Reptile & Amphibian Forums

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Happy herping

in breeding, breeding closely related animals, can have side effects. they can be good ones or bad ones. in either case, the side effects can occur because BOTH animals -- being closely related -- may have the same hidden gene (for a good or bad consequence).

good example: you breed a pair consisting of an albino x a normal. All the babies are carrying the hidden (recessive) gene for albinism (and it's really amelanism, but that's a story for another time). So you breed brother x sister of the babies, and 1/4 of the babies will get that amelanistic gene from EACH parent, and when they have TWO of that recessive gene, they show the effect, in this case amelanism. Presumably, a desirable side effect.

In this example, above, one of the initial parents is already showing the effect (the "albino". But the example couild instead consist of ONE parent that is carrying the hidden gene. In that example, HALF the babies will also have the hidden gene for amelanism. If the brother sister pair you select (and there's no way to tell by looking) both have that hidden gene, then again, 1/4th of the babies will be "albinos". So you've again gotten a presumably desirable side effect from two original parents NEITHER of which showed that side effect.

The same thing can happen with a gene defect, creating a bad example: one of the original parents is carrying a hidden gene for any defect, doesn't matter, take your choice. but if it's a recessive mutation, one resulting from that single gene, then half the babies will carry that hidden gene, and if the brother-sister pair you select (remember, there's no way to tell by looking whether or not they've got the hidden genel) both have the hidden gene, one-fourth of the babies will show the defect. An example in humans would be cystic fibrosis, a disease that is hereditary, recessive, and potentially fatal.

I used to breed birds. People will often "in breed" birds from a line that is exceptionally large, for example, because the babies from that line will have a higher chance of producing larger-than-normal babies than babies selected randomly from the entire bird population. But conversely, yes, there is always the chance that the "in breeding" could also produce birds showing any gene defect that was hidden in either or both of the original parents.

I hope this makes sense. There's nothing inherently right or wrong about inbreeding, it simply increases the chances for hidden characteristics to appear, and yes, some of them can be undesirable.

peace
terry dunham
albino tricolors