Inter-breeding?

[Serpent_Nirvana]

I think you mean to say "inbreeding," not "inter-breeding" I think the term "interbreeding" is generally used to refer to hybridization between two different species or subspecies (ie, "Python curtus and Python brongersmai can interbreed to produce ugly babies.")

Inbreeding is generally used to refer to the breeding of an animal to a first degree relative, such as sire to daughter, dam to son, brother to sister.

Line breeding is a more general term that refers to the breeding of related stock. This could be very closely related (first degree), or could be cousin to cousin, grandfather to granddaughter, etc., or even more distant -- second cousins, etc..

The good thing about line breeding is that it tends to "fix" the good traits in a line -- for example, in chinchillas, we might line breed to fix the trait of having a nice coat into a given bloodline. Surprisingly, breeding together two totally unrelated animals with similar phenotypic traits may or may not produce consistent, good-looking offspring, but breeding together two animals that are somewhat related generally will.

The downside of inbreeding is that it decreases genetic diversity. The way I see it, there are three major problems that may arise from this:

1. "Fixing" of bad traits -- The bad traits (lousy hips, cherry eye, etc. -- listing off some purebred dog problems now) are going to get "fixed" in the bloodline along with the good, and can be REALLY hard to breed out.

2. Manifestation of recessive genetic disorders -- Just like some of our favorite phenotypic traits like pied and albino are recessive and can be brought out by breeding two gene carriers (hets), so too can crappy recessive diseases such as (going back to chinchillas now!) malocclusion (tooth problems). I have heard it argued that this may be viewed as a good thing, though, as it lets you know that the problem is in the bloodline and you can cull or possibly breed to correct it, whereas had you only outcrossed, the problem would have stayed silent. I don't know if I buy that argument or not.

3. Loss of genetic diversity in the immune system -- This is a HUGE problem in wild populations of endangered animals such as cheetahs, and my guess is that it may be a bigger problem in captive collections of animals than we know about. The whole reason sex evolved (most likely) was for genetic diversity -- not so much in those things we can see, but in the animals' immune systems. One animal may have immunity to a disease that another animal does not. So when you lose genetic diversity, if a disease comes along that no animal in the population has any immune tolerance to ... That population is screwed.

I hypothesize that this may explain some seemingly "random" die-offs in various collections and colonies of captive animals ... But that's just a theory.

In my opinion (again, my OPINION, there are LOTS of opinions on inbreeding and line breeding out there!) line breeding in small amounts is justifiable as long as the animals involved are healthy -- mainly if you're trying to really "fix" a trait in a certain bloodline, particularly in mammal breeds where there is really no other way to produce a consistent breed of animal. For the most part, I don't see a *huge* reason to do it with snakes -- I'd rather just trade my offspring for similar offspring to maintain a higher degree of genetic diversity.

Would you get monstrous, defective babies breeding him back to one of his daughters first-generation? No, probably not, but with a morph as common as the pastel, I don't really see a reason to risk it. That male is very nice and I agree, he has great blushing -- but I'll bet you can find a very nice, unrelated female that has a similar phenotype, and I would be somewhat surprised if that didn't produce nice offspring.