# Inbreeding



## gary1218 (Dec 31, 2005)

I'm new to the dart frog hobby and my background is with tropical fish, mainly discus & rams. With the tropical fish it isn't uncommon to breed fish from the same spawn. Certainly not generation after generation.

How is it with the dart frogs? Are you very careful that your pairs are from different parents?

Thanks,
GARY


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## Ben_C (Jun 25, 2004)

Hi Gary,
Getting unrelated pairs is always better than breeding clutchmates.
If this thread is like any of the previous ones similar, someone will without fail post claiming that "...ill effects are not noticed through inbreeding up to 9 generations..." (occasionally people cite 7 generations). However, I would be very skeptical of this claim and would discourage inbreeding of any kind.
If somebody can post an actual study from the primary literature looking at any dendrobatid with inbreeding not playing any factor in general well being for 9 generations I would be very surprised...
I hope this helps,
Ben


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## littlefrog (Sep 13, 2005)

It would depend on the genetics of the species. Some animals have gone through relatively recent evolutionary 'bottlenecks', for example cheetahs are thought to have been reduced to almost extinction at some point in relatively recent (pre-human, I think) history, and have only a very limited pool of alleles to choose from. Inbred mouse strains are a human invention, but are also almost completely homozygous at all gene loci. They seem to be healthy enough (although they wouldn't survive well in the wild).

I don't know that the necessary studies have been done in dart frogs (and certainly not on all species) to say just how much allelic variation is available to choose from. We could get a good idea if we could generate a SNP (single nucleotide polymorphism) map (and a genome map) of a representative species, but nobody is funding that. Somebody wants to fund it, I'll do it, but it is expensive to say the least. A 'classical' genetics approach would work too, but would take lots and lots of animals and a very devoted researcher. Maybe somebody is doing this.

I've been to a few seminars which suggest that much of the current south american rain forest habitat is quite recent (since the last ice age). I have no expertise in paleoclimatology, so this could be bogus, I guess. However, this might lead to a (testable, by somebody) hypothesis that many of the dart frog species are quite recent in origin, and presumably derived from small founder populations, and thus, perhaps (perhaps!!!) are quite homogenous in genotype. If they are homogenous, inbreeding would be less harmful. 

I can't think of any scenario where inbreeding is desirable, at least for long term preservation of the species (you could use it to generate and 'fix' interesting color morphs). But, it might not be unreasonable to expect that you could go 7 or 9 generations without seeing harmful effects. I don't think it is a great idea, but it might be necessary for very rare species. Remember too that we are changing these beasts just by keeping them in captivity. We lose animals that are genetically mal-adapted to living and breeding in vivariums.


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## defaced (May 23, 2005)

This is a topic that I've been pondering for a while. Thanks for the excellent reply littlefrog.



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## gary1218 (Dec 31, 2005)

Thanks guys.

I'm just "pondering" my first pdf purchase. I thought of going to one of the larger breeder/suppliers thinking that they would have mixed lines to pick from if I purchased 3-4 frogs. As opposed to buying from a local hobbyists that may have just one pair breeeding. 

Although, I do like to support local people. Maybe I can find a few different local breeders that have what I'm looking forward  

GARY


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## KeroKero (Jun 13, 2004)

If you want to get a breeding group all in one go with as mixed a group as you can get, I'd go with one of the larger breeders that do have the multiple bloodlines. I'm much more of a "frog here, frog there" type of person, and especially with froglets, you've got so much time to collect other members of their morph. Its just more expensive if you've gotta get them shipped from here and beyond.


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## Ed (Sep 19, 2004)

castenoticus are from a very small group of founders. As all of the frogs in the hobby are siblings from a couple of clutches that were from siblings produced from the original imports these are all inbred. There were no further releases from the original parents into the pet trade so there was no further F1 genes added to the lines. 

So how many generations of castenoticus do we think are in the hobby? I would be willing to suspect that it is greater than 7 generations and as they are all in effect incrossed siblings, I do not think that we have seen any deleterious effects as of yet. 

Ed


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## Michael Shrom (May 20, 2004)

I think line breeding is preferable to outcrossing. The problem with outcrossing is you aren't always certain if the morph or type you are breeding with is actually the type of your founding stock. The inbreeding article I remember was in the International Society for the Study of Dendrobatid frogs journal. I think it was a zoo in New York. I'll look it up. People often confuse problems associated with poor husbandry with problems from inbreeding.


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## bluedart (Sep 5, 2005)

The thing that is most worried about with inbreeding is that undesirable traits are often passed down again and again, and become dominant. Like the Kings and Queens in Europe had a disorder in which their blood didn't clot properly, and small cuts could kill them. With frogs, we have the advantage of the weakest tads dying off if kept communally, and if froglets are kept in groups, we can leave it to them to follow Darwin's "Survival of the Fittest" category. In reality, we're all somehow related, right?


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## Michael Shrom (May 20, 2004)

ISSD Newsletter Volume 1 number 2 March 1988 "Further Observations from the Study of Inbreeding of Dendrobates auratus at the Brookfield Zoo" by Joyce Peterson.

"The objective of our breeding program of Dendrobates auratus has been to raise several generations to observe possible effects of inbreeding. The successive generations reproduction statistics collected through F5 generation do not seem to show any significant trends within the inbred colony towards developmental or survival difficulties when compared with the control group. In some ways the two colonies parallel each other."


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