Caudate Genetics

[aaron]

I know that with many animals, breeding brother-sister or daughter-father can and usually does result in weaker offspring and/or birth defects.

Many caudates live in or return to the same breeding ponds for their entire lives, as well as their offspring. After a long period of time, one would think that all of the animals in the ponds would be at least distantly related. I remember hearing of a private keeper that had inbred his animals for several generations and noticed no problems. Have there been any studies on the effects of inbreeding on caudates?

~Aaron

 

[jesper]

Ah, exactly what I was wondering too

 

[coen]

I think breeding ponds offer a much larger terrain than a tank in your house could, thus providing more space for a much larger group of newts, which results in a large gap between the relationships of the newts in it.

 

[paris]

in breeding ponds too, they are in the outdoors with all that entails..so usually only the fittest will live long enough to get the chance to breed.

 

[jesper]

Well, the question I wanted to be answered was not about ponds but if captive inbreeding has shown to be problematic.

 

[coen]

I know Jesper

Unfortunatly I have little to no knowledge about this, so I just gave my opinion on the subject Aaron presented concerning the ponds. I think however that inbreeding in a very little community of newts could give some genetic problems.

 

[edward]

In general inbreeding does not show the effects as rapidily as you may see in mammals,birds and some fish species. For example (if I remember correctly) Pueblan milksnakes (L. triagulum campbelli) originated from 7 adults into the thousands of animals available in the pet trade today. While it is always a good idea to maximize genetic diversity, so far it appears that there is little problem in general with herps surrounding inbreeding.
Ed

 

[jesper]

Thanks for the info Ed!

 

[jennifer]

I think that, like everything in biology, it's unpredictable. I certainly know of cases where breeding between closely related newts/sals resulted in perfectly healthy offspring. But I have also had one experience that leads me to believe that, in some cases, inbreeding can cause problems.

I raised a very healthy batch of T. karelinii from eggs I received (produced by WC animals). I experienced zero mortality during the larval/juvenile period. From a few of these CB animals, I raised eggs, but had terrible problems with fungal infections in the larvae (over 50% mortality among the larvae during the first weeks after hatching). Some of those eggs were raised by other people, who also had mortality problems with the early larvae.

This year I'm raising the same species from a group of mostly WC adults, and again have had no problems with early mortality among the larvae. (I did have a disease outbreak among the mid-stage larvae, but that was treatable with antibiotics, and only affected some tubs, not all.)

Based on this experience, I am trying to stick with breeding unrelated adults as much as possible. I believe that it is worthwhile, whenever possible, to trade adults with other keepers in order to have unrelated (or less related) animals. If I'm going to invest my time in raising young, I don't want to waste my time on young that may be handicapped by inbreeding.

In species that are already highly inbred (axolotls, for example), this is much less of an issue. After several generations of inbreeding, genetic defects tend to be weeded out.

 

[aaron]

Thanks for the info Ed and Jen. My main reason for presenting this is that I was thinking about Sara's axolotl Chance. I was wondering if breeding the offspring to each other could produce animals resembling chance.
~Aaron

 

[edward]

Hi Jen,
While inbreeding depression can cause the symptoms seen in your newts I would look at other causes in animals that close to original wc parents. What seems to happen in this sort of situation in some herps is that there is some nutritional deficency that does not show up until egg formaulation occurs. The Zoo used to have pretty heavy loss in Corucia zebrata neonates until the amount of vitamin A was increased in the lizards diet... In inbreeding one of more common seen depressions are problems with sperm motility but I would be surprised to see it that quickly in your newts Jen (although outcrossing is always a good idea).
In trying to fix a trait, it is usually ideal to pick several different breeding groups that express the desired characteristic and breed within each line for that trait. If one line starts to become nonviable then outcross to one of the other lines as unless the chosen trait is linked to problems this outcrossing can help deal with inbreeding depression. (This is how breeders develope new lines of fish, chickens, ect).
As a side note cheetahs are an excellant example of an animal that is closely inbreed. All cheetahs are so closely related that you can graft skin between any two randomnly chosen cheetahs without any sign of rejection.
Sorry for the ramnbling but I'm not quite awake.
Ed