many of these traits in the wild. In nature populations are constantly outcrossed and unless a recessive gene is useful and lucky it will be more than likely lost.
 
Another definition:
out-cross
[v. out-kraws, -kros; n. out-kraws, -kros]
verb (used with object)
1. to cross (animals or plants) by breeding individuals of different strains but, usually, of the same breed.
2.to produce (a hybrid) by this method.
noun
3.a hybrid animal or plant so produced.
4. an act of outcrossing.

I am pretty sure any recessive trait will be propagated by line breeding. The chance of two alleles being the same in two related animals is much higher. In fact all of those morphs were more then likely line bred to get a certain look. This is the reason you don't find many of these traits in the wild. In nature populations are constantly outcrossed and unless a recessive gene is useful and lucky it will be more than likely lost.

In a genetics sense, the term is properly defined as Jereme stated. Hybridization can come into play, but again the term is more valued towards introducing genes within the same species. The idea and concept is that by outcrossing to an unrelated individual that you are increasing genetic diversity all the while assumingly reducing disease and/or "negative" genetic anomalies. The practice is used in line breeding in attempting to restore breeding vigor. It should be noted that line breeding is different from inbreeding. Line breeding results in a line sharing a common ancestor. Inbreeding is, essentially, a more dramatic form of line breeding where the common ancestor are parents and the offspring are more closely related.

A misconception is that inbreeding only brings about recessive traits and that recessive traits are "negative" or undesired traits. Dominant traits can also be perpetuated through inbreeding and can also be of negative or undesirable results, e.g., achondroplasia in humans, an autosomal dominant dwarfism mutation. In this case, being homozygous recessive results in "normal" height and limb-length, and even 1 copy of the mutation, i.e., being "het" is enough to suffer from the disorder.

In contrast to your last statement, many corn mutation are actually wild-derived. The first albino corn was road cruised circa 1953. There are natural populations of anerythristics (all 3 types) in FL, with anery Type A originating from around Fort Meyers if I recall correctly. The first caramel corn, again if I recall correctly, was a wild caught animal in a FL pet store that Rich Zulchowski stopped in and purchased. The palmetto corn was a wild caught. Same goes for a number of other "non-natural" mutations of other species (albino harquahala rosy boas, albino whitewater rosy boa, albino California kingsnakes, etc.) that were wild occurring.

Food for thought... Outcrossing can also result in outbreeding depression, where the outcrossed offspring actually result in less vigor/fitness than those offspring from line breeding or even inbreeding. So just because you outcross doesn't always mean you're strengthening lines.

You'd be surprised how related wild populations can be, particularly if they have a small range to begin with or of an isolated population. I believe there was an eastern box turtle study recently documenting this.

Additional food for thought, this very subject is why I rarely breed homozygous recessive to homozygous recessive (same for homo. dominant). I typically breed a heterozygote to a homozygote (example, my current male breeder tessera is het for butter/amber stripe and one of the females he gets paired to is a full homozygous recessive butter stripe). I may produce lots of hets, but heterozygosity can also help in keeping a line strong.
 
Wow! I love your posts, HerpsofNM! I always learn so much. Thank you! So if I get this right.....If I breed my Amel that I got here in CA to my Tequila Sunrise, that would be outcrossing, correct? But if I had two Tequila Sunrises that would be line breeding unless they were parents or siblings and then this would be inbreeding?
 
I am entirely aware many of these morphs were wild caught but compared to normal they are far out numbered and most an outright anomaly. I do not know this for sure but statically speaking in the case of a recessive gene two wild caught snakes were often line bred to create the pet populations we see today. Traits like anerythristic it is easy to see how this would be useful in hiding in nature, but many of these morphs this is not the case. I would be hard pressed to believe that most were not from line breeding. According to Darwin in general mutations negatively affect a species, but it is that one in a million that will be useful and propagate in the wild. This is why evolution is such a slow process. I think you missed my point about line breeding and the propagation of recessive genes. All I was trying to say is that line breeding can in fact propagate recessive genes, and did not comment on dominant ones. For a recessive trait it is more likely to be homozygous from two related animals than two unrelated animals because they are more likely to hold the same gene. Where as a dominant gene can show if only one of the parents holds the gene. Dominant traits are often caught much more quickly and in a negative form cut out of a line. All I was trying to say is that line breeding can in fact propagate recessive genes. Species living in close quarters leads most to see that a population is in fact related, but I think you would be more surprised at some of the ways nature actually encourages outcrossing. No doubt there are exceptions to every rule, but when discussing genes it is best to only include generalizations.
 
Most people assume breedable traits are rare, so they “have to” inbreed to get homozygous offspring. That assumption is not always true.

Some traits pop up now and then like intensive red or yellow pigmentation, dark blotch color, wide blotch borders or some pattern variations (banded/Aztec). These are polygenetic traits that are very much breedable traits.
With traits that just pop up from time to time, you can select two snakes that is not related to each other without inbreeding- or linebreeding. Just find snakes with the traits you like and breed them together!

With polygenetic traits, if both parents were selected for the same trait, some offspring will look like their parents, some will be more ordinary than their parents, but some will look more extreme than their parents too.

You just need to find 2 unrelated snakes with the preferred traits to get the first generation offspring without inbreeding, F1.
If you find a third snake with the trait to breed to your best F1 offspring with your trait then you get a second generation offspring, F2, that is selectively bred without inbreeding.

If you see a trait that just 1 of 100 cornsnakes have, then go and look at 300 snakes to find the 3 snakes you need to selectively breed two generations of offspring without inbreeding.

Selective breeding for polygenetic traits is more about selection brood stock than linebreeding or inbreeding.
 
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