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Old 01-20-2017, 04:43 AM
Ed Ed is offline
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Default Re: The Importance of Letting Frogs be Frogs?

Quote:
Originally Posted by TarantulaGuy View Post
True, natural selection is not the best phrase to utilize here, it was pretty late last night. I hesitate to call it artificial selection either at that point, as I think one is more artificial than the other.
In that case, perhaps the term you are looking for is relaxed artificial selection as it by definition isn't as directed as artificial selection implies.


Quote:
Originally Posted by TarantulaGuy View Post
Indeed. But, given that none of our populations are ever going to be introduced back into the wild, I think striving to make them as well adapted to captive life as possible isn't necessarily a bad thing.
It can if it results in the loss of genetic diversity to withstand parasites or diseases. There have been more than a few examples of how the loss of genetic diversity in domestic populations can result in bad outcomes for the captive populations. On the global scale consider the Irish Potato famine or how the loss of thermregulatory ability puts this captive population of feathertail gliders at risk. Geiser, F., and C. Ferguson. "Intraspecific differences in behaviour and physiology: effects of captive breeding on patterns of torpor in feathertail gliders." Journal of Comparative Physiology B 171.7 (2001): 569-576. free access at https://www.une.edu.au/__data/assets...batesJCP01.pdf

That feathertail glider population could go extinct with one power outage ... and as a hobby we'd be remiss in assuming that something like that could happen hence the argument for greater genetic diversity versus domestication should always be made.


Quote:
Originally Posted by TarantulaGuy View Post
I'm not sure being adapted to captivity necessarily leads to them not breeding; but animals that are predisposed to not breed because of genetic factors are certainly not going to be favored in the population because of obvious reasons.
Hmm, are you so sure about that? Consider Old English Bulldogs, domestic chickens that do not incubate their eggs, double breasted turkeys ...

Quote:
Originally Posted by TarantulaGuy View Post
I guess my argument is that in the lesser of two evils, it's preferable to wean out tadpoles that even in a vivarium setting would not be able to hatch normally and then undergo the transport process.
Hatching normally is different than pulling eggs for outside rearing. For successful hatching the tadpole has to be able to secrete an enzyme to digest the membranes of the eggs so it can successfully escape. Cutting tadpoles out of the eggs should be discouraged unless there are extreme extenuating circumstances.

Quote:
Originally Posted by TarantulaGuy View Post
My main point though is that in our given populations coddling every egg mass through to hatching instead of letting the parents do it is not necessarily beneficial.
I can agree that it isn't necessary but the glut of animals in the hobby and the prices that they are sold for is an artificially created issue due to the whole not selling to a reseller or wholeseller dogma and that issue should also be addressed here are it is part of the whole equation.

One of the biggest drivers of the whole attempt to rear every egg mentality is that people who produce a lot of eggs are able to acquire greater status in the hobby despite the fact that pretty much all of the difficulty in breeding these frogs has been eliminated and if a person can follow a recipe they can have success ...

Quote:
Originally Posted by TarantulaGuy View Post
I think that the thermal differences we are talking about here are negligible in the scales we're dealing with. I've browsed around a few papers and haven't really seen good evidence that a half degree F difference will have a statistically significant effect on developmental rates.
However you can have more than a 0.5 F variation within a couple of inches if one area gets a greater proportion of direct sunlight. The difference between direct sun exposure and shade could be 10-15 degrees difference depending on air movement and humidity.


Quote:
Originally Posted by TarantulaGuy View Post
agree though that there certainly variables, even in our relatively closed systems, that could effect clutch development, but I'm not yet (show me the data!) convinced that those variables play a bigger or more important part then the over-riding fitness of the eggs.
The problem is eliminating environmental conditions as the causal difference as opposed to negative genetic tendencies. Selecting only the early hatchers or the later hatchers as not having negative (or less negative) genetic tendencies is a problem as you don't know what your actually selecting for; see the feather tail glider reference above as an example of this.. or consider that the variation could be due to phenotypic plasticity as seen in translocated pupfish...

Quote:
Originally Posted by TarantulaGuy View Post
I'm of the opinion that larvae that wouldn't normally survive a hatching process are probably not going to be the ones with uber-strong immune responses, at least in most situations. And does the benefit of getting that rare frog with some immune response superior to the population at large outweigh the what is more likely effect of introducing the countless other weaker frogs that wouldn't normally have survived a hatching process, other than for our coddling of them?
Consider that many of the activities such as tadpole tea or methylene blue to ensure that tadpoles hatched were in part as a result on insufficient vitamin A reserves in the adults when the eggs were provisioned. How much genetic damage could have been done to a population if only those tadpoles that hatched without the adjuncts were allowed to breed? The problem again is being able to determine those problems that are the result of genetic faults as opposed to those that originate in husbandry or environmental factors.



Quote:
Originally Posted by TarantulaGuy View Post
That being said, I frequently see on these boards methylene blue being recommended as a treatment to hatch eggs that consistently mold; which I view as skirting the actual problem. Doing it that way, you're allowing eggs and individuals that really had no business surviving to get into the hobby and pass on those poor traits.
See above, I suspect that many of these cases are due to one or more husbandry issues as the recommendation is often that the frogs will get it right eventually ... On the otherside, welcome to the world of fighting against dogma...


Quote:
Originally Posted by TarantulaGuy View Post
You could, but how many people are actually willing to do this? Convincing people that eliminating the hybrid threat and market swamping are more important issues than making 10$ per frog instead of 35$ is difficult. I'm not convinced we can do it.
This is one of the areas where consistent repetition is important ... if it isn't consistently presented then it will never change ... which is why I've said it more than a few times ....

Quote:
Originally Posted by TarantulaGuy View Post
But generally, our populations are far larger than what the minimum number required for a decent genetic diversity requires. Not always, but mostly.
If you consider popularity swings, do you think this is still true??


Quote:
Originally Posted by TarantulaGuy View Post
And unfortunately, the data sets we really need to talk about most of the above issues just don't exist when it comes to long term captive husbandry of amphibians. So, unless presented with the data (which I'd love to see if it exists), I'm left with going with my gut feelings on how to manage the frogs I work with.
So wouldn't a more conservative approach be the warranted that is likely to sustain maximal genetic diversity as opposed to only allowing tadpoles that were transported to survive? Hatching on their own is one thing.....

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Ed
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Last edited by Ed; 01-20-2017 at 04:46 AM.
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