Site-specific frogs: is it possible?

[skylsdale]

No worries, Toby...conversations like these are extremely important for us all to engage in. I hope the thread continues as well...whether it contines discussing captive population management or locale-specific frog collecting, either is very much worth discussing.

[MonarchzMan]

Originally Posted by Toby_H

If the underlined sentence above is true, this is the misunderstanding that allowed the discrepancy…

“Managing allele frequency”, genetic “Snapshot” and genetic “Freeze” indicate keeping the same allele ratio as the wild population. In the quote above you suggest ‘Preserving Genetic Diversity’ not “Frequency”. It does not preserve the allele ratio of the wild stock, but does in fact preserve the diversity.

No, we're maintaining frequency. For example, if we have two phenotypes on the same allele, and in the wild population the phenotypes occur in equal ratios: 50:50. If we let a captive population change get that ratio to 50:1, it still has the same diversity but the frequencies are vastly different from the wild population. And if we were to allow that to happen the captive population would be very different from the wild population. But if we maintained frequencies at 50:50, even if the wild population deviated to 51:49, the captive population would be fairly similar to the wild population. Much more than if we let the captive population get to 50:1.

I don't know where you're getting that snapshot or freeze are not static. Those names inherently mean things do not change. And by that, we mean we do not want to change the frequency of alleles from the wild population at time of collection.

[Toby_H]

Originally Posted by MonarchzMan

I don't know where you're getting that snapshot or freeze are not static. Those names inherently mean things do not change. And by that, we mean we do not want to change the frequency of alleles from the wild population at time of collection.

I did not say that "snapshot" or "freeze" are not static.

On the contrary, I am suggesting that the breeding Guidelines under discussion do not maintain the ratios (or frequency) as you suggest. Please review the following to see how...

Originally Posted by Toby_H

It was suggested I review the Punnet Square Chart and I have…

We are comparing a captive breeding program with a wild population, so we’ll need two charts…

Start both charts with the same breeding population that contains no aa’s and a few Aa’s…

Now on the wild chart, every time an aa is created, erase it. This will reflect the condition being lethal in natural environments thus these individuals do not survive to spawn… but in the captive chart do not erase it, apply it…

You don’t have to go very far to realize that eliminating something makes changes…

This will directly alter the allele ratio…


So in the case that a condition is lethal in wild population but is not lethal in captive environments… please explain how this example is inaccurate.

In post #99 Ed confirmed the above quote would in fact disrupt allele ratios…

Originally Posted by Ed

Only if the ratio of those alleles changes in proportion to the total number of animals in the program. If the population increases proportionally then the increased survivial doesn't matter as the proportion of those alleles remains the same in the population.

In the above quoted scenerio, removing the aa's from the wild population and not removing the aa's in the captive population alters the ratio of big A's to little a's when comparing the two populations...

Please note: when I say "remove the aa's from the wild population" I am not suggesting human culling. This represents a condition being lethal in native condition, which was stated as criteria originally. Not removing the aa's in the captive population represents no human culling which is per the TWI guidelines.

[Ed]

Originally Posted by Toby_H

In the above quoted scenerio, removing the aa's from the wild population and not removing the aa's in the captive population alters the ratio of big A's to little a's when comparing the two populations...

Please note: when I say "remove the aa's from the wild population" I am not suggesting human culling. This represents a condition being lethal in native condition, which was stated as criteria originally. Not removing the aa's in the captive population represents no human culling which is per the TWI guidelines.

I wasn't going to get drawn back into this conversation but given that I am being quoted out of context, I don't have any choice. Toby you are selecting the first portion of the sentence and ignoring the second part of the sentence. The survivial of the homozygote that you purport would be culled in the wild is immaterial in captivity as long as the total allele numbers don't change with respect to the entire population. Increases in the number of homozygote of the non-lethal combination would balance this out. The number of animals carrying each allele is the important factor. It doesn't matter if they are (for a simplistic descripton) AA, Aa, or aa as long as the ratio of A to a in the total captive population is as close as possible to the original frequency. If the frequency of aa or AA or Aa gets too high, then those surplus animals can be deaccessioned from the program to get the correct gene frequency or the numbers of animals carrying the balancing alleles AA, Aa and/or aa can be increased to get the ratio back into balance. One of the reasons it doesn't matter what phenotype is expressed as long as the ratio of alleles in the total population is maintained, is that selective pressures will resolve the issue in the wild. The important thing is that those genes be maintained in the correct frequencies in the total population.

One of the problems with your argument is that you are continually presupposing that the combination of the one (or more) phenotypic expression(s) will always have no survivial value in the wild population or that (as noted in the albino example) it will not have a survivial value as a smaller part of the population. When managing a captive population, we cannot make the assumption that this would be the case as the genes are still present in the population for a reason. If there was that large of a negative survivial value on the phenotype (for the purported alleles) then the population would be eliminating those gene combination(s) and this would be easy to manage as the number of animals in the population with those genes would be very small. This would require only a small number of reproductions to manage as a part of the total population but one has to keep in mind that it is the ratio of those alleles in the total population.

I strongly suggest reviewing the current literature on captive conservation...

Ed

[Toby_H]

This has stopped being fun so long ago… I got so happy when I thought it was over…

Originally Posted by Ed

One of the problems with your argument is that you are continually presupposing that the combination of the one (or more) phenotypic expression(s) will always have no survivial value in the wild population or that (as noted in the albino example) it will not have a survivial value as a smaller part of the population.

You are stating that the criteria of my example is a problem. I admit if you choose to ignore the criteria of my example you will get a different result.

Are you suggesting that there is absolutely no possibility of anything being lethal in wild population and not lethal in captive populations?

A severe allergy to a native plant.

Or are you suggesting that something that is not beneficial is not possible to exist in a wild population. Google “genetic disorder” and to make it even more fun add “list” to that search field.


Had you stated that you are not accepting the criteria of my example a long time ago it would have prevented a lot of this debate.

The Punnet Square example above does prove my point if my criteria is allowed.

[MonarchzMan]

Originally Posted by Toby_H

In the above quoted scenerio, removing the aa's from the wild population and not removing the aa's in the captive population alters the ratio of big A's to little a's when comparing the two populations...

This is not the comparison we're making. The wild population has a ratio of A to a (to emphasize my point, we'll say the ratio is wA:wa to indicate that this is the wild ratio of alleles A and a). We pull a founder population from the wild population, so this captive population has the same ratio of A to a (we'll call this cA:ca).

What we want is wA:wa to EQUAL cA:ca. And in this instance wA:wa ONLY refers to the frequency of alleles of the wild population when we collected the founder stock. We realize that the wild population will change, but in a large enough population (and "large enough" can be a very small number of individuals), these changes are slow. Even in small populations, changes are slow if environmental conditions are constant. The ratio of ratios that you're talking about doesn't make sense.

A ratio is a fraction. We want an equals sign in our equation when comparing captive and wild populations. We only use a division sign (ratio) when we compare allele frequencies WITHIN a population (whether it be the captive population or the wild population).

[Ed]

Originally Posted by Toby_H

You are stating that the criteria of my example is a problem. I admit if you choose to ignore the criteria of my example you will get a different result.

No your understanding of why it doesn’t matter is a problem

Your position has been that maintaining allele frequencies is impossible as frogs with certain phenotypes that would not survive to reproduce in the wild will do so in captivity.

Originally Posted by Toby_H

Are you suggesting that there is absolutely no possibility of anything being lethal in wild population and not lethal in captive populations?

No and that has not been the focus of your argument to my recollection… your position was that phenotypes that would not survive in the wild are allowed to do so in captivity and thus will skew the genetic representation of the population. Are you attempting to change your position?

Originally Posted by Toby_H

Or are you suggesting that something that is not beneficial is not possible to exist in a wild population. Google “genetic disorder” and to make it even more fun add “list” to that search field.

I’m not suggesting that either. As I have repeatedly stated, we cannot know this and as such have to maintain the allele frequency regardless as what is a perceived negative today may be a positive tomorrow.
Contrary to your allusion I have a very strong foundation in genetics between college and what I do for a living…

Originally Posted by Toby_H

The Punnet Square example above does prove my point if my criteria is allowed.

No, actually it doesn’t. It doesn’t matter what portion of the population is AA, Aa or aa as long as the ratio of A to a is the same as when the program was started. A punnet’s square only tells you what the ratio of a given cross would be which is immaterial provided the population is kept at the appropriate ratio of A to a. That is where tracking relatedness and representation in a population resolves this issue.

Ed

[Toby_H]

Originally Posted by Ed

Toby you are selecting the first portion of the sentence and ignoring the second part of the sentence.

This is incorrect. When you accept my criteria, the Punnet example above verifies that the allele ratio is not equal in captive & wild populations after 1 generation and is further out of ratio in each consecutive generation.

When you ignore the criteria of my example and replace it with your own… well you can make it out to do whatever you want it to…

Originally Posted by Ed

The survivial of the homozygote that you purport would be culled in the wild is immaterial in captivity as long as the total allele numbers don't change with respect to the entire population.

But, the total allele numbers do change with respect to the entire population.

If the homozygote (aa) is culled in the wild it directly alters the total allele ratio in respect to the entire population.

This can be verified by running the Punnet Squares I recommended above, provided you do not reject my criteria.

Originally Posted by Ed

Increases in the number of homozygote of the non-lethal combination would balance this out.

It’s not very complicated to understand removing all of the aa’s in the wild population and not removing them in the captive population… will result in less a’s in the wild population (because you removed some!)

Originally Posted by Ed

The number of animals carrying each allele is the important factor. It doesn't matter if they are (for a simplistic descripton) AA, Aa, or aa as long as the ratio of A to a in the total captive population is as close as possible to the original frequency.

but the ratio of A to a in the total captive population is not as close as possible to the original frequency... unless you ignore the criteria of the example...

Originally Posted by Ed

If the frequency of aa or AA or Aa gets too high, then those surplus animals can be deaccessioned from the program to get the correct gene frequency or the numbers of animals carrying the balancing alleles AA, Aa and/or aa can be increased to get the ratio back into balance.

This one really blows me away. You have argued for several pages that the frequency will not change… yet you describe what to do when it does…

What do you do if you cannot “see” the expressed condition (aa). With albinism it’s easy, the frog is white. What if aa is a lung condition? What if it is an allergy? What if it is a deficiency in immunity? What if it is a deficiency to an immunity to something present in the wild environment but not in the captive environment (oh yea, that’s my example!)

I can't believe you just said when the captive population falls out of frequency you simply cull it back into frequency.

Originally Posted by Ed

One of the reasons it doesn't matter what phenotype is expressed as long as the ratio of alleles in the total population is maintained, is that selective pressures will resolve the issue in the wild.

What is "the issue" that selective pressures resolve? Other than an imbalance of allele ratio ijn comparison to the founding stock.


You have all of these "as long as" requirements that your process does not live up to.

Essentially you are arguing that the allele ratio is in balance as long as the allele ratio is in balance...

and you are ignoring the criteria I suggest that puts it out of balance...

[zBrinks]

Watch it, there is no reason for this conversation to not remain civil.

Ed, can you suggest some literature to review on the topic? I have a feeling that may be found helpful.

[Toby_H]

I apologize for my lack of civility… I let frustration get the best of me…


MonarchMan… for some reason it clicked that time. The flaw in my “Punnet Square Comparison” was that I made Punnet Squares for both captive breeding and wild breeding. Instead only the captive population should have been put through a Punnet Square and then compared (per ratio) to the founder stock.

Thank you for helping me see the flaw in my example…


Ed I apologize the frustration that was expressed in my responses to you.


I will make this point one time and will leave it to others to accept or reject…


My previous example was proven inaccurate by displaying that every allele born into the captive population will be needed to sustain allele frequency or the allele ratio.

So if aa is a lethal allele combination… or aa x aa is a lethal cross… Then the loss of these little a’s without a proportionally equal loss of big A’s… the allele ratio in comparison to the founder stock is disrupted…

A real life example I can make:

I breed “Electric Blue Jack Dempseys” (A rare color morph of a common Central American Cichlid/fish). The Blue phenotype (aa) is not lethal… but spawning Blue (aa) with Blue (aa) is a lethal cross.

If the TWI breeding Guidelines were applied to a founding stock of wild Jack Dempseys and a portion of them were Heterogeneous for Blue (Aa), and in that captive population two aa’s were born… and they spawned with one another… which they would eventually have to due to the constant rotation of partners… The aa x aa cross would fail to produce the required aa offspring allowing a deficiency in the “Blue allele” (little a) per the ratio of the founding stock…


I will not debate this new example at length…