# Filial Generation Numbers



## Ed (Sep 19, 2004)

One of the things that this (and other herp hobbies) uses in a confusing fashion are the Filial generation numbering system. For some reason, people use this numbering system to denote how many generations a frog or frogs are removed from wild collected animals. While this seems straight forward in actuality it is anything but as I will set an example to demonstrate. 

For example F0 is often used to denote the wild collected adults, while subsequent generations are denoted as 
F1, F2, F3 etc with the number indicating which generation it is removed from the wild. 
So wild caught adults = F0 x F0 produces F1 and F1 x F1 produces F2 etc. 

The problem with this system is that it breaks down as soon as you are not pairing within a generation... 
examples 

F0 x F10, F1 x F3, F5 x F0 and so forth. 

This brings up the question is how do you correctly notate how close they are to the wild caught generation.. obviously F0 x F10 is not going to be as close to the wild caught geneotype (and potentially phenotype) as F0 x F5, or even F1 x F1) and how do you lable it? Should it be F1, F5 (add the two numbers together and divide (this was proposed to me as a method) or F11? The correct answer is F1... 

The reason this breakdown occurs is because the number system is being used in a manner for which it was not designed. A correct usage would be as follows

Parent generation regardless of closeness to wild caught generation is FO (this is because it is a controlled pairing), offspring of those parents are F1, if the F1s are paired together those are F2... If the F1s are paired with something other than thier generation then they are relabled F0 and the offspring are F1. Now some are going are to think that this is confusing and could be interpreted to mean that the frogs are closer to wild type, but is that any less confusing than representing a frog as close to wild type when it is from a F1 x F8 or F4 x F5 versus a F0 x F4 and so forth?

If people want to correctly communicate how many generations a frog or frogs are removed from the wild, then they should simply state that the male had these anscestor(s) (if known) this many generations (again, if known) back that was/were wild caught and repeat the statement for the female. This way people can avoid the confusion of using the F generational number system to attempt to indicate degree of descent from the wild when it wasn't meant to be used in the manner the hobby is attempting to use it...... 

For those interested in reading on how it should be used, a quick google search will pull up multiple references for it. 

Some comments 

Ed


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## hypostatic (Apr 25, 2011)

Let's assume you start off with two unrelated (not WC frogs). You breed them until the F10 generation. With your mounds of frogs, you decide to do a F10xF7 cross. Isn't this technically a backcross? Should you indicate that it is a backcross? Should you still call it F1, or should you give it a more acurately descriptive term like BC1 hybrid? Backcrossing - Wikipedia, the free encyclopedia
Or is this just too confusing to do?


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## Ed (Sep 19, 2004)

Ideally, it should be labled as a back cross (but that doesn't make the identification as F1 from that pairing incorrect).
I was attempting to address the incorrect manner that the hobby was using for designating the number of generations from the wild. 

Even with that labeling, the problem comes in following the genetics down further crosses. 

Some comments 

Ed


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## edwardsatc (Feb 17, 2004)

I find it most helpful when the filial generation is correctly annotated AND parental origin is included (e.g. Stewart x Nabors)


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## Ed (Sep 19, 2004)

edwardsatc said:


> I find it most helpful when the filial generation is correctly annotated AND parental origin is included (e.g. Stewart x Nabors)


I agree. 

Some comments 

Ed


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## oldlady25715 (Nov 17, 2007)

So the higher the filial number the more inbred the frog?


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## Ed (Sep 19, 2004)

oldlady25715 said:


> So the higher the filial number the more inbred the frog?


The only time you can be sure that this is true is if the breeder is using the incorrect usage to designate the number of generations from the wild. 

If you were working with a large diverse group of frogs, you could have a documented multigenerational animals that are not (highly) inbred. This is where some people get caught up with the inaccuracies... The way this is done is that you are documenting the parent frogs so you can backtrack the lineage information to the original animals. This is done by assigning each frog with it's own identification designation and linking the parents to the offspring either on paper or electronically. 

As I noted above, I was simply trying to point out how the hobby was abusing the system and why it was very murky. 

Some comments 

Ed


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