Reptile & Amphibian Forums

Breeding sibling to sibling or offspring to parent ? WHat I'm wondering is what would be least likely to produce defects. Maybe they would be equally the same for a risk ? Also to clear things up the scenario would be from 2 unrelated adults.

Keith

It ought to be equal. Both share 50% of their genes on average. If you're only inbreeding once there's still a pretty decent chance of getting healthy offspring.

I have been thinking about it all morning and I think actually offspring to adult would be better than sibs bred together. All sibs share genes from both parents . So basically siblings are more like each other than they are like one of the parents. Maybe Im wrong ?

Keith

Each sibling gets 50% of it's genes from each parent, making a total of 100%. So the parent and the sibling are about 50% related. That's the easy part.
(work brain work)
Now... Let's say sibling A got gene X from its mother. There's a 50% chance that sibling B also got gene X from it's mother, but there's also a 50% chance that sibling B got that gene from its father. So for any given genes (and therefore for all genes) the siblings will share on average 50% of them.

In short, you share half your genes with your mother and half with your father, but you also share half of them with your brother because he got his genes from the same place, only mixed up...

So, say one parent has a bad recessive gene that would get expressed in the F2 generation through inbreeding (this is the only reason inbreeding is bad). If we don't know which parent has it, a parent-sibling mating is just as likely to produce offspring homozygous for a bad gene as is a sibling-sibling breeding.

This is pretty verifiable.. I can dig it up in one of my books although they usually don't bother to spell it out like that.

I guess you have to consider what you are inbreeding for. if it is a wild type trait and the previous generation resulted from unrelated parents, the likelihood of inbred related flaws is probably very low. If it is something such as hypo melanism that has been excessively inbred and where the recessive gene mutation may potentially harbor other recessive alleles that are deleterious, homozygous expressions of these genes may give you a clutch full of dead embryos.
in other instances, inbreeding in isolated wild populations of animals(not necessarily snakes) is essential for RETAINING certain traits that are required to survive in a particular environment.go figure.
sexual reproduction is such a wonderful thing (keep your mind out of the gutter)since the result is never a rubber stamp of the parent; otherwise we could guarantee 1 out of EVERY 16 eggs would be a snow this or that, instead of the statistic being an average value from a large pool of offspring.
I say if possible ( if you have enough animals) to try both parent-offspring AND sibling-sibling pairings, and report back on what you get.
dB

If both parents are healthy specimens, no defects, unrelated, etc. then there should not be any problem. Pick the best looking, best feeders, and breed sibling to sibling as well as sibling back to parent, parental cross. If there is a hidden gene, that is bad, it may not show up in the F1 generation but may show up in the F2. If it does, put them down and stop. If not, you may lock in some real nice looking genetics with no ill effect. It was just a few short years ago that graybanded kings were the rage and many breeders proudly posted F1,F2,F3, and even F4 generation. I think the harm comes when something is wrong and the breeder continues the inbreeding, fails to put down the hatchlings, and sells the stock to get his money back. I also think the problem(s) are greater with boids, especially albino boas if you participate in the forum it's a debated topic. I have F2 cal kings, no problem as well as F2 Okeetees. I'm especially proud of the okeetees and their pure clean lineage. Another example of this practice is ball python breeding. Purchase a high end male, breed it to as many females as possible, raise the female babies and have dad breed them. Albinos, axanthics, etc. with the cost being time not $$$.
Just my opinion.