# Inbreeding?



## crentania (Jul 22, 2008)

Hi! Newb here. 

I'm getting a few frogs from Patrick in about a week that will be his standard old enough and large enough to ship ~ 4 months old. I know I have about 6ish (probably more) months before I have to worry about anything at all, but I'm a well prepared kinda gal.

Do I need to worry about switching any of them out before they reach breeding age? Has this been known to cause problems or are the lines generally thinned out enough that this won't be an issue? 

I'm worried about getting 4 frogs just adjusted to their new home, and having to switch one or more out for different lines of the same frogs just in case they decide to... erm... "get it on".


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## Julio (Oct 8, 2007)

this is a controversial issue for many people, however there is scientific fact that cold blooded animals can be bred back to theri own blood with no ill effects.


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## herper99 (Mar 21, 2008)

Julio said:


> there is scientific fact that cold blooded animals can be bred back to theri own blood with no ill effects.


What resources did you get this from? I'm not saying that it isn't true. I just don't remember reading any published literature that was so bold as to claim this. :? 

To address your question, you need to understand a bit about genetics. :wink: The reason that inbreeding is dangerous for any species is that it increases the likelihood that offspring will inherit 2 copies of a particular recessive disorder which would otherwise be ineffective if only 1 copy of the allele is inherited. The simple explanation is, all organisms carry some number of recessive alleles (but the types of recessive alleles carried usually vary in unrelated individuals), and when organisms are inbred the chances of inheriting 2 copies of the same recessive allele are greatly increased. 

On a different note, something to keep in mind is that we want to make every effort to increase the genetic diversity of our frogs. We do not want to bottleneck their genetics. Unfortunately, many of the species of pdf's in captivity come from a limited number of genetic lines, so quite a few of the frogs out there are already heavily inbred.


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## crentania (Jul 22, 2008)

Yeah, I think the only reason the question even occurred to me was because of a (limited!) background in genetics. In fact my first assumption for the reasoning behind SLS was probably genetic defects due to inbreeding. But if the diet of the tads changes the chances of SLS, then it's definitely not that .

I'll see if I can find any documented problems stemming from inbreeding and go from there then. If anyone knows a place for some froggy geneology I'll be in heaven.


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## Julio (Oct 8, 2007)

I got this from several journals from the Bronx Zoo's library, also there was an article published by TFH magazine 2-3 years ago regarding the same thing.


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## dneafse (Nov 1, 2006)

Ectothermy/endothermy has absolutely no influence on whether inbreeding will be deleterious for a given species. Herper99's post is right on; deleterious recessive alleles have an increased likelihood of being expressed in a homozygous condition in any diploid species that is bred to close kin. Inbreeding depression is a universal, inescapable consequence of diploid Mendelian inheritance, even if breeders sometimes have limited power to detect reduced fitness due to the cushy, unnatural environment they usually provide for their captives.

There is a somewhat out-of-fashion theory in population genetics that deliberate inbreeding may 'purge' bad recessive alleles (genetic load) by bringing them out of hiding, resulting in the elimination of those bad alleles from the breeding population, and, ultimately, healthier plants or animals. The evidence that this strategy actually works in practice is marginal, however (for a review see http://www.ncbi.nlm.nih.gov/pubmed/12583575).

On average, then, it's safe to assume that an outbred frog will be slightly healthier than an inbred frog, just like a mutt is usually healthier than a purebred dog. That margin of difference in healthiness may not always be large enough to detect under normal captive conditions, but is something to be aware of if one plans to perpetuate a species in captivity over long periods of time. 

-Dan


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## salix (Mar 28, 2008)

I bought six azureus from Patrick and he sent them from four separate sets of parents/lines, each clearly labeled.

Good luck and enjoy your new frogs.


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## crentania (Jul 22, 2008)

Exactly what I was trying to get at Dan. Of course, I don't have the grammar at my disposal that you seem to . Thank you!

And yes, Deb, I'm hoping that'll be the case and I won't have to worry about it. But I'm not sure how many lines are actually available for P. Vittatus, and if he has more than one available to him. 

The frogs are shipping tomorrow, so I'll have them by Thursday. Here's hoping he has separate lines for his Vittatus!


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## Frogstang29 (Oct 29, 2007)

If we are going to compare a simple organism like frogs to more complex organisms such as ourselves, than we are just arguing for the sake of arguing. If you knew anything about genetics you would know that as we go up the evolutionary ladder and organisms become more complex there is a much larger margin for error. I'm not saying inbreeding is good for anything in the long run but to go off on people because you want to flex your muscles on a web forum by throwing around terminology most wouldn't be familiar with in order to appear more right is (staying in the spirit of this thread) retarded. The fact is that the simpler the organism the less of an effect inbreeding has on it. To say that our captives are kept in a cushy environment like that's something bad is ridiculous. Look around you, do we not live in a cushy environment compared to our ancestors? I doubt most of us could function if left to our own hunter and gathering devices sans our modern luxuries. We've effectively halted our own evolution through medical treatments for almost anything that ails us where as in the past our inferior genes would just die out eliminating them from the pool, further strengthening our line. So when you get that uppity about inbreeding in frogs, I say there are far worse things to do to your frogs than inbreeding and I wouldn't worry too much about it unless your group expresses some bad chromosomes. It should be evident fairly early and you can cull accordingly. Unless of course you want to live everyday in fear that your frogs are getting it on with their siblings, I mean what would the neighbors think. My god.


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## markbudde (Jan 4, 2008)

Ah, at this point the thread can rapidly devolve so I will try and stay civil and I hope everyone else does as well.



Frogstang29 said:


> If we are going to compare a simple organism like frogs to more complex organisms such as ourselves, than we are just arguing for the sake of arguing.


I don't know on what basis one can say that a frog is less complex than a human.



Frogstang29 said:


> If you knew anything about genetics you would know that as we go up the evolutionary ladder and organisms become more complex there is a much larger margin for error.


This is an unnecessary person attack. And it's not clear by what metric you mean things are more complex as you "go up the evolutionary ladder".




Frogstang29 said:


> The fact is that the simpler the organism the less of an effect inbreeding has on it.


Again, any citations?



Frogstang29 said:


> So when you get that uppity about inbreeding in frogs, I say there are far worse things to do to your frogs than inbreeding and I wouldn't worry too much about it unless your group expresses some bad chromosomes. It should be evident fairly early and you can cull accordingly.


The problems won't necessarily manifest early on. Many genetic problems don't manifest until later in life or cause sterility issues at maturity.

To answer the initial question in this thread: many lines in captivity have been inbred to the point where deleterious genes have already been removed from the population. It's better to not cross siblings, but if you can't avoid it don't stress too much. I have two siblings together and wish (in retrospect) that I have spent more time getting unrelated frogs.

Good Luck,
Mark


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## Frogstang29 (Oct 29, 2007)

Gonna go out on a limb here. I didn't address individual issues that could arise from inbreeding, but I felt that sterility was a nonissue since, well, that problem solves itself.


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## markbudde (Jan 4, 2008)

If someone bought inbred offspring only to find out that they never got fertile eggs, they may consider sterility a very serious issue.


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## Frogstang29 (Oct 29, 2007)

It may be serious as a disgruntled customer looking to buy a breedable pair issue but in the genetics world it serves to eliminate that frog from spreading it's inferior genes. Nature has it's way of maintaining balance and sterility is one of those checks and balances. Sterility is an anomaly not hereditary. You can't inherit your parents sterility.......


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## markbudde (Jan 4, 2008)

I think maybe we are discussion separate issues. In the evolutionary sense, occasional inbreeding is not a big problem. But in the short term, which we live in, there can be serious consequences of inbreeding, one of which is sterility of the offspring. I don't mean to dwell on sterility, as this is only one potential issue, but it is a common and serious one. I think the customer would be right to be disgruntled, if after all the work the did to get their frogs happy, it turned out that the frogs were sterile due to poor planning of the seller. And it is entirely possible to inherit sterility through inbreeding. For instance...

If there is a large population of frogs, and a rare recessive mutation which causes a sperm defect, very few frogs would ever be effected by it because the chance of getting 2 bad copies of the genes from two unrelated parents is very small. But it is likely that two offspring of a the same parent would carry the mutation. When these two offspring are inbred, 1/4 of their male babies will turn out sterile, which would be very frustrating for whoever ends up with them. It could take a very long time and a lot of wasted energy to determine the reason why their pair of frog won't lay fertile eggs.

Even more confusingly, the gene, in a single copy, may not be bad. In fact, in a single copy, it may allow the frog to make more sperm than normal. So, by inbreeding, you may be losing a potentially valuable gene.


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## dneafse (Nov 1, 2006)

Frogstang29 said:


> If you knew anything about genetics you would know that as we go up the evolutionary ladder and organisms become more complex there is a much larger margin for error.


Frogstang29, I'm a population geneticist by trade, and was trying to help out by dispelling an old misconception (which you restated above). 



Frogstang29 said:


> I'm not saying inbreeding is good for anything in the long run but to go off on people because you want to flex your muscles on a web forum by throwing around terminology most wouldn't be familiar with in order to appear more right is (staying in the spirit of this thread) retarded.


I didn't use any terminology that isn't covered in a basic intro bio course, and was not trying to be uppity. Sorry if I came off that way. I think most folks who read this subforum are into breeding and are familiar with terms like 'homozygous', 'recessive,' and 'diploid.' If that terminology is unfamiliar or too high-falootin' for anyone, wikipedia has a great entry on genetics and Mendelian inheritance:

http://en.wikipedia.org/wiki/Genetics



Frogstang29 said:


> So when you get that uppity about inbreeding in frogs, I say there are far worse things to do to your frogs than inbreeding


I agree that there are far worse things you could do to your frogs. I thought that saying that inbred frogs 'on average' would be slightly less fit than outbred frogs, and that the margin of difference would often be too small to be detectable in captivity, was a reasonable, non-absolute way to frame the issue. 

I'm not going to bother rebutting any of the other misinformation you've re-introduced into this thread, and this will be my last post on this topic. Thanks!

Dan


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